Human form and function 3

Question 1

What do the adrenal cortex hormones mediate?

Answer 1

Long term stress responses

Question 2

What is the adrenal cortex hormone function ?

Answer 2

participate in homeostatic regulation of metabolism.

Question 3

What is the function of the glucocorticoids?

Answer 3

Glucocorticoids have a main effect on glucose metabolism and promote glucose synthesis from non-carbohydrate sources such as protein and fat so that more glucose is available in the blood circulation for cellular energy production.

These hormones can promote breakdown
of skeletal muscle proteins for synthesis of glucose when the body requires more glucose.

Question 4

what is the main glucocorticoid?

Answer 4

cortisol

Question 5

Main mineralocorticoid of adrenal cortex by adrenal gland

Answer 5

aldosterone

Question 6

Adrenaline medulla hormones

Answer 6

The hormones produced in the adrenal medulla are adrenaline (epinephrine) and noradrenaline
(norepinephrine) which could mediate ‘short term stress responses

Question 7

Upon extensive sympathetic nervous stimulation, What is the function of adrenal medulla hormones?

Answer 7

Secretes these hormones which can potentiate the “fight
or flight response” by increasing the heart rate and blood pressure, diverting blood to essential
organs (i.e heart, brain, skeletal muscles) and increasing metabolic rate.

The hormones secreted
by adrenal medulla are mainly involved in increasing the availability of chemical energy for
immediate use.

These hormones promote glucose release into the circulating blood by increasing
the rate of glycogen breakdown (in liver and skeletal muscles) and fatty acids release (from fat
cells) for energy production within the body cells.

Question 8

What are the features of islets of Langerhans of the pancreas?

Answer 8

Pancreases can be considered an endocrine gland as well as an exocrine gland. It is located behind the stomach in the curve of the duodenum.

The endocrine part of the pancreas is the islets of
Langerhans which are clusters of cells scattered throughout the pancreas.

These pancreatic islets mainly secrete two hormones, glucagon and insulin which control the blood glucose level by opposing actions.

Alpha cells of the pancreatic islets secrete glucagon which mainly promote the blood glucose level increase.

Beta cells of the pancreatic islets secrete insulin which promotes
lowering of blood glucose level.

Question 9

What are the main target sites of the pancreatic hormones?

Answer 9

Liver and skeletal muscles are the main target sites of these
hormones

Question 10

What is the female gonad location?

Answer 10

pelvic cavity

Question 11

Where do the paired male gonads lie in?

Answer 11

Paired male gonads (testes) lie in
the scrotum.

Question 12

What are the functions of the ovaries and the testis?

Answer 12

In addition to the reproduction, ovaries and testes have endocrine functions.

Question 13

What does the ovarian follicle and corpus luteum produce?

Answer 13

Ovarian follicle produces the hormone estrogen. Corpus luteum (the structure formed from
the ovarian follicle after ovulation) produces progesterone.

Question 14

What are the functions of LH and FSH?

Answer 14

These female sex hormones along
with FSH and LH from the anterior pituitary regulate menstrual cycle, maintain pregnancy and
prepare mammary glands for lactation. They also help establish and maintain feminine sexual
characteristics. The ovaries also produce the hormone inhibin that inhibits secretion of FSH from
anterior pituitary.

Question 15

What are the locations and the functions of the male sex hormones?

Answer 15

The main hormone produced and secreted by the testes (interstitial cells) is the male sex hormone,
testosterone. Testosterone regulates production of sperm and stimulates the development and
maintenance of masculine secondary sex characteristics. In addition, the testes (Sertoli cells)
produce inhibin that inhibits secretion of FSH.

Question 16

Example for negative feedback mechanism of glucose metabolism?

Answer 16

In the absence of stimulation, the blood level of hormone will
decrease. Some hormone levels in the blood can be directly controlled by the blood levels of
the stimulus (e.g. insulin or glucagon by blood glucose levels). For example high blood glucose
levels stimulate the release of insulin hormone (from the pancreas) to the circulating blood which
acts on specifi c target tissues to lower the blood glucose level. When glucose level in the blood
reaches normal range, blood glucose level can in turn directly control the secretion of insulin
levels from the pancreas and prevent further lowering of the glucose level in the blood.

Question 16

Example for negative feedback mechanism?

Answer 16

In the absence of stimulation, the blood level of hormone will
decrease. Some hormone levels in the blood can be directly controlled by the blood levels of the stimulus (e.g. insulin or glucagon by blood glucose levels).

For example high blood glucose levels stimulate the release of insulin hormone (from the pancreas) to the circulating blood which acts on specific target tissues to lower the blood glucose level.

When glucose level in the blood reaches normal range, blood glucose level can in turn directly control the secretion of insulin
levels from the pancreas and prevent further lowering of the glucose level in the blood.

