Chapter 23 Endocrine Control of Growth

Question 1

What are the steps in Cortisol synthesis?

Answer 1

hypothalamus –CRH–> anterior pituitary –ACTH–> adrenal cortex—–> cortisol

Question 2

What does cortisol do to the immune system?

Answer 2

suppresses immune function

Question 3

What does cortisol do to the liver?

Answer 3

gluconeogenesis

Question 4

What does cortisol do to muscles?

Answer 4

protein catabolism

Question 5

what does cortisol do to adipose tissue?

Answer 5

lipolysis

Question 6

What stimulates cortisol synthesis?

Answer 6

ACTH

Question 7

How is cortisol transported?

Answer 7

transported in the plasma to target cell which it diffuses into cells and binds to intracellular receptors that enter the nucleus and binds to DNA.

Question 8

What does cortisol control?

Answer 8

gene expression

Question 9

How does cortisol protect against hypoglycemia?

Answer 9

by promoting gluconeogenesis, breaking down skeletal muscle protein, enhancing lipolysis, suppressing immune function, causing calcium and bone matrix loss, causing mood changes and alters learning & memory.

Question 10

What disease are associated with hypercortisolism?

Answer 10

Chushing’s syndrome (caused by pituitary tumor increasing ACTH)

(2ndary hypercortisolism)

Question 11

What disease is associated with hypocorticolism?

Answer 11

Addison’s disease (caused by autoimmune disease of the adrenal cortex)

Question 12

What is POMC and what does it produce?

Answer 12

a prohormone that produces ACTH & a-MSH

Question 13

What does the hormone a-MSH (melanocyte-stimulating hormone) do?

Answer 13

Melanin synthesis, immune response and decrease food intake

Question 14

Which melanocortin receptor is found in skin melanocytes and causes skin darkening?

Answer 14

MC1

Question 15

Which melanocortin receptor is found in the adrenal cortex and stimulate cortisol secretion?

Answer 15

MC2

Question 16

Which melanocortin receptor is found in the hypothalamus and inhibits feeding?

Answer 16

MC4

Question 17

Which melanocortin receptor(s) respond to BOTH ACTH and MSH?

Answer 17

MC1 & MC4

Question 18

Which melanocortin receptor only responds to ACTH and not MSH?

Answer 18

MC2

Question 19

Which hormone(s) increase feeding?

Answer 19

ghrelin—–> neuropeptide Y

Question 20

What hormone(s) decrease feeding?

Answer 20

a-MSH & Leptin

Question 21

What are the 6 steps involved in the synthesis of thyroid hormones (T3, T4)?

Answer 21

1. Na+/I- symporter brings I- into the cell, then the Pendrin transporter moves I- into the colloid
2. Follicular cell synthesizes enzymes & thyroglobulin for colloid
3. Thyroid peroxidase adds I- to tyrosine making T3 & T4
4. Thyroglobulin containing T3 & T4 is transported back into the follicular cell in vesicles
5. Intracellular enzymes separate T3 & T4 from the protein
6. Free T3 & T4 enter circulation

Question 22

How are thyroid hormones transported to target cells?

Answer 22

Thyroid hormones are hydrophobic transported in the plasma bound to globulin (not thyroglobulin) and bind to intracellular receptors in the nucleus to regulate gene expression

Question 23

What do thyroid hormones do in adults?

Answer 23

Increase oxygen consumption, generate heat and alter ion transport across cell and mitochondrial membranes

Question 24

What do thyroid hormone do in children?

Answer 24

facilitate growth hormone action, promote myelin and synapse formation

(thyroid hormones in children are needed for normal growth and development)

Question 25

What are consequences of hyperthyroidism?

Answer 25

increased oxygen consumption & heat production, protein breakdown & muscle weakness, rapid heartbeat and psychological effects

Question 26

What are consequences of hypothyroidism?

Answer 26

Slower oxygen consumption & intolerance of cold, decreased protein synthesis, slowed reflexes, speech & thought and slow heart rate (bradycardia)

Question 27

What are the steps in control of thyroid hormone release?

Answer 27

hypothalamus--TRH--> anterior pit.--TSH--> thyroid gland-------->T3 & T4

Question 28

What are the steps in the release of Growth Hormones?

Answer 28

circadian rhythm, stress & cortisol, and fasting----------------------> hypothalamus--GHRH--> anterior pit.--GH--> liver--IGF----> cartilage growth

Question 29

What hormones inhibit GH?

Answer 29

somatostatin & IGF (insulin-like growth factors)

Question 30

What are function of GH?

Answer 30

stimulates bone & tissue growth and increases blood glucose

Question 31

What is the function of the hormone IGF?

Answer 31

Cartilage growth

Question 32

What is the function of GH in children?

Answer 32

influences bone growth

Question 33

What will excess GH and GH deficiency cause in children?

Answer 33

excess GH--> gigantism GH deficiency---> dwarfism

Question 34

What does excess GH in adults cause?

Answer 34

acromegaly

Question 35

What is the function of GH in adults?

Answer 35

acts on cartilage & soft tissue

Question 36

Where in the bone does bone growth occur?

Answer 36

epiphyseal plate

Question 37

When does bone growth stop?

Answer 37

sex hormones lead to inactivation of the epiphyseal plate following puberty

Question 38

What produced bone cartilage?

Answer 38

chondrocytes

Question 39

What is laid down on the collagen matrix?

Answer 39

calcium phosphate (hydroxyapatite)

Question 40

What is cartilage made of?

Answer 40

collagen & proteoglycan

Question 41

Where is calcium taken up, eliminated and stored in?

Answer 41

taken up by intestine eliminated by kidneys stored in bone

Question 42

What are the roles of PTH, calcitriol, cortisol and calcitonin in bones?

Answer 42

PTH, calcitriol & cortisol release calcium from bone (osteoclastic activity) Calcitonin = osteoblast activity (building bone)

Question 43

What is released when blood calcium levels are low?

Answer 43

PTH--Ca2+---> Kidney---calcitriol---> increases Ca2+ in distal nephron & intestine

Question 44

What is the 0.1% Ca2+ in the ECF essential for?

Answer 44

second messanger, tight junction integrity, blood coagulation and neuron polarization

Question 45

PTH stimulated calcitriol production in the _________.

Answer 45

kidney

Question 46

Which hormones are peptide hormones?

Answer 46

GH, calcitonin, PTH and IGF (insulin-like growth factor)

Question 47

Which hormones are steroid hormones?

Answer 47

cortisol, aldosterone, TH, and calcitriol (D3)

Question 48

What is bone reabsorption mediated by?

Answer 48

Osteoclasts

Question 49

What is bone deposition mediated by?

Answer 49

Osteoblasts