Chapter 5.2

Question 1

How does the hypothalamus control the pituitary gland

Answer 1

• it controls the pituitary gland through paracrine release of hormones into a portal system
• > this portal system directly connects the two organs

Question 2

How is the release of hormones regulated by the hypothalamus

Answer 2

-it is regulated by negative feedback

Question 3

What blood vessel system connects the anterior pituitary with the hypothalamus

Answer 3

• the hypophyseal portal system is a blood vessel system

- >that connects the hypothalamus to the anterior pituitary

Question 4

List the hormones released by the anterior pituitary. There are 7.

Answer 4

1) ACTH
2) TSH
3) LH
4) FSH
5) Prolactin
6) Endorphins
7) Growth Hormone

Question 5

List the hormones released by the hypothalamus. There are 4.

Answer 5

1) CRF
2) TRH
3) GnRH
4) PIF(prolactin inhibiting factor)->actually dopamine
5) GHRH

Question 6

How does the hypothalamus communicate with the posterior pituitary gland

Answer 6

-posterior pituitary does not receive TROPIC hormones
through the hypophyseal system
->rather hypothalamus sends axons down the PITUITARY STALK directly onto the posterior pituitary

Question 7

What two hormones are released by the posterior pituitary

Answer 7

• oxytocin
• > increases uterine contractions during labour
• > also increases milk letdown during lactation
• ADH
• > increases reabsorption of water in the collecting ducts of the kidney
• > it is released in response to increased plasma osmolarity or increased concentration of solutes within the blood

Question 8

What are the four tropic hormones released by the anterior pituitary

Answer 8

1) FSH
2) LH
3) TSH
4) ACTH

Question 9

What are the three direct hormones released by the posterior pituitary

Answer 9

1) Prolactin
- >stimulates milk production in mammary glands
- >blocked in release until placenta is removed
- >in this case, progesterone/estrogen/dopamine levels drop

2) Growth hormone
3) Endorphins

Question 10

What is the mechanism of growth hormone

Answer 10

• prevents glucose uptake in certain tissues(those that are not growing)
• stimulates the breakdown of fatty acids

Question 11

What is the result of too much or too little GH during childhood

Answer 11

Too much= gigantism

Too little= dwarfism

Question 12

What does excess GH in adult stage result in

Answer 12

-results in acromegaly

Question 13

Describe again how ADH works

Answer 13

• increased blood osmolarity(sensed by osmoreceptors)
• decrease blood volume(sensed by baroreceptors)

-mechanism occurs in the collecting duct

Question 14

What kind of loop does oxytocin work off. Note that oxytocin can be released due to suckling on the nipple by infants

Answer 14

• it works off a positive feedback loop
• > release promotes uterine contractions
• > which promotes more oxytocin release

Question 15

What are the two major functions of the thyroid hormone

Answer 15

-setting basal metabolic rate and calcium homeostasis

• metabolic rate is controlled by T3/T4
• calcium levels are controlled by calcitonin

Question 16

How are T3 and t4 produced in the thyroid

Answer 16

-by the iodination of the amino acid tyrosine in the follicular cells of the thyroid

Question 17

What does increased levels of T3 and T4 do. Note that it has to do with cellular respiration

Answer 17

• increased levels of T3/T4= increased cellular respiration

- >therefore, greater amount of protein and fatty acid turnover

Question 18

What condition does a deficiency in iodine lead to

Answer 18

• it results in hypothyroidism

- >characterized by lethargy, decreased body temperature, slow respiratory/heart rate, cold intolerance and weight gain

Question 19

What condition does an excess stimulation in iodine lead to

Answer 19

• it results in hyperthyroidism

- >increased body temperature, increased respiration, heart rate and weight loss(also heat intolerance)

Question 20

What cells produce calcitonin? What is the role of calcitonin?(describe the three ways it reduces calcitonin)

Answer 20

• C cells produce calcitonin
• calcitonin acts to decrease plasma calcium levels in three ways
• > increased calcium excretion from the kidneys
• > decreased calcium absorption from the gut
• > increased storage of calcium in the bone

Question 21

What stimulates the secretion of calcitonin from the C-cells

Answer 21

-high levels of calcium in the blood stimulate secretion of calcitonin from the C-cells

Question 22

What is the role of PTH?

