Lecture 9

Question 1

Control of hormone secretion s usually part of which type of feedback loop?

Answer 1

Negative feedback loop.

Question 2

LSH and FSG are both released from the same signals.

Answer 2

Result depends on how the signal is received.

Question 3

In the ovaries, which product feeds back to shut off FSH?

Answer 3

Estradiol.

Question 4

PTH (parathyroid hormone).

Answer 4

Acts to increase blood calcium concentration. It stimulates osteoclasts in the bone to release more calcium from storage in bonds tissue, which increases blood calcium level.

Question 5

Lactation.

Answer 5

Requires a lot of calcium; the decrease in calcium is detected by PTH, which acts on the bone and causes release of calcium into the blood. The calcium is then used to make the milk.

Question 6

The pituitary gland is an important structure of the brain.

Answer 6

Infundibulum (stem-like stalk) connects the pituitary to the hypothalamus. Made up of 2 glands: anterior and posterior. It is also called the neurohypophysis.

Question 7

Anterior pituitary.

Answer 7

Synthesizes trophic hormones . Process: released from the hypothalamus through portal vessels and reaches the anterior pituitary gland.

Question 8

Growth hormone.

Answer 8

Causes uptake into bone.

Question 9

ACTH.

Answer 9

Targets the adrenal cortex, causes release of aldosterone (a mineralocorticoid) and retention of sodium, as well as potassium secretion.

Question 10

Gonadotropins (LH and FSH)/

Answer 10

They target the gonads; stimulate spermatogenesis and cause Leydig cells to secrete testosterone in males. In females, it stimulates the follicle: causes ovulation and formation of the corpus lute during pregnancy.

Question 11

Does the anterior pituitary produce hormones?

Answer 11

No; it just secretes them. Examples: oxytocin and ADH.

Question 12

Oxytocin.

Answer 12

Stimulates smooth muscle contractions.

Question 13

Adenphyphysis.

Answer 13

2 parts: pars anterior (major portion) and the pars intermedia. This tissue is composed of irregular clumps of secretory cells supported by 5 connective tissue fibres and surrounded by a rich vascular network.

Question 14

5 functional types of secretory cells in the adenophysos.

Answer 14

Somatotrophs (secrete GH- growth hormone, somatotropin), corticotrophs (secrete ACTH- adrenocorticotropic hormone and MSH- melanocyte stimulating hormone); Thyrotrophs (secrete TSH); lactotrophs (secrete PRL-prolactin); and gonadotropes (secrete LH and FSH).

Question 15

How does GH stimulate growth?

Answer 15

It stimulates the liver to produce growth factors, which in turn accelerate amino acid transport into cells; it is an anabolic type of hormone. It also stimulates lipid metabolism: accelerates mobilization of lipids from cells and speeds up lipid catabolism; this helps break down lipids to use them as a source of energy; hyperglycaemic effect.

Question 16

Insulin has opposite effects from GH.

Answer 16

Insulin from the pancreas promotes entry of glucose into the cells and promotes storage; GH stimulate triglyceride breakdown.

Question 17

Ways that GH affects metabolism.

Answer 17

promotes protein anabolism, promotes lipid mobilization and catabolism, indirectly inhibits glucose metabolism by shifting energy to lipid metabolism, and indirectly increases blood glucose.

Question 18

Adenohypophysis (anterior pituitary): prolactin (PRL).

Answer 18

Produced by lactotrophs in the anterior pituitary During pregnancy, PRL promotes development of the breasts, anticipating milk secretion. Oxytocin results in smooth muscle contractionL causes the milk to be ejected.

Question 19

Adenohypophysis (anterior pituitary): tropic hormones.

Answer 19

Tropic hormones stimulate the endocrine glands: TSH, ACTH, FSH, LH.

Question 20

Thyroid stimulating hormone (TSH).

Answer 20

Promotes and maintains growth and development of the thyroid, causes release of T3 and T4; regulates metabolism and calorigenic effect.

Question 21

Adrenocorticotropic hormone (ACTH).

Answer 21

Promotes and maintains normal growth and development of the cortex of the adrenal gland. Stimulates the adrenal cortex to secrete some of its hormones (cortisol and aldosterone).

Question 22

ACT promotes the secretion of which adrenal hormones?

Answer 22

Aldosterone and cortisol. Note: aldosterone can also be released in response to dehydration.

Question 23

Follicle-stimulating hormone (FSH).

Answer 23

In females: stimulates follicle growth and estrogen secretion. In males: stimulates development of testes and spermatogenesis in the Sertoli cells.

