Information

Are there nerves in the umbilical cord?


I have always imagined that cutting the umbilical cord after birth might be painful. But I have always been confused about who would feel the pain and why. It occurred to me that the mother or the infant could only feel pain if they had nerves connected to the umbilical cord.

  1. Do either mother or infant have nerves running into the umbilical cord that carry nociceptive information?
  2. If not, is there a reason why no pain receptors are present?

Short answer
There are no functional nociceptors present in the umbilical cord.

Background
Having had the opportunity to cut the umbilical cord of one of my kids, I can anecdotally confirm neither newborn nor mother gave any sign of pain during the procedure. That is, when cutting the umbilical after the birth of a full-term baby. The only person clenching his teeth was dad :)

In fetuses at gestational age of 18-36 weeks no stress response was noted after puncturing the umbilical (Teixeira et al., 1996), indicative of the absence of pain receptors connected to the baby's brain.

I couldn't find information about pain in the mother, but I cannot imagine that the maternal central pain centers are being connected to the umbilical, which would be pretty extraordinary. This, because long-distance neural connections are rarely, if ever, established in adult humans. Also, I haven't heard any reference to the mother feeling pain because of injury to the umbilical cord. For example, knots in the umbilical cord, or cords wrapped around the fetus' neck due to excessive movements of the fetus are never noticed by the mother, and are only revealed during ultrasounds.

Note, however, that the umbilical cord is innervated by cholinergic neurons that are thought to be involved in the control of blood transfusion to the fetus, but presumably do not carry sensory information to either fetus or mother (Ellison, 1971).

References
- Ellison, Am J Anat (1971); 132: 53-60
- Teixeira et al., The Lancet (1996), 347: 624


Yes there are

THE placenta and foetal membranes are usually described as being devoid of neural elements1,2. In other descriptions, the possibility of an innervation is not considered3,4. Nevertheless, reports of the presence of nerve elements in these foetal tissues continue to appear in the European literature5-7.

https://www.nature.com/articles/214103a0

They are especially small


Umbilical Cord- Structure, Functions, Storage, Abnormalities & Infections

The umbilical cord is a tube-like structure that starts to form during the 5th week after conception, connecting the developing fetus to the placenta. It is also called a ‘supply line.’ It transports nutrients and oxygen to the fetus and carries out the removal of fetal waste products.


ICSE Biology Question Paper 2007 Solved for Class 10

ICSE Paper 2007 BIOLOGY
SECTION-I (40 Marks)

(Attempt all questions from this Section)

Question 1:
(a) Name the following:
(i) Cytoplasmic organelles that help in the manufacture of starch.
(ii) The statistical study of human population.
(iii) Pair of genes responsible for a particular characteristic in an individual.
(iv) A solution whose concentration is greater than that of the cell sap.
(v) The fluid that provides protection and nourishment to the cells of the brain. [5]

(b) State whether the following statements are true or false. If false, write the correct statement by changing the incorrect word / words only.
(i) Mortality is the number of deaths per thousand of the population per decade.
(ii) The symbiotic bacteria that helps in Nitrogen fixation is Rhizobium radicicola.
(iii) Rods are responsible for vision in the dark.
(iv) The dark reaction of photosynthesis is light independent.
(v) Process of fusion of the sperm nucleus and the egg nucleus is termed implantation. [5]

(c) Match the items in column A with those which are most appropriate in column B. You must rewrite the matching pairs :

Column A Column B
1. Basic unit of life A. Glucagon
2. Beta cells of Pancreas B. Meninges
3. Meiosis C. Iris
4. Protective covering of the brain D. Cell
5. Constriction of the pupil of the eye E. Insulin
F. Skin cell
G. Protoplasm
H. Sperm
I. Ciliary muscles

(d) Given below is an apparatus used to study a particular process in plants. Study the same and answer the questions that follow:
(i) Name the apparatus.
(ii) Mention one limitation of this apparatus.
(iii) Which phenomenon is studied with the help of this apparatus ?
(iv) What is the function of the part marked ‘reservoir’ ?
(v) What is the role of the air bubble in the experiment ? [5]

(e) In the box given below a list of biological terms that can be used to complete statements that follow. Select the appropriate term from the box and re-write the completed statement. You may use a term only once.
Concave, Neuron, Lactic acid, Glucose, Animal waste, Gestation, Nerve, Ethyl alcohol, Nephron, Myopia, DDT, Pregnancy, Convex.
(i) The type of lens uqpd to correct myopia is ……… .
(ii) The basic unit of the human brain is the ……… .
(iii) The end product of fermentation is ……….. .
(iv) A non-degradable pollutant is ……….. .
(v) The period of complete development of the foetus till birth is termed ………. . [5]

(f) Given below are the functions of certain organs I structures found in living organisms. In each case, name the organ or structure that:
(i) Produces testosterone.
(ii) Is responsible for protecting the eye from sweat.
(iii) Transmits characteristics from parent to offspring.
(iv) Transports water from the soil to other parts of the plant.
(v) Initiates cell division. [5]

