Endocrine - Hypothalamus and Pituitary Glands

Question 1

What does the Hypothalamus Secrete?

Answer 1

Dopamine
TRH
CRH
GnRH
GHRH
SS

Question 2

Where is the hypothalamus?

Answer 2

Above the pituitary gland
Neural Tissue

Question 3

What is the function of the hypothalamus?

Answer 3

Integrates sensory stimuli about heat, light, and BP, etc.
Communicates with pituitary to direct physiological responses
Releasing hormones secreted into a portal capillary bed stimulate cells the anterior pituitary gland

Question 4

Define

Supraoptic nuclei (SON) and Paraventricular nuclei (PVN)

What are they? Where are they?

Answer 4

Collections of neurons that project to the posterior pituitary gland (neural communication)

Question 5

Tumors in the anteror pituitary can cause vision loss due to…

Answer 5

compression of the optic chiasm

Question 6

What is the function of the Posterior Pituitary Gland?

Answer 6

Extension of the hypothalamus
Hormones synthesized in hypothalamus travel through axons to the posterior pituitary gland
APs stimulate release of hormones from posterior pituitary

Question 7

What happens once hormone release is stimulated in posterior pituitary?

Answer 7

APs stimulate the release of hormones from the posterior pituitary gland into the vascular capillary bed
Hormones travel through the bloodstream to target organs

Question 8

Define

Magnocellular

Answer 8

Cell bodies found in the hypothalamus synthesize hormones

Question 9

What hormones are released from the Posterior Pituitary?

Answer 9

Oxytocin
ADH

Question 10

What is the function of Oxytocin?

Answer 10

Uterine muscle contraction during birth and contraction of myoepithelial cells in breath

Question 11

Why is oxytocin released?

Answer 11

Birth - in response to cervical stretch
Suckling of nipple for milk

Question 12

What is the function of ADH?

Answer 12

Water reabsorption in the kidney to ↑ water in plasma → ↑ BP, ↓water in urine

Question 13

What kind of feedback loop is the release of oxytocin?

Answer 13

Positive

Question 14

Why is ADH released?

Answer 14

↓BP
↑Plasma osmolarity
Dehydration

Question 15

Parvocellular Neurons

Answer 15

In the hypothalamus
Secrete releasing hormones into the hypothalamohypopyseal portal vessels

Question 16

What is the function of the Anterior Pituitary?

Answer 16

Releasing hormones secreted into the hypothalamohypopyseal portal vessels stimulate anterior pituitary cells to release different tropic hormones into the bloodstream that travel to target organs to stimulate secretion of other hormones

Question 17

What does the Anterior Pituitary Gland secrete?

Answer 17

FSH
LH
ACTH
TSH
Prolactin
I (Ignore)
GH

FLAT PIG

Question 18

What needs to happen to hormones released from the anterior pituitary because they are peptide/protein hormones?

Answer 18

They need to bind to receptors located in the cell membrane of target cells
They will also elicit responses quickly in target cells (often stimulating release of hormone containing vesicles)

Question 19

What is unique about GH and Prolactin?

Answer 19

Both have negative inhibitors
↓ negative regulator → remove inhibition → ↑ prolactin or GH

Question 20

Gonadotrope produces _ and stimulates _

Answer 20

FSH or LH
Gonads

Question 21

Thyrotrope produces _ and stimulates _

Answer 21

TSH
Thyroid Gland

Question 22

Corticotrope produces _ and stimulates _

Answer 22

ACTH
Adrenal cortex

Question 23

Lactotrope produces _ and stimulates _

Answer 23

Prolactin
Mammary Gland

Question 24

Somatotrope produces _ and stimulates _

Answer 24

GH
Somatic Cells (to grow)

Question 25

# Hypothalamic pathway of dopamine The hypothalamus secretes dopamine which...

Answer 25

Inhibits the release of prolactin from the anterior pituitary gland Prolactin will stimulate the breast to produce milk ↑ Dopamine → ↓prolactin seceion and milk production

Question 26

# Hypothalamic pathway of TRH The hypothalamus secretes TRH which...

Answer 26

stimulates the anterior pituitary gland to secrete TSH. TSH stimulates the thyroid gland to release T3 and T4. T3 and T4 impact many tissues | The thyoid axis