Question 24

Luteinizing hormone (LH).

Answer 24

In females: stimulates the formation and activity of corpus luteum of the ovary, triggering the release of progesterone and estrogen from the corpus luteum as well. LH also supports FSH in follicle maturation. In males: LH stimulates the Leydig cells in testes to develop and secrete testosterone.

Question 25

Name 2 gonadotropins.

Answer 25

FSH and LH.

Question 26

Through which feedback pathway does the hypothalamus adjust secretions of the anterior pituitary?

Answer 26

Negative feedback.

Question 27

FSH levels at menopause.

Answer 27

Levels rise.

Question 28

FSH on the ovary in normal circumstances.

Answer 28

FSH stimulates follicle growth. Follicle continues to grow, reaching a critical size as the level of estrogen increases. Estrogen then reaches a critical level, sending positive feedback through LH. LH release causes ovulation, which leads to formation of the corpus luteum; progesterone levels increase. If conception does not occur, the corpus luteum is destroyed, leading to a drop in progesterone.

Question 29

FSH levels on the ovary at menopause

Answer 29

Menopause: running out of oocytes (eggs). FSH tries to grow a follicle, but never gets the feedbackk inhibition from LH; FSH levels will rise a lot. There is no spike in estrogen, since there is no formation of the follicles. Body temperature fluctuates a lot. Homeostasis eventually forces this to shut down.

Question 30

How do hypothalamic regulatory hormones reach the anterior pituitary?

Answer 30

hypothalamic-hypophyseal portal system: direct connection to the hypothalamus.

Question 31

Corticotropin releasing hormone (CRH) and which hormone are released in conjunction from the anterior pituitary?

Answer 31

ACTH.

Question 32

Hypophyseal portal system.

Answer 32

An arrangement of blood vessels in which blood from one exiting tissue is immediately carried to a second tissue before returning to the heart.

Question 33

Hormones released from the hypothalamus to the anterior pituitary in the hypophyseal portal system.

Answer 33

Growth hormone releasing hormone (GHRH), growth hormone inhibiting hormone (GHIH), corticotropin releasing hormone (CRH), thyrotropin releasing hormone (TRH), gonadotropin releasing hormone (GnRH), prolactin releasing hormone (PRH), and prolactin inhibiting hormone (PIH).

Question 34

Hypothalamus and the posterior pituitary,

Answer 34

Neurosecretory cells have their bodies in the hypothalamus and their axon terminals in the posterior pituitary, They do not produce the hormones, merely secrete them,

Question 35

Does the posterior pituitary make hormones?

Answer 35

No, it simply secretes them.

Question 36

3 methods of hormone pathology.

Answer 36

Hormone excess, hormone deficiency, and abnormal responsiveness of target tissues.

Question 37

Hormone excess: Cushing’s disease.

Answer 37

Excessive amounts of cortisol. Normal cortisol action: protein breakdown, glucose formation, lipolysis, anti-inflammatory effect, and depression of immune response. Hypersecretion of cortisol: a tumour of the adrenal gland secretes an excess of ACTH, which stimulates excessive secretion of cortisol. There is a breakdown of muscle proteins and redistribution of fat, resulting in “moon face:, pendulous abdomen, and flushed appearance.

Question 38

Hormone deficiency: underachieve thyroid.

Answer 38

Normal actions of thyroid hormones: increase BMR, stimulate use of oxygen to make ATP, calorigenic effect, stimulates protein synthesis and increased use of glucose and fatty acids for ATP production, enhances the actions of catecholamines (epinephrine and norepinephrine), and accelerates body growth,. Deficiency: swelling of facial tissue (puffiness), slow heart rate, low body temperature, sensitivity to cold, dry hair and skin. It can lead to iodine deficiency, stress, and congenital.

Question 39

Abnormal responsiveness of target tissueL Type 2 diabetes,

Answer 39

Normal action of insulin: accelerates facilitated diffusion of glucose into cells, speeds up conversion of glucose into glycogen, increases uptake of amino acids, increases protein synthesis, lipogenesis, slows glycogenolysis, and slows gluconeogenesis. Abnormal response causes high blood glucose weight loss, excessive e thirst, and frequent urination.

Question 40

Type I diabetes.

Answer 40

Production of insulin is inhibited.

Question 41

Type II diabetes.

Answer 41

Insulin is present in large amounts, but cells are not responding to it.

Question 42

Which components balance calcium ion use?

Answer 42

Calcitonin, parathyroid hormone, and vitamin D.