(g) Explain the following terms:
(i) Tropic hormone
(ii) Guttation
(iii) Osmosis
(iv) Stereoscopic vision
(v) Mutation. [5]

(h) Given below is a set of terms arranged in logical sequence, representing a process or a function. Of these, one term is incorrect. Identify the incorrect term and replace it with the correct term. One has been done for you as an example.
Eg. Pollen grain —> Exine —> Staminal tube —> Male gametes —> Micropyle
Incorrect term — Staminal tube
Correct term — Pollen Tube
(i) Seminiferous tubule —> Sperm —> Sperm duct —> Accessory glands —> Semen —> Ureter.
(ii) Soil water —> Root hair —> Cells of cortex —>Epidermis —> Xylem.
(iii) Oxygen —> Stoma —> Respiratory cavity —> Mesophyll cells —> Oxidation of glucose —> A.T.P
(iv) Pupil —> Eye lens —> Vitreous humour —> Fovea —> Auditory nerve.
(v) Sensory nerve —> Dorsal root ganglion —> Sensory Neuron —> Motor neuron —> Receptor. [5]

Answer:
(a) (i) Chloroplast
(ii) Demography
(iii) Allele
(iv) Hypertonic
(v) Cerebrospinal Fluid

(b) (i) False. Mortality is the number of deaths per thousand of the population per year.
(ii) True.
(iii) True.
(iv) True.
(v) False. Process of fusion of the sperm nucleus and the egg nucleus is termed fertilization.

Column A Column B
1. Basic unit of life D. Cell
2. Beta cells of Pancreas E. Insulin
3. Meiosis H. Sperm
4. Protective covering of the brain B. Meninges
5. Constriction of the pupil of the eye C. Iris

(d) (i) Ganong’s Potometer.
(ii) Any changes in the outside air temperature may affect the position of the air bubble in the capillary tube.
(iii) Transpiration.
(iv) Reservoir helps in bringing back the bubble to its original position. This can be done by releasing some water into the capillary tube by opening the stop-cock.
(v) The rate of water uptake can be calculated by timing the movement of air bubble over a fixed distance on the scale.

(e) (i) The type of lens used to correct myopia is Concave.
(ii) The basic unit of the human brain is the Neuron.
(iii) The end product of fermentation is Lactic acid.
(iv) A non-degradable pollutant is Animal Waste.
(v) The period of complete development of the foetus till birth is termed Gestation.

(f) (i) Interstitial cells of testes.
(ii) Eyebrows.
(iii) Genes.
(iv) Xylem.
(v) Centrosome.

(g) (i) Tropic Hormone: It refers to that hormones which stimulate other endocrine glands to produce their specific hormones.
(ii) Guttation: The process by which intact plant loses water in the form of droplets through pores (hydathodes) is called as guttation.
(iii) Osmosis: Osmosis is the diffusion of water molecules through a semi- permeable membrane from a dilute to concentrated solution.
(iv) Stereoscopic vision: When both the eyes are focussed on the same object but from different angles, it is called binocular or stereoscopic vision. All the monkeys, apes and particularly man have binocular vision.
(v) Mutation: Sudden changes in one or more genes or in the number and structure of chromosomes in the progeny, which normally may not have existed in^he parents, grand parents or even great grand parents.
Example: Albinism.

(h) (i) Incorrect term: Ureter.
Correct term: Penis.
(ii) Incorrect term: Epidermis.
Correct term: Optic Nerve.
(iv) Incorrect term: Auditary Nerve.
Correct term: Endodermis.
(v) Incorrect term: Receptors.
Correct term: Effectors.

(Attempt any four questions from this Section)

Question 2:
(a) Differentiate between the following on the basis of what is given in brackets :
(i) Bio-fertilizer and chemical fertilizer (an example of each).
(ii) Karyokinesis and Cytokinesis (Explain the terms).
(iii) WHO and Red Cross (Any one function of each).
(iv) Mitosis and Meiosis (Number of daughter cells formed).
(v) Pure and Hybrid strains (Definition). [6]

(b) Given below is the diagram of the human ear. Study the same and answer the questions that follow :
(i) Give the biological term for the part labelled ‘A’ and state its function.
(ii) Name the part labelled ‘B’ and state its function.
(iii) Name the part labelled ‘C’ and state its function.
(iv) Give the function of ear wax. [4]

Answer:
(a)

(b) (i) Part labelled ‘A’ is called as ear ossicles. It is made up of three bones malleus, incus and stapes. These ear ossicles transmit the sound waves from external to the internal ear.
(ii) Part labelled ‘B’ is called as eustachian tube. It acts as ventilator to equalize pressure of air on both the sides of tympanic membrane that forms the outer boundary of middle ear.
(iii) Part labelled ‘C’ is auditory nerve (vestibular and cochlear nerve) which carries hearing impulses to the brain.
(iv) Ear wax lubricates the tympanum for proper functioning.