Question 17

Give an example for positive feedback mechanism

Answer 17

Positive feedback mechanisms involving oxytocin
hormone operate in childbirth and breast milk ejection

Question 18

How do the positive feedback mechanisms occur? (1 way)

Answer 18

During labour, contractions of uterus are stimulated by oxytocin hormone released by the posterior pituitary. These contractions force the baby’s head into the uterine cervix stimulating its stretch receptors.
In response to stimulation
of stretch receptors, sensory neurons are stimulated again triggering more oxytocin release from
the posterior pituitary enhancing contractions of the uterus. This process repeats until the baby is
born. Afterwards oxytocin secretion stops as the stimulus

Question 19

Name another way of positive feedback mechanism

Answer 19

During suckling, sensory neurons send the nerve impulses to the
posterior pituitary triggering release of oxytocin hormone to the circulating blood. Then oxytocin
acts on the mammary glands and induces contractions of smooth muscles in the mammary
glands to release milk. Milk release increases the sensory stimulus forming a positive feedback
that amplifi es the stimulus. In response to the positive feedback, more oxytocin is released
enhancing milk ejection

Question 20

Name heat loss mechanisms

Answer 20

• dilation of blood vessels in the skin which causes fi lling of blood capillaries with warm
  blood and radiating heat from the skin surface
• increase sweat secretion from the sweat glands which promotes heat dissipation through
  evaporative cooling

Question 21

Name heat gain mechanims

Answer 21

constriction of blood vessels in the skin which divert the blood from the skin to deeper
tissues thereby reducing heat loss through the skin surface
- shivering: rapid repetitive contractions of skeletal muscles to generate heat
- contracting hair erector muscles to generate heat to some extent
- stimulating secretions of more thyroid hormones (e.g. thyroxin) and adrenalin into the
blood which increase the metabolic rate and cellular metabolism (especially oxidation of
fat in the liver) to produce more heat

Question 22

When the blood glucose level rise up over the normal range?

Answer 22

High blood glucose levels exceeding the normal limits, stimulate the secretion of insulin hormone from beta cells of the islets of Langerhans into the circulating blood. Insulin acts on specific target tissues to promote lowering of the blood glucose level.

Insulin in the circulating blood stimulates transport of glucose into the body cells and use of glucose by body cells for ATP production
(glucose may be broken down into carbon dioxide and water), conversion of glucose to glycogen in liver and skeletal muscle cells for storage, and conversion of glucose to fatty acids and storage
of fat in adipose tissues.

When glucose level in the blood reaches normal range, blood glucose
level can in turn directly control the secretion of insulin levels from the pancreas through negative
feedback. This mechanism prevents further lowering of the glucose level in the blood beyond the
normal limits.

Question 23

When the glucose levels are below the normal limits, what happens?

Answer 23

Low blood glucose levels below the normal limit, stimulate the secretion of glucagon from alpha cells of the islets of Langerhans into the circulating blood.

Glucagon acts on specific target tissues to promote increase of the blood glucose level.

Glucagon promotes the breakdown of glycogen in the liver and skeletal muscles and release of glucose into blood.

When glucose level in the blood reaches normal range, blood glucose level can in turn directly control the secretion of glucagon levels from the pancreas through negative feedback which prevents further increasing of the glucose level in the blood beyond the normal limits.

Question 24

What happens when blood level increases beyond the normal limits?

Answer 24

Low blood glucose levels below the normal limit, stimulate the secretion of glucagon from alpha cells of the islets of Langerhans into the circulating blood. Glucagon acts on specifi c target tissues to promote increase of the blood glucose level. Glucagon promotes the breakdown of glycogen in the liver and skeletal muscles and release of glucose into blood. When glucose level in the blood reaches normal range, blood glucose level can in turn directly control the secretion of glucagon levels from the pancreas through negative feedback which prevents further increasing of the glucose level in the blood beyond the normal limits.

Question 25

What are the ways by which the blood osmotic level is obtained?

Answer 25

controlling the amount of water and controlling the amount of salt gained and lost by the body.

Question 25

What are the ways by which the blood osmotic level is obtained?

Answer 25

controlling the amount of water and controlling the amount of salt gained and lost by the body.

Question 26

What happens when blood osmolarity is increased beyond the normal limits?

Answer 26

When blood osmolarity is increased beyond the physiological limits, it is sensed by the osmoreceptors in the hypothalamus which stimulates the posterior pituitary to release ADH to the blood circulation. ADH acts on the kidney tubules and stimulates the reabsorption of water through distal convoluted tubules of the nephrons and collecting ducts producing concentrated urine. When blood osmolarity is decreased, ADH is not secreted, so water reabsorption through distal convoluted tubules of the nephrons and collecting ducts stop thereby producing diluted urine. In addition, low blood volume and low blood sodium ions stimulate the kidneys to produce angiotensin II which stimulates the adrenal cortex to secrete aldosterone hormone. Aldosterone stimulates the reabsorption of sodium ions by the kidney tubules which is accompanied by the water retention, thereby increasing blood volume and blood pressure. Hence, kidneys play a major role in osmoregulation in the human body.

