Hypothalamus and Anterior/Posterior Pituitary

Question 1

What does the hypothalamic-pituitary relationship regulate?

Answer 1

thyroid gland
adrenal glands
reproductive glands
growth
milk production
ejection
osmoregulation

Question 2

How does the hypothalamus control the posterior pituitary?

Answer 2

neural control

Question 3

How does the hypothalamus control the anterior pituitary?

Answer 3

neural and endocrine control

Question 4

What is the predominant hormone secreted by the pars intermedia?

Answer 4

melanocyte stimulating hormone (MSH)

Question 5

Briefly describe equine Cushing’s disease

Answer 5

caused by hypothalamic neuron degeneration
results in hypertrophy, hyperplasia, and adenoma formation in pars intermedia
excess POMC produced

Question 6

Name the 6 hypothalamic hormones

Answer 6

growth hormone releasing hormone (GHRH)
somatostatin (SS)
thyroid releasing hormone (TRH)
corticotropin releasing hormone (CRH)
prolactin inhibiting hormone (PIH)
gonadotropin releasing hormone (GnRH)

Question 7

Name the 6 anterior pituitary hormones

Answer 7

FSH
LH
TSH
ACTH
GH
prolactin

Question 8

Characteristics of glycoprotein hormone family

Answer 8

consists of TSH, LH, FSH
two subunits
beta subunit confers biological specificity

Question 9

Functions of LH

Answer 9

stimulates secretion of sex steroids from the gonads

also causes ovulation if large burst released

Question 10

Functions of TSH

Answer 10

stimulates thyroid hormone synthesis and secretion
promotes thyrocyte growth
increases intrathyroidal deiodination of T4 to T3
initiates uptake of iodide from the blood by the thyroid gland

Question 11

Cause of primary hypothyroidism

Answer 11

thyroid dysfunction

Question 12

Cause of secondary hypothyroidism

Answer 12

anterior pituitary dysfunction

Question 13

Cause of tertiary hypothyroidism

Answer 13

hypothalamus dysfunction

Question 14

Functions of ACTH

Answer 14

stimulates the adrenal gland to release cortisol

Question 15

Functions of GH

Answer 15

stimulates target cell growth and division
increases rate at which cells utilize protein
causes fat break down and use for energy
development of muscles and bones

Question 16

What stimulates growth hormone?

Answer 16

decreased glucose
decreased free fatty acids
arginine
fasting/starvation
puberty hormones
exercise
stress
sleep

Question 17

What inhibits growth hormone?

Answer 17

increased glucose
increased free fatty acids
obesity
senescence
somatostatin
somatomedins
GH
pregnancy

Question 18

Diabetogenic effect of GH

Answer 18

causes insulin resistance
decreases glucose uptake and utilization by muscle and adipose tissue
increases lipolysis in adipose tissue
increases blood insulin levels

Question 19

Pathyophysiology of excess GH

Answer 19

acromegaly!
weight gain
extremity enlargement
growth of paws, chin, skull

Question 20

Feline acromegaly

Answer 20

GH causes increased glucose, which causes increased insulin

high insulin levels cause downregulation of insulin receptors on target tissues (resulting in CHO intolerance)

Question 21

Pathophysiology of pituitary dwarfism

Answer 21

shortened life span
permanent dentition is delayed or absent
bilateral symmetrical alopecia
secondary hypothyroidism and hypoadrenocorticism
external genitalia remain infantile

Question 22

Characteristics of prolactin

Answer 22

influences parenting behaviors
suppresses lipid storage
growth support of pancreatic islets
stimulates insulin
marked effects on immune function

Question 23

What is the primary stimulating hormone of prolactin?

Answer 23

TRH

Question 24

What is the main inhibiting factor of prolactin?

Answer 24

dopamine

Question 25

Where does dopamine come from? (3)

Answer 25

1. dopaminergic neurons in hypothalamus 2. dopaminergic neurons in the posterior pituitary that connect via short portal veins 3. non-lactotroph cells of the anterior pituitary

Question 26

What are the 2 hormones secreted by the posterior pituitary?

Answer 26

``` antidiuretic hormone (ADH)/vasopressin oxytocin ```

Question 27

What is the major physiological effect of ADH?

Answer 27

conservation of body water (by acting on kidney)

Question 28

What is the major physiological effect of oxytocin

Answer 28

stimulates milk ejection and uterine contractions

Question 29

Function of ADH

Answer 29

binds to receptors in distal or collecting tubules of kidney | promotes reabsorption of water back into circulation

Question 30

How does ADH stimulate water reabsorption?

Answer 30

by stimulating insertion of aquaporins into membranes of kidney tubules

Question 31

What is the main variable that regulates ADH?

Answer 31

plasma osmolarity (solute concentration)

Question 32

Factors that stimulate ADH

Answer 32

``` increased serum osmolarity decreased extracellular fluid angiotensin 2 pain nausea hypoglycemia nicotine opiates ```

Question 33

Factors that inhibit ADH

Answer 33

``` decreased serum osmolarity hypervolemia ethanol alpha adrenergic agonists ANP ```

Question 34

What is diabetes insipidus?

Answer 34

deficiency in ADH secretion | results in large amounts of dilute urine and body fluids become concentrated

Question 35

What is nephrogenic diabetes insipidus?

Answer 35

kidney is unable to respond to ADH even though ADH concentrations are high

Question 36

What can stimulate oxytocin?

Answer 36

physical stimulation (most important) sight, sound, or smell of infant cervical dilation

Question 37

Functions of oxytocin

Answer 37

milk ejection uterine contraction establishment of maternal behavior

Question 38

What inhibits oxytocin?

Answer 38

Stress | oxytocin neurons repressed by catecholamines released during stress