Question 3:
(a) Answer the following questions briefly:
(i) Why is carbon dioxide considered an air pollutant ?
(ii) Name any two vaccines and mention the diseases against which they give immunity.
(iii) Mention two reasons for the high birth rate in India.
(iv) State two effects of the smog observed, in major cities. [5]

(b) Given below is an experiment, set up by a candidate, to study the process of respiration in plants. The candidate failed to get the expected results, as two mistakes were made while setting up the experiment:
(i) Identify and state two mistakes made by the candidate.
(ii) What is th&role of soda lime in the experiment ?
(iii) What is the purpose of using lime water in flask ‘A’ and ‘B’ ?
(iv) Give the chemical equation to represent the process of respiration. [5]

Answer:
(a) (i) Carbon dioxide is considered as an air pollutant. Because it mixses with oxygen present in air and forms carbon monoxide which is harmful to man, vegetation, animals or even buildings.
(ii) BCG vaccine is given against tuberculosis.
DPT vaccine is given against the diseases viz Diptheria, Pertussis and Tetanus.
(iii) 1. Illiteracy
2. Desire for a male child.

Question 4:
(a) (i) Draw a neat and well-labelled diagram of the chloroplast.
(ii) List the events taking place in the photo-chemical phase of photo-synthesis.
(iii) If you are planning an experiment to shew the effect of light on photosynthesis:
(1) Will you select white light or green light ? Justify your answer.
(2) Why would you select a destarched plant ? [5]

(b) (i) Explain the term reflex action.
(ii) Expand the following biological abbreviations:
(1) DNA (2) AIDS.
(iii) State whether the following actions are ‘voluntary action, simple reflex or conditioned reflex’:
(1) Blinking
(2) Cleaning the table
(3) Playing on the keyboard
(4) Salivating when food is put in the mouth. [5]

Answer:
(a) (i)

(ii) Following events take place in the photo-chemical phase of photo¬synthesis :
(1) Activation of chlorophyll.
(2) Splitting of water (Photolysis).

(3) The hydrogen ions are picked up by a compound NADP to form NADPH.

(4) The oxygen component is given out as molecular oxygen.
2O ——> O2
(5) The electrons are used in converting ADP into energy rich compound ATP by adding one phosphate group P2.

(iii) (1) We will select white light because it will absorb green light and reflects other colours.
(2) We will select a destarched plant because destarching ensures that any starch present after the experiment has been formed under experimental conditions.
(b) (i) Reflex Action: Reflex action is an automatic, quick and involuntary action in the body brought about by a stimulus.
Reflexes are of two types : (1) Simple (natural) reflexes and (2) Conditioned (acquired) reflexes.
(ii) (1) DNA: Deoxyribose Nucleic Acid.
(2) AIDS: Acquired Immune Deficiency Syndrome.
(iii) (1) Blinking: Simple Reflex.
(2) Cleaning of table: Voluntary Action.
(3) Playing on Keyboard: Conditioned Reflex.
(4) Salivation when food is put in: Conditioned Reflex.

Question 5:
(a) Given below is a diagrammatic representation of a defect of the human eye :
(i) Identify-the defect.
(ii) Mention two reasons for the above defect.
(iii) State how the defect can be rectified.
(iv) Name the part of the eye responsible for maintaining the shape of the eyeball. [5]

(b) Name the hormones which lead to the following conditions :
(i) Diabetes Mellitus Exophthalmic goitre.
(ii) Growth of beard in women
(iii) Myxedema
(iv) Gigantism [5]

Answer: (a) (i) “Hypermetropia” because the image is formed behind the retina.
(ii) Two reasons:
1. Shortening of the eyeball from front to back.
2. The lens is too flat.
(iii) The defect can be rectified by the use of convex (converging) lens.
(iii) Ciliary muscles control/maintain the shape of the eye ball.

(b) (i) Insulin.
(ii) Sex corticoids.
(iii) Thyroxin.
(iv) Somatotropin.
(v) Thyroxin.

Question 6:
(a) Study the diagram given below and then answer the questions that follow :
(i) Name the parts labelled 1 and 2. State the function of each part.
(ii) State any one function of the amniotic fluid.
(iii) What’ is the role of the umbilical cord in the development of the foetus ?
(iv) Name the part in the diagram which is endocrine in nature. [5]

(b) (i) State Mendel’s law of Independent Assortment.
(ii) A homozygous Tall plant (T) bearing red coloured (R) flowers Amniotic Fluid is crossed with a homozygous Dwarf plant (t) bearing white flowers (r):
(1) Give the Genotype and Phenotype of the F1 generation.
(2) Give the possible combinations of the gametes that can be obtained from the F1 hybrid.
(3) Give the dihybrid ratio and the phenotype of the offsprings of the F2 generation when two plants of the F1 generation above are crossed. [5]

Answer:
(a) (i) Part labelled 1: Placenta: It helps in the nutrition, excretion and respiration of the embryo.
Part labelled 2: Chorion: It forms the placenta.
(ii) Amniotic fluid acts as a cushion for the embryo and protect it from jerks or mechanical shocks.
(iii) Umbilical cord contains blood vessels and connects the placenta with the foetus. It means it helps in providing nutrition to the embryo and O2 to foetus and removes CO2 and excretory wastes from foetus blood to maternal blood.
(iv) Endocrine part of this diagram is ‘placenta’.