Question 27

# Hypothalamic pathway of CRH The hypothalamus releases CRH which...

Answer 27

will stimulate the anterior pituitary gland to secrete ACTH ACTH travels to the adrenal cortex where cortisol is released Cortisol impacts many tissues | Adrenal Axis

Question 28

# Hypothalamic pathway of Somatostatin The hypothalamus secretes Somatostatin which...

Answer 28

inhibits GH release from the anterior pituitary gland. GH will stimulate the liver to secrete IGF-1. ↑ somatostatin → ↓GH and IGF-1

Question 29

# Hypothalamic pathway of GHRH The hypothalamus secretes GHRH which...

Answer 29

stimulates GH release from the anterior pituitary gland. GH will stimulate the liver to secrete IGF-1 GH and IGF-1 impact many tissues | Growth Axis

Question 30

# Hypothalamic pathway of GnRH The hypothalamus secretes GnRH which...

Answer 30

will stimulate the anterior pituitary gland to secrete oth FSH and LH. FSH and LH will stimulate the testes and ovaries to release androgens, estrogens, and progesterone. Androgens, estrogens, and progesterone impact many tissues | Gonadal axis

Question 31

What is the function of tropic cells?

Answer 31

Stimulate other cells

Question 32

Basic Growth Hormone Axis

Answer 32

Hypothalamus → secretes GHRH → stimulates Anterior Pituitary → secretes GH → stimulates Liver/Bone → secretes IGF-1 → IGF-1 travels through the blood → stimulates SSTN → inhibits GH secretion from AP

Question 33

# Define Anabolic

Answer 33

Builds up

Question 34

# Define Catabolic

Answer 34

Break down

Question 35

How can GH promote both anabolic and catabolic processes?

Answer 35

GH is anabolic in fed state (caloric excess) GH is catabolic in fasted state

Question 36

What are the effects of GH and IGF-1 when GH is in the fed state (anabolic) on the liver?

Answer 36

GH stimulates liver → ↑ RNA synthesis, Protein Synthesis, IGFBP, IGFs → stimulates release of IGF-1

Question 37

What are the effects of GH and IGF-1 when GH is in the fed state (anabolic) on bone, heart, and lung?

Answer 37

GH and IGF-1 stimulate Bone, heart, lung → ↑Protein/DNA/RNA Synthesis, Cell size and number (**↑Organ size and function**)

Question 38

What are the effects of GH and IGF-1 when GH is in the fed state (anabolic) on muscle?

Answer 38

GH and IGF-1 stimulate Muscle → ↑Amino Acid uptake, Protein Synthesis (↑Lean body mass)

Question 39

What are the effects of GH and IGF-1 when GH is in the fed state (anabolic) on chondrocytes in bone?

Answer 39

GH and IGF-1 stimulate chondrocytes in bone → ↑Amino Acid uptake, ↑Protein/DNA/RNA Synthesis, ↑Collagen, ↑Chondroitin sulfate, ↑Cell size and number (↑Linear Growth)

Question 40

What organs/glands/cells do GH and IGF-1 stimulate when GH is in the fed state (anabolic)?

Answer 40

Kidney Pancreas Intestine Islet cells Parathyroid Skin Connective Tissue

Question 41

When GH is in the fasted state (catabolic), what effect does it have on adipose tissue?

Answer 41

GH stimulates adipose tissue → ↓Glucose uptake, ↑Lipolysis; **↓Adiposy**

Question 42

When GH is in the fasted state (catabolic), what effect does it have on the liver?

Answer 42

GH stimulates Liver → ↑Gluconeogenesis → stimulates IGF-1 release → ↑Organ size/function, ↑Linear growth, ↑Lean body mass

Question 43

When GH is in the fasted state (catabolic), what effect does it have on the muscle?

Answer 43

GH stimulates Muscle → ↓Glucose uptake → ↑Lean body mass

Question 44

What is the effect of loss of GH during normal aging? What does it result in?

Answer 44

loss of GH during normal aging → ↓ lean muscle mass, ↑ fat mass, ↓ bone density Causes: frality, muscle atrophy, relative obesity, ↑frequency of fractures and disordered sleep (old age)

Question 45

How does GH secretion change throughout life?