Question 27

What is the role of liver in homeostasis?

Answer 27

Carbohydrate metabolism Fat metabolism Protein metabolism Breakdown of erythrocytes and defense against microbial infections Detoxification of drugs and toxicants: Production of heat Storage of nutrients Inactivation of hormones Secretion of bile

Question 28

What are the ways of asexual reproduction?

Answer 28

Budding Fragmentation and regeneration Parthenogenesis

Question 29

Explain what happens during budding

Answer 29

Budding is a form of asexual reproduction in which new individuals arise form outgrowths of the animal. e.g. Hydra – A localized mass of mitotically dividing cells, develops into a small Hydra, which can eventually detach from the parent.

Question 30

What happens during fragmentation and regeneration?

Answer 30

This is a form of asexual reproduction which involves breaking of the body or part of the body into several pieces, followed by the growth of a separate individual from each piece. Each fragment develops into a complete animal by regrowth of lost body parts (regeneration). e.g. Certain annelid worms, numerous sponges, cnidarians.

Question 31

What takes place during parthenogenesis?

Answer 31

This is an unusual form of asexual reproduction in which an egg develops into a complete individual without being fertilized. Among invertebrates, parthenogenesis occurs in some animals such as bees, ants, aphids and wasps. The progeny can be haploid or diploid. In honey bees – males (drones) are fertile haploid adults that develop through parthenogenesis, whereas females including both sterile workers and the fertile queen, are diploid adults that developed from fertilized eggs. Parthenogenesis has also been observed very rarely among vertebrates (e.g. some lizards and fi sh).

Question 32

Describe the nature of the female gamete during the sexual reproduction?

Answer 32

the egg, is large and non-motile

Question 33

Describe the nature of the male gamete during sexual reproduction?

Answer 33

the sperm, is generally much smaller and motile.

Question 34

Describe about gamete formation during sexual reproduction

Answer 34

In animals, reproductive cells called gametes (sperms and eggs) are the vehicles that transmit genes from one generation to the next. Each gamete is a haploid, unicellular reproductive cell. Gametes in animals are formed by meiosis in special organs called gonads.

Question 35

What are bisexual organisms?

Answer 35

n a bisexual organism (Hermaphrodite), one individual has both female and male reproductive structures and therefore is able to produce both male and female gametes by the same individual. e.g. Earthworms

Question 36

Explain about unisexual organisms

Answer 36

*In unisexual organisms (dioecious), one individual bears either male or female reproductive structures. *Therefore production of male or female gametes occurs in separate organisms. e.g. Humans

Question 37

What are the requirements for the external fertilization?

Answer 37

*occurs in aquatic environments. *In species with external fertilization, the female releases eggs while the male releases sperm into the external environment and fertilization occurs in the water. A moist habitat is almost always required for external fertilization both to prevent the gametes from drying out and to allow the sperm to swim toward the eggs. e.g. Many invertebrates, amphibians, most bony fish.

Question 38

What are organisms that show internal fertilization?

Answer 38

insects, reptiles, mammals.

Question 39

Explain about the internal fertilization

Answer 39

Internal fertilization is an adaptation that enables sperm to reach an egg even when the environment is dry. The male copulatory organ delivers sperm and the female reproductive tract often has receptacles for storage and delivery of sperm to mature eggs. Internal fertilization is typically associated with the production of fewer gametes than external fertilization but results in the survival of a higher fraction of zygotes. Internal fertilization often provides greater protection to the embryos. Many animals show parental care. Internally fertilized eggs of birds and other reptiles possess shells and internal membranes that protect against water loss and physical damage. Some retain the embryo for a portion of any development within the female reproductive tract.

Question 40

What are the advantages of asexual reproduction?

Answer 40

Asexual reproduction allows rapid multiplication of individuals from single parents. Hence no time or energy is needed to be spent in searching mates for the reproduction. In asexual reproduction, there is no or very little genetic variation within a population as the produced off spring are genetically identical to each other and to the single parent. Therefore, asexual reproduction would be more advantageous in stable, favorable environments as it can propagate successful genotypes specifi cally. However, any mutation in the parent cell, can cause harmful eff ects on the survival ability of the off spring in changing environments. If there is a harmful mutation in the organisms, environment changes could be deadly to all the individuals in the population.

Question 41

Advantages of sexual reproduction

Answer 41

Unlike asexual reproduction, sexual reproduction results in the production of a unique off spring by combining genetic materials from two parents. Meiotic recombination during sexual reproduction helps produce varied genotypes. Unique gene combinations formed during sexual reproduction would be advantageous as this can enhance reproductive success and survival of a species in changing environments. Benefi cial gene combination arising through recombination may speed up adaptation. During sexual reproduction, shuffl ing of genes might allow a population to clear sets of harmful genes more readily which would enhance the survival of the species.