(b) (i) Mendel’s law of Independent Assortment: When there are two pairs of contrasting characters, the distribution of the members of one pair into the gametes is independent of the distribution of the other pair.
(ii) (1) Genotype of the F1 generation – TtRr,
Phenotype of the F1 generation – Tall plant and Red flower.
(2) Possible combination of the gametes from F1 hybrid: TR, Tr, tR, tr.
(3) Dihybrid ratio and phenotype of the F2 generation:

Question 7:
(a) The diagram given below represents a stage during mitotic cell divisions in an animal cell:
(i) Identify the stage. Give a reason to support your answer.
(ii) Name the parts labelled 1, 2 and 3.
(iii) What is the chromosome number of the cell ?
(iv) Draw a neat, labelled diagram of the cell as it would appear in the next stage. Name the stage. [5]

(b) Give reasons for the following:
(i) Plants begin to die when excess of soluble fertilizers are added to the soil.
(ii) Injury to the medulla oblongata results in death.
(iii) Gametes have a haploid number of chromosomes.
(iv) Green leaves are thin and broad.
(v) Lysosomes are termed suicidal bags of a cell. [5]

Answer:
(a) (i) This diagram represents ‘anaphase’ of the mitosis division. In this centromere is divided separating sister chromatids of each chromosome. They are now drawn apart towards opposite poles.
(ii) Parts labelled 1 —> aster rays.
Parts labelled 2 —> spindle fibres.
Parts labelled 3 —> chromatids.
(iii) 4 Chromosomes. Just double of the parent cell.
(iv) Stage: Telophase.

(b) (i) Because of plasmolysis of plant cells due to hypertonic solutions of fertilizers.
(ii) Because due to injury in medulla oblongata, the projecting process of the axis vertebra in the neck pierces it. As a result the involuntary actions such as breathing and heart beat are stopped.
(iii) Because gametes undergo meiosis (reduction) cell division in which the number of chromosomes becomes half.
(iv) Green leaves are thin and broad so that more surface area is exposed to sunlight for photosynthesis.


Makeup and composition

The umbilical cord is made of Wharton's jelly, not ordinary skin and connective tissue. There are no nerves, so cutting it is not painful, but it is very strong, like thick sinew, and requires a sharp instrument if it is to be cut. Provided that umbilical severance occurs after the cord has stopped pulsing (5-20 minutes after birth), there is ordinarily no significant loss of either infant or maternal blood while cutting the cord. The cord contains one vein, which carries oxygenated blood (from the mother to the fetus) and two arteries that carry deoxygenated blood (from the fetus back to the mother).

Cord blood

Provided that the cord is not clamped for the first 5 minutes after birth, and kept level with the newborn, it allows baby to receive many maternal antibodies, critical stem cells, hormones, and vitamin K and provides the neonate with one-third to one-half of its entire blood volume.

Loss of this volume of blood through harvesting for blood banking can be the equivalent of subjecting an infant to a massive hemorrhage. This cord blood is a rich source of primitive, undifferentiated stem cells (i.e. CD34-positive and CD38-negative) which assist in neonatal adaptation. A cord blood bank is in the business of cord blood harvesting, and is NASDAQ listed. These companies promote very early cord clamping and cutting, to freeze for long-term cryo-storage at a cord blood bank should the child ever require the cord blood stem cells for rare diseases (for example, to replace bone marrow destroyed when treating leukemia). This practice is controversial: the RCOG (Royal College of Obstetricians and Gynaecologists, Great Britain) in its 2006 opinion states, "There is still insufficient evidence to recommend directed commercial cord blood collection and stem-cell storage in low-risk families." Child health advocates criticize the aggressive marketing campaigns of blood banks to pregnant parents-to-be as misleading, and assert that early cord blood withdrawal may actually increase the likelihood of childhood disease.

For-profit cord blood banks receive from 80 ml to 180 ml of blood on the average amount of blood taken for CBC (cord blood collection). 'Banking' cord blood involves immediate, very early cord clamping to take a significant amount of blood (100mL on average) from the newborn at a crucial neonatal time. The amount of blood taken from the newborn child by early cord clamping can be understood by the fact that a 9 pound baby only creates 10 ounces of blood (300 ml). Therefore 180 ml is actually more than half this baby's blood supply and taking half of one's blood supply will weaken any child, or any adult that loses blood.