Answer 22

• antagonistic hormone to calcitonin
• it decreases the excretion of calcium by the kidneys
• increases absorption of calcium in the gut
• increases bone resorption

Question 23

How are PTH and Vitamin D related

Answer 23

• PTH activates vitamin D

- >which is required for the absorption of calcium and phosphate in the gut

Question 24

Does PTH have an effect on phosphate levels

Answer 24

• no

- >it just increases calcium levels

Question 25

What are the role of glucocorticoids? Give two examples

Answer 25

- they are hormones that regulate glucose levels - >they also affect protein metabolism - >examples are: cortisol and cortisone

Question 26

How do glucocorticoids relate to protein synthesis and gluconeogenesis

Answer 26

-they increase gluconeogenesis and decrease protein synthesis

Question 27

How does glucocorticoids related to inflammation and immunological responses

Answer 27

-they decrease inflammation and immunologic responses

Question 28

What are the roles of mineralcorticoids. Give an example of this type of hormone.

Answer 28

- used in salt and water homeostasis - >their most profound effect are on the kidneys - an example is aldosterone - >increases sodium reabsorption in the distal convoluted tubule and the collecting duct of the nephron

Question 29

How does aldosterone work in terms of blood pressure and plasma osmolarity? Also describe its relation to potassium and hydrogen ions.

Answer 29

- it increases blood pressure but does not affect plasma osmolarity - it decreases the reabsorption of potassium and hydrogen ions in distal/collecting duct - >promoting their excretion in urine

Question 30

Where are angiotensin-converting enzymes located

Answer 30

-they are located in the lungs

Question 31

Name the three corticosteroids

Answer 31

1) Glucocorticoids(sugar) 2) Mineralcorticoids(salt) 3) Cortical sex hormones(sex)

Question 32

What is the role of glucagon? What cells is it produced by? When is it inhibited?

Answer 32

- it is produced by alpha cells - it is secreted during times of fasting - >when glucose levels run low - >glucagon is released to convert glycogen to glucose - >also increases gluconeogenesis -it is inhibited when glucose levels are high

Question 33

What is the role of insulin? What cells is it produced by? When is it inhibited?

Answer 33

- the role of insulin is antagonistic to glucagon - it is secreted when blood glucose levels are high - >secreted by beta cells -it stimulates anabolic processes like fat and protein synthesis

Question 34

What is aldestorone under the control of

Answer 34

- under the control of renin-angiotensin-aldosterone system - >decreased blood pressure causes juxtaglomerular cells of the kidney to secrete renin - >renin cleaves inactive plasma protein, angiotensionegen, to its active form, angiotensin 1 - >angiotensin 1 is converted to angiotensin 2 by angiotensin converting enzyme - >angiotensin 2 stimulates the adrenal cortex to secrete aldosterone

Question 35

Is the pancreas an exocrine and endocrine tissue

Answer 35

- yes - >the exocrine tissue secrete substance directly into the ducts - >the endocrine aspect there are hormone-producing cells grouped together into islets of Langerhans - islets contain alpha, beta and delta cells - >alpha cells secrete glucagon, beta cells secrete insulin and delta cells secrete somatostatin

Question 36

What does underproduction of insulin lead to

Answer 36

- diabetes mellitus - >characterized by hyperglycemia - >glucose can result in urine - >this can lead to excess excretion of water and an increase in urine volume

Question 37

Do diabetics often report polyruia(increased frequency of urination) and polydipsia(increased thirst)

Answer 37

-yes

Question 38

What are the two types of diabetes

Answer 38

Type 1 - >insulin dependant diabetes - >caused by autoimmune destruction of the beta cells of the pancreas - >these individuals produce little or no insulin because the majority of the beta cells are destroyed Type 2 - >this is non insulin dependant diabetes - >result of receptor level resistance to the effects of insulin - >due to diet and obesity

Question 39

What is somatostatin and how is it released

Answer 39

- it is an inhibitor of insulin and glucagon - >high blood glucose and amino acid concentrations stimulate its secretion -somatostatin can also decrease grwoth hormone secretion

Question 40

How does the pineal gland know when to release melatonin

Answer 40

-because of its projections directly from the retina

Question 41

Discuss erythripoietin, ANP, and thymosin

Answer 41

Erythripoietin - >produced by the kidneys - >stimulates red blood cell production in the bone marrow Heart - >releases ANP to help regulate salt and water balance - >when cells in the atria are stretched from excess blood volume, they release ANP - >this hormone promotes excretion of sodium and increases urine volume - >lowers blood volume and pressure and has no effect on blood osmolarity Thymosin - >located behind the sternum - >important for proper T-cell development and differentiation