Question 42

What are the functions of the reproductive organs of the reproductive system?

Answer 42

gonads (testes) which produce sperm and reproductive hormones, epididymis which store mature sperms, accessory glands that secrete products required for sperm movement ducts that transport the mature sperm and glandular secretions

Question 43

What are the external male reproductive organs?

Answer 43

The external reproductive organs of a male are the scrotum and penis.

Question 44

Function of the sertoli cells?

Answer 44

These cells secrete the hormone inhibin and nourish and provide attachment for cells that are in different stages of spermatogenesis

Question 45

What is the function of the leydig cells?

Answer 45

secrete the hormone testosterone and other androgens after puberty which promote spermatogenesis in the tubules

Question 46

What is the function of the epididymis?

Answer 46

Matured sperms are stored within the epididymis until ejaculation.

Question 47

What does the urethra run through?

Answer 47

The urethra runs through the penis and opens to the outside at the tip of the penis which contains erectile tissues derived from modifi ed veins and capillaries.

Question 48

What is the function of the ejaculatory duct?

Answer 48

The ejaculatory ducts open into the urethra which is the passageway for both urinary excretion and delivery of sperms in semen into the female reproductive tract

Question 49

Explain the basic process of spermatogenesis?

Answer 49

formation of spermatocytes from a spermatogonium, meiotic division of the spermatocytes, and transformation of the four resulting spermatids (from each spermatocyte) into spermatozoa (sperm)

Question 50

Explain about the sperm

Answer 50

Each sperm is made up of three main parts, the head, midpiece (body) and tail. Head of the sperm contains the haploid nucleus carrying the paternal genetic material. A special vesicle called the acrosome is present at the anterior end of the head. It contains hydrolytic enzymes such as trypsin and hyaluronidase that help the sperm to penetrate the outer layers of the ovum. Midpiece of the sperm contains many mitochondria that provides ATP necessary for the movement of the tail. The tail of the sperm contains a long fl agellum with typical 9+2 arrangement of microtubules. It is produced by the centriole found near the base of the nucleus. The tail enables the sperm to swim along the female reproductive tract towards an ovum.

Question 51

What does the semen contain?

Answer 51

Main fraction of the semen is made up of secretions from seminal vesicles and the prostate gland. The semen contains several components such as mucus, enzymes, prostaglandins, ascorbic acid, citrate and fructose which promote the survival of sperm.

Question 51

What does the semen contain?

Answer 51

Main fraction of the semen is made up of secretions from seminal vesicles and the prostate gland. The semen contains several components such as mucus, enzymes, prostaglandins, ascorbic acid, citrate and fructose which promote the survival of sperm.

Question 52

What is the function of the semen?

Answer 52

The semen provides a liquid medium for the sperm movement and also helps to neutralize the acidity in the female reproductive tract.

Question 53

What kind of fluid does the seminal vesicle produce?

Answer 53

They are a pair of two small pouches that produce a thick, yellowish fluid that is expelled during ejaculation

Question 54

What is the function of the seminal fluid?

Answer 54

Seminal fluid is alkaline to protect the sperm in the acidic environment of the vagina.

Question 55

What does the seminal fluid contain?

Answer 55

mucus, fructose (that provides most of the sperm’s energy), a coagulating enzyme (helps semen coagulates after ejaculation), ascorbic acid and local regulators called prostaglandins. This fluid contributes to about 60% of the volume of semen.

Question 56

What does the each seminal vesicle open into?

Answer 56

Each seminal vesicle opens into a short duct that joins the corresponding vas deference to form an ejaculatory duct.

Question 57

Where can the prostate gland be found in?

Answer 57

This gland is found below the urinary bladder

Question 58

What does the prostate gland secrete?

Answer 58

It secretes a thin, milky fluid directly into the urethra through small ducts

Question 59

What does the prostate gland secretions contain?

Answer 59

This milky secretion contains coagulants, anticoagulant enzymes and citrate which is a sperm nutrient. This fluid contributes to about 30% of the volume of semen.

Question 60

What does the pair of bulbourethral gland contain?

Answer 60

They are a pair of small glands found along the urethra below the prostate.

Question 61

What does the bulbourethral gland secrete?

Answer 61

These glands secrete a clear alkaline mucus that is able to neutralize any acidic urine remaining in the urethra and lubricates the lining of the urethra.

Question 62

Describe the hormonal control of the human male reproductive system.

Answer 62

· In males, in response to the release of GnRH from the hypothalamus (just before puberty), results in the release of FSH and LH by the anterior pituitary. Rising levels of the FSH and LH hormones at puberty promotes mature functioning of the male reproductive organs. The hormones regulate the development, growth, pubertal maturation and reproductive processes of the body. · FSH and LH hormones direct spermatogenesis by acting on different types of cells in the testis. · FSH stimulates Sertoli cells to nourish the developing sperm. · LH causes Leydig cells to produce testosterone and other androgens to promote spermatogenesis. · Two negative-feedback mechanisms control sex hormone production in males. · Testosterone inhibits GnRH, FSH and LH in blood through its eff ect on the hypothalamus and anterior pituitary. · Additionally inhibin produced by Sertoli cells, acts on anterior pituitary gland to reduce FSH secretion. · These negative-feedback circuits maintain testosterone and other androgen levels in the normal range.