The cord banking business markets the use of CBEs as a mechanism that would eliminate the ethical difficulties associated with embryonic stem cells, however cord blood harvesting itself is fraught with ethical difficulties. (ESCs). [6]

The American Academy of Pediatrics 2007 Policy Statement on Cord Blood Banking title states that:

"Physicians should be aware of the unsubstantiated claims of private cord blood banks made to future parents that promise to insure infants or family members against serious illnesses in the future by use of the stem cells contained in cord blood"

"Cord blood collection should not be performed in complicated deliveries. The cord blood stem cell–collection program should not alter routine practice for the timing of umbilical cord clamping" and

"Private storage of cord blood as "biological insurance" should be discouraged, and that cord blood banks should comply with national accreditation standards developed by the Foundation for the Accreditation of Cellular Therapy (FACT), the US Food and Drug Administration (FDA), the Federal Trade Commission, and similar state agencies."


The Umbilical Cord Stump

While in college, I tutored the following subjects for two years: Anatomy & Physiology, Biology (general and Advanced), and Microbiology. Yet there is one area I was never made privy to: the timeline of the umbilical cord. Going into the last weeks of childbirthing class with my wife, I suddenly find it psychologically incommoding I never learned that following labor and delivery, the umbilical cord is not cut all the way down to the bellybutton.

Yes, all the way down to the bellybutton.

Maybe you’re like me and didn’t know this.

Suddenly, I feel like the dumbest person on Planet Earth for not knowing this.

For the last 36 weeks, I have been a bit scared of having the honor of cutting my baby’s umbilical cord.

“Who needs scissors,” I told my wife when she was around 24 weeks. “I’m using my teeth. Look at these incisors.”

Then I grabbed the air with two hands as if I was holding an invisible rope and started gnawing.

Humor comforts me in times of the unknown.

Note to future dads: Your wife probably won’t find this amusing.

What if I didn’t cut far enough and my baby had an outie? I remember back in the summer days of my youth thinking that kids at the pool with outies looked funny.

Or what if I cut too close and my baby has the ultimate innie, a three-inch deep crater that will collect lint for all eternity? All this time, I’ve been terrified I would cut the umbilical cord much too close to my baby’s stomach and cause some nightmarish infection, thus subjecting my first born to weeks of antibiotic treatment and various hypoallergenic ointments 3x a day.

All because I cut the umbilical cord too close to the bellybutton.

And it would be all because of me.

The man she would grow up idolizing and compare all men to who ultimately could never measure up .

Or at least this is what I like to tell myself.

Then I learn the real story: that after I cut the cord—not all of it, just some of it—a clamp is placed on the leftover upright noodle and remains clamped until a week or so later when said umbilical cord dries up and falls off.

“If you’re lucky,” our childbirth instructor said, “You’ll go to pick up your baby after a nice, long rest and you’ll see the umbilical cord lying there in the crib.”

Like a fat earthworm that has baked in the hot sun?

Shouldn’t someone have sent out a mass e-mail to all expecting parents that along with taking your baby home, you also take home part of the umbilical cord?

Look, I’m not grossed out by this.

But why is it I didn’t know this?

When I told my mom that Allison and I were expecting she didn’t tell me about the umbilical cord.

Neither did those Biology textbooks.

Then again, we never did get to the very end.

Science is sort of like history in that regard. You never get to the Civil Rights Movement or Vietnam, nor do you get to the nitty-gritty in concern to the timeline of the umbilical cord.

Whereas I’m the youngest of two children, my wife is the oldest of four. She knew this already. Maybe all women do. Maybe this tidbit of information is something all women receive when they get their ears pierced.

Allison’s youngest sibling is nine years younger than her.

“I remember when I was a kid, Emily [her sister] and I would go into the nursery each morning to see if Carrington’s umbilical cord had fallen off yet,” she said to me while we were eating some 80/20 Angus Beef hamburgers I’d cooked up.

“What do you mean you’d go in and see if the umbilical cord had fallen off?”

“What do you mean by ‘it dries up’?”

“It dries up and falls off.”

“What did you think happened to it?”

“It stayed at the hospital . . . with the placenta.”

So let this be a lesson to all you expecting first-time fathers out there. When you go in the nursery to snatch up your baby for a good rocking and see what appears to be either a turd or a chewed up cigar in the crib, Red Auerbach has not returned from the dead and been watching over your baby at night. That’s your baby’s dried up umbilical cord stump.

And let this also be a lesson that I am apparently not the right man to talk to in regard to tutoring you for any Biology class, especially Anatomy & Physiology.

As for me, I guess it’s about time I get some shuteye. As the story goes, there isn’t much of that in my near future. But it’s all gravy.


The nervous system exerts rapid control by serving three broad functions: sensory, integrative, and motor.

  • First, it senses changes within the body and in the outside environment this is its sensory function.
  • Second, it interprets the changes this is its integrative function.
  • Third, it responds to the interpretation by initiating action, such as muscular contractions or glandular secretions, this is its motor function.

Functional organization of the nervous system

The nervous system is composed of two major parts or subdivisions:

  1. The central nervous system (CNS) consists of the brain & spinal cord.
  2. The peripheral nervous system (PNS), which consists of cranial nerves and spinal nerves.

