Ex 4 - Pituitary and Adrenal Glands

Question 1

What are hormones comprised of?

Answer 1

Proteins, aa derivatives, or steroids

Question 2

Describe hormone release

Answer 2

1. Immediate release (preformed substrate)

2. Stimulation of synthesis and delayed release

Question 3

Describe hormones as controlling elements

Answer 3

The hormone that is produced acts as its own negative feedback loop

Question 4

Describe hormones as controlled variables

Answer 4

Secondary hormones feedback to primary endocrine organs to shut down production of ‘primary’ hormones

Question 5

What bone is poorly formed in the head of the horse?

allows for compression of the overlying structures

Answer 5

Sella turcica bone

Question 6

Name 3 regions in the pituitary gland

Answer 6

1. Pars nervosa
2. Pars intermedia
3. Pars distalis

Question 7

What are the 3 cells of the pars distalis?

Answer 7

1. Acidophils
   - Prolactin
   - Growth hormone (major counter regulatory hormone to insulin)
2. Basophils
   - FSH/LH
   - TSH
   - ACTH
3. Chromophobes
   - lack secretory content

Question 8

What is released from the pars intermedia?

Answer 8

Melanocyte-stimulating hormone (MSH)

*important in the dopamine regulatory pathway and pathogenies of equine PPID

Question 9

What are the 3 zones of the adrenal cortex (outer to inner)? and what hormones do each release?

Answer 9

1. Zona glomerulosa = salt
   - mineralocorticoids (e.g. aldosterone)
2. Zona fasciculata = sugar
   - glucocorticoids (e.g. cortisol)
3. Zona reticularis = sex
   - androgens (e.g. DHA)

*Remember GFR = layers

Question 10

What stimulates the release of ADH?

Answer 10

Hyperosmolarity and hypovolemia

Question 11

ADH and Nephrogenic diabetes insipidus

Answer 11

Kidney’s don’t respond to ADH

Congenital defect

Question 12

Mineralcorticoid regulation (aldosterone)

Answer 12

Release stimulated by falling or rising BP and high K+

Promotes salt retention and promotes RAAS activation

Question 13

What is the primary function of Gucocorticoids?

Answer 13

induce hepatic gluconeogenesis

• inhibits glucose uptake and metabolism in peripheral tissues
• synergies with glucagon actions
• directly increases lipolysis and redistributes fats

Question 14

What are some other functions of glucocorticoids?

Answer 14

• promotes protein catabolism
• promotes diuresis (increases GFR)
• prevents arachidonic acid metabolism
• surpasses lymphocyte and MO fxn

Question 15

How do animals with glucocorticoid abnormalities present?

Answer 15

1. Pot belly appearance
2. Hepatomegaly
3. PU/PD (ADH is inhibited)
4. Secondary infections (immune system suppressed)

Question 16

Four major mechanisms of Endocrine dz

Answer 16

1. Primary hyperfunction (most common)
   - commonly caused by neoplasia
2. Primary hypofunction
3. Secondary hyper function
4. Secondary hypo function
   - loss of a trophic stimulus leads to a loss of stimulation/feedback & atrophy
   - target tissue is unable to respond to hormone –> endocrine organ works harder –> eventually fails

Question 17

Hyperfunction

Answer 17

Almost always due to some proliferative disease

*neoplasia

Question 18

Hypofunction

Answer 18

Usually a degenerative or hypo plastic process

Question 19

How do we classify lesions?

Answer 19

Proliferative

• hyperplasia
• neoplasia (functional)

Destructive

• hypoplasia
• atrophy
• inflammatory
• neoplasia (non-functional)
• degenerative

Question 20

Key points - mechanisms of endocrine dz

Answer 20

1. Since hormones often have multiple fxns, secondary lesions in distant organs is common
2. There are key clinical/pathologic features that should suggest a particular endocrine disease.
3. Neoplasia is a common process causing endocrine disease
4. Other neuro manifestations may be present with primary disease of the pituitary