Question 63

What are the female gonads?

Answer 63

ovaries

Question 64

What are the steps of human development?

Answer 64

Fertilization/conception and the formation of a human zygote Cleavage of the zygote, blastocyst formation and implantation Embryonic members / fetal membranes Placenta and umbilical cord

Question 65

Describe the steps up to puberty of oogenesis?

Answer 65

· Oogenesis begins in the female embryo with the mitotic division of primordial germ cells that give rise to oogonia. · Then oogonia divide by mitosis to form cells that begin meiosis, but stops at prophase I before birth. · Each of these developmentally arrested cell is called a primary oocyte. Each primary oocyte is found within a small follicle, a cavity lined with protective cells. At birth, the ovaries together contain about 1-2 million primary oocytes. Out of these about 500 fully mature between the puberty and the menopause.

Question 66

What happens at the beginning of the puberty of females during oogenesis process?

Answer 66

· Beginning at puberty, follicle stimulating hormone (FSH) periodically stimulates a small group of follicles to resume growth and development. Out of these only one follicle fully matures each month. During this time the primary oocyte within the follicle completes meiosis I and produces a secondary oocyte and the fi rst polar body. Then the meiosis II starts, but stops at the metaphase. · The secondary oocyte arrested in meiosis II is released at ovulation (with the fi rst polar body), when its follicle breaks open. · If a sperm penetrates the secondary oocyte, meiosis II completes and the secondary oocyte divides into the mature ovum and a second polar body. Both meiotic divisions involve unequal cytokinesis, with the smaller cells becoming polar bodies which will degenerate eventually. If a sperm penetrates, there is a single mature egg (ovum) containing a sperm head at the end of oogenesis. The fusion of the haploid nuclei of the sperm and the ovum is called fertilization.

Question 67

What takes place after the process of ovulation?

Answer 67

· The ruptured follicle left behind after ovulation develops into the corpus luteum. Corpus luteum secretes estradiol and progesterone hormones which help to maintain the uterine lining during pregnancy. · If the egg is not fertilized, the corpus luteum degenerates and leaves a small ,permanent scar of fi brous tissue called corpus albicans on the ovary surface. · A new follicle matures during the next cycle.

Question 68

Briefly mention the facts of Hormonal control of the human female reproductive cycles?

Answer 68

Although males produce sperms continuously, females produce ova in cycles. There are two linked reproductive cycles in a human female during their reproductive years; the ovarian cycle and the uterine cycle (or the menstrual cycle). The uterine cycle consists of changes that occur about once a month in the uterus and these cyclic changes in the uterus are controlled by the ovarian cycle, which is cyclic events that occur in the ovaries. Both of these cycles are regulated by hormonal activities which link the two cycles, synchronizing ovarian follicle growth and ovulation with the establishment of a uterine lining which supports the development of embryo.

Question 68

Briefly mention the facts of Hormonal control of the human female reproductive cycles?

Answer 68

Although males produce sperms continuously, females produce ova in cycles. There are two linked reproductive cycles in a human female during their reproductive years; the ovarian cycle and the uterine cycle (or the menstrual cycle). The uterine cycle consists of changes that occur about once a month in the uterus and these cyclic changes in the uterus are controlled by the ovarian cycle, which is cyclic events that occur in the ovaries. Both of these cycles are regulated by hormonal activities which link the two cycles, synchronizing ovarian follicle growth and ovulation with the establishment of a uterine lining which supports the development of embryo.

Question 69

What happens during menopause?

Answer 69

During this time the ovarian supply of oocytes runs out and the estrogen production by the ovary decreases. Ovaries become less responsive to the hormones FSH and LH produced by the anterior pituitary.

Question 70

What happens during human development?

Answer 70

Fertilization/conception and the formation of a human zygote Cleavage of the zygote, blastocyst formation and implantation

Question 71

Where is the glycoprotein in the oocyte?

Answer 71

the glycoprotein layer present between the oocyte’s plasma membrane and the surrounding cells.

Question 72

Where does fertilization occurs?

Answer 72

Fertilization takes place in the upper reaches of the oviduct within 12 to 24 hours after ovulation.

Question 73

How does the morula get nutrition?

Answer 73

endometrial secretion

Question 74

What are the distinct layers of the blastocyst?

Answer 74

Inner cell mass trophoblast

Question 75

How does the trophoblast invade the endometrium?

Answer 75

The trophoblast grows outward and invades the endometrium. This is initiated by the enzyme secreted by the trophoblast to breakdown the uterine lining. Then the trophoblast extends finger like projections into the endometrium.