The central nervous system (CNS)

Nervous system

The brain

The brain consists of many parts that function as an integrated system. The major parts are the cerebrum (cerebral cortex), cerebellum, basal ganglia, brain stem (midbrain, pons, and medulla), the thalamus, and the hypothalamus.

Spinal cord

In cross-section, the spinal cord shows a central butterfly-shaped area of grey matter with 3 projections called horns: dorsal, lateral, and ventral, The grey matter is surrounded by white matter, which consists of groups of myelinated axons.

These groups of fibers run longitudinally through the cord, some descending to relay information from the brain to the spinal cord, others ascending to transmit information to the cortex. The spinal cord is divided into 31 segments with a pair of spinal nerves arising from each segment. Each spinal nerve arises from the spinal cord by 2 roots:

  • Dorsal (afferent sensory) root: fibers of which originate in the periphery from sensory receptors and terminate in the dorsal horn. the cell bodies of these afferent fibers are located outside the spinal cord in clusters called dorsal root ganglia.
  • Ventral (efferent motor) root: Fibers of which originate in the ventral horn and travel to the periphery where they form synapses with skeletal muscles.

The connection between neurons inside the CNS is called a synapse. Synapse is the site of contact between 2 neurons i.e. the site of contact between the axon terminals of one neuron and the cell body or dendrites of another neuron. (there is no cytoplasmic continuity between neurons).

The peripheral nervous system

It includes cranial and spinal nerves, the peripheral nervous system is either somatic or autonomic. The somatic nervous system controls the voluntary movements of the skeletal muscle. The autonomic nervous system is divided into the sympathetic and parasympathetic nervous system and controls the action of the internal organs and glands. i.e. functions of the heart, glands, and viscera.

Neurons of the peripheral nervous system (PNS) that conduct impulses away from the central nervous system (CNS) are known as the motor or efferent neurons. The unit structure of the nervous system is the nerve cell (neuron). There are two major categories of motor neurons:

  1. Somatic motor neurons have their cell bodies within the CNS (anterior horn cell) and send axons to skeletal muscles, which are usually under voluntary control. It is a thick myelinated type Aα fiber with fast conduction of about 100m/sec.
  2. Autonomic motor neurons: involves two neurons in the efferent pathway: preganglionic and post-ganglionic neurons with autonomic ganglia in between.

Reflex action

It is an unavoidable beneficial inborn response brought about by a stimulus (a sudden change of the external or internal environment.

Types of reflex action

  1. Somatic reflex action: when the responding tissue is the skeletal muscle.
  2. Autonomic reflex action: concerned with reflexes of internal organs or viscera such as gastrointestinal tract, urinary bladder … etc.

Reflex Arc is the pathway of reflex action. It consists of 5 different components:

Receptor → Afferent neuron → center → efferent neuron → effector organ.

Functional organization of the autonomic nervous system

The autonomic nervous system (ANS) is the part of the nervous system that is responsible for homeostasis, the Autonomic motor nerves innervate the organs whose functions are not usually under voluntary control.

Divisions of the autonomic nervous system

Anatomically:

  • Cranial outflow (cranial nerves III, VII, IX, and X).
  • Thoraco-lumbar outflow (from T1- L2).
  • Sacral outflow (sacral 2,3 and 4).

Functionally:

  1. The sympathetic nervous system (thoraco-lumbar from T1-L2).
  2. The parasympathetic nervous system (cranio- sacral) including:
  • Cranial nerves III, VII, IX and X.
  • Sacral 2,3 and 4.

Autonomic ganglia

As previously mentioned, the peripheral efferent portions of the autonomic nervous system are made up of preganglionic and postganglionic neurons.

  • The preganglionic neuron has its cell body in the gray matter of the brain or spinal cord (lateral horn cell). The axon of this neuron does not directly innervate the effector organ but instead synapses with a second neuron within an autonomic ganglion. This neuron is a thin myelinated type B fiber with a conduction velocity of about 10 m/sec.
  • The postganglionic neuron is the second neuron in this pathway, which has an axon that extends from the autonomic ganglion to an effector organ, where it synapses with its target tissue. It is thin unmyelinated C fiber with a velocity of conduction of about 1 m/sec.

The autonomic ganglion is an aggregation of cell bodies of neurons outside the CNS. In the sympathetic system, the preganglionic fibers relay mainly in ganglia located near the spinal cord. On the other hand, in the parasympathetic system, the preganglionic fibers relay in ganglia present close to or even embedded in the effector organs. Each preganglionic fibre relays once only, though it may pass through several ganglia.

Types of autonomic ganglia

  1. Lateral (parvertebral) ganglia.
  2. Collateral (prevertebral) ganglia.
  3. Terminal (peripheral) ganglia.

Lateral ganglia

The lateral ganglia lie on each side of the vertebral column forming two chains known as sympathetic chains (the lateral ganglia are the sites of the relay of sympathetic fibers).

The sympathetic chain contains one ganglion for each segmental nerve, except in the cervical region, where individual ganglia become variably fused to form three ganglia: the superior, middle, and inferior cervical ganglia.