Answer 45

GH rises after birth; higher [] than adults → levels out in childhood → Peaks during puberty → ↓ between puberty and adult life → stabilizes during adult life → declines in old age

Question 46

# GH Pathologies, disruption of homeostasis GH oversecretion **before** puberty = | What does it cause?

Answer 46

Tall stature

Question 47

# GH Pathologies, disruption of homeostasis GH oversecretion after puberty = | What does it call?

Answer 47

Acromegaly | ↑Bone width

Question 48

# GH Pathologies, disruption of homeostasis GH undersecretion = | What does it cause?

Answer 48

Short stature

Question 49

# GH Pathologies, disruption of homeostasis GH receptor deficiency = | What does it cause?

Answer 49

Short stature (Laron Dwarfism)

Question 50

# Feedback Loops What would you expect the concentration of GHRH, GH, IGF-1, and Somatostatin in someone with **acromegaly** relative to a "normal" patient? What would you expect for blood glucose, amino acids, and free fatty acids?

Answer 50

Low GHRH High GH High IGF-1 High Somatostatin High Blood Glucose Low Amino Acids High Free Fatty Acids

Question 51

# Feedback Loops What would you expect the concentration of GHRH, GH, IGF-1, and Somatostatin in someone with **growth hormone deficiency** relative to a "normal" patient? What would you expect for blood glucose, amino acids, and free fatty acids?

Answer 51

High GHRH Low GH Low IGF-1 Low Somatostatin Low Blood Glucose High Amino Acids Low Free Fatty Acids

Question 52

# Feedback Loops What would you expect the concentration of GHRH, GH, IGF-1, and Somatostatin in someone with **growth hormone receptor deficiency** relative to a "normal" patient? What would you expect for blood glucose, amino acids, and free fatty acids?

Answer 52

High GHRH High GH Low IGF-1 Low Somatostatin Low Blood Glucose High Amino Acids Low Free Fatty Acids

Question 53

Why is GHRH low in a patient with **acromegaly** relative to a normal patient?

Answer 53

GH feeds back to inhibit GHRH secretion

Question 54

Why are blood free fatty acids high in a patient with **acromegaly** relative to a normal patient?

Answer 54

GH promotes lipolysis in adipose tissue, therby increasing fatty acids in blood

Question 55

Why is IGF-1 high in a patient with **acromegaly** relative to a normal patient?

Answer 55

GH stimulates excess IGF-1 secretion

Question 56

Why is Somatostatin high in a patientn with **acromegaly** relative to a normal patient?

Answer 56

excess GH triggers this inhibitor

Question 57

Why is Blood Glucose high in a patient with **acromegaly** relative to a normal patient?

Answer 57

GH prevents insulin induced uptake of glucose

Question 58

Why are Blood amino acids low in a patient with **acromegaly** relative to a normal patient?

Answer 58

GH promotes amino acid uptake into muscle

Question 59

Why is GHRH high in a patient with **GH Receptor Deficiency** relative to a normal patient?

Answer 59

GH receptors are defective so the hypothalamus is not able to sense the high levels of GH

Question 60

Why is IGF-1 low in a patient with **GH Receptor Deficiency** relative to a normal patient?

Answer 60

GH receptors are defective,so GH is unable to stimulate iGF-1 release

Question 61

Why is Somatostatin low in a patient with **GH Receptor Deficiency** relative to a normal patient?

Answer 61

lack of GH activity leads to low SS

Question 62

Why is Blood Glucose low in a patient with **GH Receptor Deficiency** relative to a normal patient?

Answer 62

GH is unable to prevent uptake into skeletal muscle and adipose, so glucose gets into muscle/adipose and leaves blood

Question 63

Why are Blood amino acids high in a patient with **GH Receptor Deficiency** relative to a normal patient?

Answer 63

GH receptor defect prevents the muscle from taking up amino acids in the blood, leading to muscle mass

Question 64

Why are Blood Free Fatty Acids low in a patient with **GH Receptor Deficiency** relative to a normal patient?

Answer 64

GH receptor defect reduces lipolysis in the adipose tissue, thus adipose tissue remains full of fat substrates