Question 76

What does the trophoblast secrete?

Answer 76

Trophoblast begins to secrete human chorionic gonadotropin (hCG) hormone which has the action similar to LH. The hormone hCG rescues the corpus luteum from degeneration and sustains its secretion of progesterone and estrogen which maintain the uterine lining preventing menstruation.

Question 77

What happens after the end of gastrulation stage?

Answer 77

After implantation, three germ layers are formed in the developing embryo at the end of the gastrulation stage. Extra-embryonic membranes begin to appear which surround the embryo. The placenta is formed by the cells of trophoblast and the adjacent endometrial tissues.

Question 78

Chorion functions?

Answer 78

the main embryonic portion of the placenta which is the structure for exchange of materials between the fetus and mother. It also protects the embryo/fetus from immune responses of the mother. Chorion produces hCG, an important hormone of pregnancy

Question 78

Chorion functions?

Answer 78

the main embryonic portion of the placenta which is the structure for exchange of materials between the fetus and mother. It also protects the embryo/fetus from immune responses of the mother. Chorion produces hCG, an important hormone of pregnancy

Question 79

Amnion functions?

Answer 79

protective membrane surrounding the embryo/fetus creating a fluid filled cavity which serves as a shock absorber and helps prevent desiccation.

Question 80

Yolk sac functions

Answer 80

Yolk sac contributes to the cells that will become blood cells until the fetal liver takes over. It also is the source of primordial germ cells that migrate to the developing gonads.

Question 81

Allantois functions?

Answer 81

small outer-pouching of the yolk sac that serves as an early site for blood formation and is associated with the development of the urinary bladder.

Question 82

What does the placenta contain?

Answer 82

embryonic/fetal portion formed by chorionic villi of the chorion and maternal portion formed by the endometrium

Question 82

What does the placenta contain?

Answer 82

embryonic/fetal portion formed by chorionic villi of the chorion and maternal portion formed by the endometrium

Question 83

What does the placenta supply?

Answer 83

The placenta mediates the exchange of material (nutrients, respiratory gases, metabolic wastes) between the embryonic/fetal and the mother’s circulatory systems. The placenta supplies oxygen and nutrients to the fetus from the maternal blood stream and excrete waste products from the fetus to the maternal blood stream. The placenta also helps to provide immune protection to the developing embryo/fetus. The placenta produces hormones (e.g. hCG, progesterone etc.) needed to sustain the pregnancy.

Question 83

What does the placenta supply?

Answer 83

The placenta mediates the exchange of material (nutrients, respiratory gases, metabolic wastes) between the embryonic/fetal and the mother’s circulatory systems. The placenta supplies oxygen and nutrients to the fetus from the maternal blood stream and excrete waste products from the fetus to the maternal blood stream. The placenta also helps to provide immune protection to the developing embryo/fetus. The placenta produces hormones (e.g. hCG, progesterone etc.) needed to sustain the pregnancy.

Question 84

Movement of blood through placenta?

Answer 84

Oxygen poor blood from the embryo/fetus travels to the placenta through the two arteries of the umbilical cord and passes through fingerlike projections (chorionic villi) of the placenta where oxygen and nutrients are acquired. Fetal blood (oxygen rich blood) leaves the placenta through the umbilical vein leading back to the embryo/fetus.

Question 85

What happens during the first trimester?

Answer 85

the implanted embryo secretes hormones to regulate the mother’s reproductive system and to indicate its presence. The hCG hormone secreted by the embryo, maintains the corpus luteum in the ovary to secrete progesterone and estrogen. Some amount of this hCG passes from the maternal blood to the urine. The presence of hCG in pregnant mother’s blood and urine can be easily detected and therefore is used as an early pregnancy detection test. High levels of progesterone brings about rapid changes in the mother. Both ovulation and menstrual cycles stop, the maternal side of the placenta grows, and the breasts and the uterus get larger. Mucus in the cervix of the mother forms a plug which prevents the fetus from infections. Most mothers experience nausea (morning sickness) during the first trimester.

Question 86

What happens during the second trimester?

Answer 86

By the second trimester, the level of hCG declines and as a result the corpus luteum deteriorates. But the placenta takes over the production of progesterone and estrogens which helps to maintain the pregnancy. Mother can feel fetal movements. As the fetus grows, mother’s abdominal organs become compressed and displaced.

Question 87

What happens during third trimester?

Answer 87

digestive blockage and frequent urination.

Question 88

What happens during fetal first trimester?

Answer 88

The first trimester is the most critical stage of development during which the rudiments of all major organ systems appear. This is the main period of organogenesis (the development of the body organs). The heart begins to beat by the 4th week (can be detected at 8-10 weeks). By the 8th week, embryo is said to be the fetus as all the parts of an adult are present in rudimentary form. At the end of the 1st trimester, the fetus is well differentiated and about 5 -7 cm long.