Collateral ganglia

Collateral ganglia lie between the sympathetic chain & the organ of supply. They are the site of the relay of the preganglionic sympathetic fibers that supply the abdominal and pelvic viscera.

Terminal ganglia

  • They are present near (or on the surface) of the innervated organs.
  • They are the sites of relay of the parasympathetic fibers.

Functions of the autonomic ganglia

The ganglia act as distributing centers:

  • In the sympathetic system, the preganglionic fiber synapses with and activities many postganglionic neurons. This allows for widespread distribution of nerve impulses over wide areas of the body thus producing generalized sympathetic effects.
  • In the parasympathetic, the preganglionic fiber synapses with and activates only a few postganglionic neurons. Therefore, this arrangement produces localized and discrete parasympathetic activities.

Site of relay: Autonomic ganglia are stations for relay of preganglionic fibers coming from CNS.

Site of release of chemical transmitter: Acetylcholine is the mediator liberated at all preganglionic endings (sympathetic and parasympathetic). It is responsible for the transmission of the nerve impulse from preganglionic to postganglionic neurons (synaptic transmission).


Frequently Asked Questions: Reproduction

Q. How many eggs can a fly lay at a time? How often does a female lay the eggs?
A. A housefly lays about 100 eggs every two weeks.

Q. Are there any male animals that become pregnant?
A. There is a fish called a seahorse that makes sperm and is therefore regarded as male. However, the male seahorse also develops a pouch on its belly a few days before mating with a female. The female squirts eggs into the pouch and the male incubates in the pouch for two weeks.

Q. Do you need a rooster in a hen-house to get eggs?
A. No. Many of the eggs we purchase from the local supermarket are unfertilised eggs, that is, eggs laid by female chickens that have not mated with a male rooster. Unfertilised eggs will never grow into chickens.
If a chicken farmer wants to breed chickens, a male rooster must mate with a female hen to make fertilised eggs. These will then grow into chickens if they are looked after.

Q. Does it hurt when a baby's umbilical cord is cut after birth?
A. No. There are no nerve receptors to sense pain in the umbilical cord. Nor should there be much bleeding because the blood flow ceases in the cord before birth because the baby will have its own functioning blood supply.

Q. What would happen if a marine sponge was sliced into pieces by a boat's propeller?
A. Sponges reproduce asexually. Each fragment of the sponge will grow into a new organism.

Q. When was the first 'test-tube' baby born?
A. The first 'test-tube' baby born was Louise Brown in 1978.

Q. What causes 'innie' and 'outie' belly buttons?
A. The difference between an 'innie' and an 'outie' belly button or navel depends on the point at which the umbilical cord was cut just after birth.


Researchers convert skin and umbilical cord cells directly into nerve cell

Nerve cells made from skin cells: The cells have been dyed green by means of an antibody. The cell nucleus attains a blue color. Photo: Julia Ladewig/Uni Bonn

Until recently, the production of pluripotent "multipurpose" stem cells from skin cells was considered to be the ultimate new development. In the meantime, it has become possible to directly convert cells of the body into one another – without the time-consuming detour via a pluripotent intermediate stage. However, this method has so far been rather inefficient. Scientists from the Bonn Institute of Reconstructive Neurobiology have now developed the method to the point that it can be used for biomedical applications. The scientists are presenting their results in the journal Nature Methods.

There was much excitement surrounding cell reprogramming with the breakthrough of Shinya Yamanaka. In 2006, the Japanese scientist was able to reprogram skin cells for the first time with the aid of a few control factors into so-called induced pluripotent stem cells (iPS cells) – "multipurpose" cells from which all body cells can in principle be produced. In 2010, Marius Wernig, a former postdoctoral researcher with Prof. Brüstle and meanwhile the director of the institute at Stanford University in California, developed the idea further: Using only three so-called transcription factors, his team was able to perform direct transformation of skin cells into so-called induced neurons (iN). However, the method has so far been rather inefficient: Only a small percentage of the skin cells were converted into the desired nerve cells.

Researchers are increasing yields during transformation of cells

For the scientists at the LIFE & BRAIN Center at the University of Bonn, that was not enough. They are interested in the biomedical utilization of artificially produced human nerve cells for disease research, cell replacement, and the development of active substances. One concept seemed likely: Why not use low-molecular active substances - so-called small molecules - to optimize the process? Julia Ladewig, post-doctoral researcher and lead author of the study, began using such active substances to influence several signaling pathways important for cell development.

By blocking the so-called SMAD signaling pathway and inhibiting glycogen synthase kinase 3 beta (GSK3ß), they increased the transformational efficiency by several times – and were thus able to even simplify the means of extraction. Using only two instead of previously three transcription factors and three active substances, the Bonn researchers were able to convert a majority of the skin cells into neurons. In the end, their cell cultures contained up to more than 80% human neurons. And since the cells divide even further during the conversion process, the actual efficiency is even higher.

Two nerve cells are produced from one skin cell

"We can obtain up to more than 200,000 nerve cells converted in this way from 100,000 skin cells," says Julia Ladewig. In order to find the right combination of active substances, the Bonn scientists are focusing on signaling pathways which are especially important for cell specialization. "The SMAD signaling pathway and also GSK3ß were suspected of inhibiting the conversion of connective tissue cells and pluripotent stem cells into neural cells. The obvious step was to block both of them using corresponding active substances," says Philipp Koch, team leader and senior author responsible for the study, together with Prof. Brüstle. The results were intriguing: "We were able to demonstrate how the genes typical for skin fibroblast were gradually down-regulated and nerve-cell-specific genes were activated during the cell transformation. In addition, the nerve cells thus obtained were functionally active, which also makes them interesting as a source for cell replacement," says Ladewig.

Scientists are now transferring the method to other types of cells

The Bonn scientists have already transferred the method to other types of cells such as, for example, umbilical cord cells. Brüstle clearly foresees the next steps: "First of all, we want to use nerve cells obtained in this way for disease and active substance research. The long-term goal will be to convert cells directly in the body into nerve cells."


Signature’s Comments

I spoke to Dan Wagner from Signature Biologics who didn’t believe that a white paper claiming that the product had stem cells was an issue. This is what he sent me:

“Signature Biologics designed our products to be in compliance with CFR 1271 Section 361 as outlined in the Guidance issued by FDA in Nov/Dec 2017. The product you have referenced, Signature Cord, is prepared with minimal manipulation, is intended for homologous use only as a supplemental cushioning agent by a licensed health care provider, does not involve combination of cells or tissues with any other article (except for crystalloids and preserving/storage agents which do not raise new clinical safety concerns) and our products do not have a systemic effect and are not dependent upon the metabolic activity of living cells for its primary purpose.”


Carla Hernandez Guided questions

Opening Questions How did the simulated experience of Carla Hernandez’s case make you feel? - I felt really nervous, especially when the patient was moaning. This simulation gave me an amazing experience with umbilical cord prolapse when the baby needs interventions right away to stay alive. Describe the actions you felt went well in this scenario. The actions that went well in this scenario: - Calling the provider, and the surgeon team to get her ready for a C-section. - Giving her Terbutaline to slow down her contractions - Giving Lactated Ringer’s 500 mL IV bolus for abnormal FHR - Comforting her - Repostioning the baby to release pressure on the umbilical cord.

Scenario Analysis Questions 1 EBP Consider the emergent nature of umbilical cord prolapse. What nursing actions should be initiated immediately? Why? Immediately wear sterile glove and place hand into patient's vagina to push the fetus off the umbilical cord so that the baby can get enough oxygen. Contact surgical team and physician for an emergency C-section. PCC What is the priority need for Carla Hernandez at this time?

1 The Scenario Analysis Questions are correlated to the Quality and Safety Education for Nurses (QSEN) competencies: Patient-Centered Care (PCC), Teamwork anQuality Improvement (QI), Safety (S), and Informatics (I). Find more information at: d Collaboration (T&ampC), Evidence-Based Practice (EBP), http://qsen.org/

From vSim for Nursing | Maternity and Pediatric. © Wolters Kluwer Health.

Repositioning her: knee-to-chest, trendelenburg, hips higher than chest, modified Sims to release compression on umbilical cord. Making sure the baby gets enough O2, preventing fetal complications, attaching non-rebreather mask for her, administering Terbulatine to slow down her contraction and getting everything ready for C-section.

T&ampC What key elements would you include in the handoff report for this patient? Consider the situation-background-assessment-recommendation (SBAR) format.

  • She is having umbilical cord prolapse which is causing the baby to have bradycardia. FHR was only 105 bpm, I already push the baby off the cord.
  • The provider broke her water
  • Her vital signs are stable: BP 140/82, P 90 bpm, RR 15, Sp02 97, T 99.
  • Her pain level is 2/10.

S/QI/I Based on your experience with Carla Hernandez’s case, reflect on possible nursing actions for enhanced safety and quality improvement. In emergency situations like this, a nurse should know what to prioritize when assessing the patient to enhance safety and quality improvement. Monitoring both mother and fetal heart rate, assessing the vagina, asking how the mother feels should be the nurse’s prioritization.

Concluding Questions Reflecting on Carla Hernandez’s case, were there any actions you would do differently? Explain. I would have prioritized assessing the fetal heart rate and assessed the patient’s vagina to see what was happening to her the baby and assessed why the baby was experiencing bradycardia. Describe how you would apply the knowledge and skills that you obtained in Carla Hernandez’s case to an actual patient care situation. I would be really careful about administering the patient pain medication, especially in this case when the FHR is dropping so opioids like will make the situation worse.

From vSim for Nursing | Maternity and Pediatric. © Wolters Kluwer Health.


Watch the video: Κατέρρευσε Αυστριακή βουλευτής αν και ήταν εμβολιασμένη - Κατά την διάρκεια της ομιλίας της (January 2022).