Question 89

fetal second trimester?

Answer 89

By the end of second trimester, the fetus assumes distinctively human features. Organ systems are completely developed in this stage. During the second trimester, the fetus grows to about 30 cm in length and is very active so that the mother may feel the fetal movements.

Question 90

fetal third trimester?

Answer 90

The third trimester represents a period of rapid fetal growth. During the early stage of this period, most of the organ systems become fully functional. During the third trimester, the fetus grows to about 50 cm in length and weighs about 3-4 kg. Fetal activity decrease as it fi lls the space within the uterus.

Question 91

Explain about maternal and fetal environmental tolerances?

Answer 91

During pregnancy the overall regulation of the mother’s immune system changes. These changes allow the mother to keep the embryo in her uterus without rejecting as a foreign body even though half the embryo’s genes are inherited from the father and many chemical markers on the surface of the embryo are foreign to the mother.

Question 92

What happens when the labor begins?

Answer 92

When labor begins, local regulators (prostaglandins) and hormones (mainly estradiol and oxytocin) induce and regulate further contractions of the uterus. This is a positive feedback mechanism as uterine contractions stimulate secretion of oxytocin which stimulates further contractions of the uterus.

Question 92

What happens when the labor begins?

Answer 92

When labor begins, local regulators (prostaglandins) and hormones (mainly estradiol and oxytocin) induce and regulate further contractions of the uterus. This is a positive feedback mechanism as uterine contractions stimulate secretion of oxytocin which stimulates further contractions of the uterus.

Question 93

What are the three stages of labour?

Answer 93

thinning and opening up (dilation) of the cervix. The second stage is the delivery of the baby. In this stage, continuous and strong contractions force the fetus out of the uterus and expell through the vagina. Delivery of the placenta is the final stage of labor.

Question 94

Main hormone in milk synthesis and secretion?

Answer 94

prolactin hormone

Question 95

What kind of regulation does lactation have?

Answer 95

nervous and hormonal regulation

Question 96

The main hormone in promoting milk synthesis and secretion

Answer 96

Prolactin

Question 97

What happens in response to suckling?

Answer 97

In response to suckling by the new born baby (which initiates nerve impulses from touch receptors in the nipples) and decrease in estradiol and progesterone levels in the mother’s blood after birth The hypothalamus send impulses to the anterior pituitary to secrete prolactin hormone which stimulates the mammary glands to produce milk.

Question 98

What does suckling also stimulate?

Answer 98

Suckling also stimulates the secretion of oxytocin hormone from the posterior pituitary gland and triggers the release (ejection) of milk from the mammary glands. This is a positive feedback mechanism as milk availability encourages continuous suckling, so touch sensation on the nipple and oxytocin release continue further ejecting milk from the mammary glands.

Question 99

What does colostrum contain?

Answer 99

sterile solution that contain nutrients such as lactose, fatty acids, amino acids, minerals, vitamins, and water that are ideal for baby’s digestion,

Question 100

Why is human milk important?

Answer 100

baby’s digestion, brain development and growth

Question 101

What does human milk have?

Answer 101

Human milk includes proteins such as casein, lactalbumin and immunoglobulins.

Question 102

Similarities of colostrum and true milk?

Answer 102

Colostrum and true milk provide nutrients for the baby and contain important antibodies that protect the infant. Several types of white blood cells are also present in the breast milk which help the baby to resist microbial infections.

Question 103

Difference between colostrum and true milk?

Answer 103

Compared to the true milk, colostrum contains less nutrients (less lactose and no fat) but they are adequate for the early nutritional needs.

Question 104

Difference between colostrum and true milk?

Answer 104

Compared to the true milk, colostrum contains less nutrients (less lactose and no fat) but they are adequate for the early nutritional needs.

Question 105

Breast feeding advantages?

Answer 105

Breast feeding supports optimal infant growth, enhances intellectual development and fosters mother-infant relations by establishing early and prolonged contact between them

Question 106

What are the deficiency symptoms of Vitamin A (retinol)?

Answer 106

Blindness, skin disorders, immunity impairment

Question 107

What are the main dietary sources of Vitamin A (retinol)?

Answer 107

Dark green vegetables, orange vegetables and fruits, dairy products

Question 108

Give another name for vitamin A

Answer 108

retinol

Question 109

What are the deficiency symptoms of Vitamin D?

Answer 109

Bone deformities(rickets) in children, bone softening in adults

Question 110

What are the dietary sources of Vitamin D?

Answer 110

Egg yolk, dairy products

Question 111

What are the dietary sources of Vitamin E?

Answer 111

Vegetable oils, nuts, seeds

Question 112

What are the deficiency symptoms of Vitamin E?

Answer 112

Nervous system degeneration

Question 113

What are the dietary sources of Vitamin K?

Answer 113

Green vegetables, tea, produced by colon bacteria

Question 114

What are the deficiency symptoms of Vitamin K?

Answer 114

Defective blood clotting

Question 115

What are fat soluble vitamins?

Answer 115

Vitamins A,D,K,E

Question 116

Give another name for Vitamin B1

Answer 116

Thiamine

Question 117

What are the dietary sources of Vitamin B1?

Answer 117

Legumes, peanuts, whole grains, pork

Question 118

What are the deficiency symptoms of Vitamin B1?

Answer 118

Beriberi(characterized by tingling, poor coordination, susceptibility to infection, reduced heart function)

Question 119

What are the dietary sources of Vitamin B2?

Answer 119

Dairy products, meats, vegetables, enriched grains

Question 120

What are the deficiency symptoms of Vitamin B2?

Answer 120

Skin lesions (cracks at corners of mouth)

Question 121

Give another name for Riboflavin

Answer 121

vitamin B2

Question 122

What are the deficiency symptoms of Vitamin B3?

Answer 122

Pellagra(characterized by lesions in skin, mental confusion and diarrhea)

Question 123

What are the dietary sources of Vitamin B3?

Answer 123

Grains, nuts, meats

Question 124

Give another name for Vitamin B3

Answer 124

Niacin

Question 125

What are the deficiency symptoms of Vitamin B5?

Answer 125

Fatigue, numbness, tingling of hands and feet

Question 126

What are the dietary sources of Vitamin B5?

Answer 126

Dairy products, fruits, vegetables, grains

Question 127

Give another name for Vitamin B5

Answer 127

Pantothenic acid

Question 128

Give another name for Vitamin B6

Answer 128

Pyridoxine

Question 129

What are the dietary sources of Vitamin B6?

Answer 129

Whole grains, Meats, vegetables

Question 130

What are the deficiency symptoms of Vitamin B6?

Answer 130

Irritability, anemia

Question 131

What are the dietary sources of Vitamin B7?

Answer 131

Meats, legumes, vegetables

Question 132

Give another name for Vitamin B7

Answer 132

Biotin

Question 133

What are the deficiency symptoms of Vitamin B7?

Answer 133

Neuro- muscular disorders, scaly skin infl ammation

Question 134

What are the dietary sources of Vitamin B9?

Answer 134

Green vegetables, whole grains

Question 135

What are the deficiency symptoms of Vitamin B9?

Answer 135

Anemia, birth defects

Question 136

Give another name for Vitamin B9

Answer 136

Folic Acid

Question 137

What are the deficiency symptoms of Vitamin B12?

Answer 137

Loss of balance, numbness, anemia

Question 138

What are the dietary sources of Vitamin B12?

Answer 138

Dairy products, eggs, meats

Question 139

Give another name for Vitamin B12

Answer 139

Cobalamin

Question 140

What are the dietary sources of Vitamin C?

Answer 140

Citrus fruits, broccoli, tomatoes

Question 141

What are the deficiency symptoms of Vitamin C?

Answer 141

Scurvy (characterized by degeneration of skin and teeth) , delayed wound healing

Question 142

Give another name for Vitamin C

Answer 142

Ascorbic Acid

Question 143

What are the dietary sources of Calcium

Answer 143

Dairy products, dark green vegetables, legumes

Question 144

What are the deficiency symptoms of Calcium

Answer 144

Loss of bone mass, impaired growth

Question 145

What are the dietary sources of Fe

Answer 145

Whole grains, green leafy vegetables, legumes, meats, eggs

Question 146

What are the deficiency symptoms of Fe

Answer 146

Anemia, weakness, impaired immunity

Question 147

What are the dietary sources of P

Answer 147

Rice, bread, milk, dairy products, fi sh, red meat

Question 148

What are the deficiency symptoms of P

Answer 148

Decaying of teeth and bones, weakness

Question 149

What are the deficiency symptoms of K?

Answer 149

Muscle weakness, nausea , paralysis, heart failure

Question 150

What are the dietary sources of K?

Answer 150

Fruits, vegetables, meat , dairy products, grains

Question 151

What are the dietary sources of I?

Answer 151

Sea foods , vegetables, iodized salt

Question 152

What are the deficiency symptoms of I?

Answer 152

Goiter( enlarged thyroid glands)

Question 153

What are the dietary sources of S?

Answer 153

Foods containing proteins

Question 154

What are the deficiency symptoms of S?

Answer 154

Fatigue, Impaired growth, swelling

Question 155

What are the dietary sources of Na and Cl?

Answer 155

Table salt

Question 156

What are the deficiency symptoms of Na and Cl?

Answer 156

Reduced appetite, muscle cramps

Question 157

What are the dietary sources of Mg?

Answer 157

Green leafy vegetables, grains

Question 158

What are the deficiency symptoms of Mg?

Answer 158

Disturbance in nervous system

Answer 159

Tea, sea food, drinking water

Question 160

What are the deficiency symptoms of F?

Answer 160

Tooth decay