Endocrine System Part 3

Question 1

Primary adrenal insufficiency (Addison’s disease)

Answer 1

Loss of adrenal cortical function

• Hyponatremia
• Hyperkalemia
• Low blood pressureAldosterone normally:
• Promotes sodium (Na⁺) reabsorption
• Promotes potassium (K⁺) excretion
• Helps retain water (indirectly through sodium
  retention)
• Maintains blood pressure and blood volume
  In Addison’s:
• Hyponatremia
• Hyperkalemia
• Low blood pressure

Question 2

Adrenal Insufficiency

Answer 2

Cortisol - chronically lower than normal

Symptoms:
* Weakness
* Lethargy
* Loss of appetite
* Low blood pressure
* Cortisol permissive of epinephrine
* Low blood sugar
* Especially after fasting
* Loss of the normal metabolic actions of cortisol

Question 3

Aldosterone normally:

Answer 3

• Promotes sodium (Na⁺) reabsorption
• Promotes potassium (K⁺) excretion
• Helps retain water (indirectly through sodium
  retention)
• Maintains blood pressure and blood volume

Question 4

Cushing’s Syndrome

Answer 4

Excess cortisol in the blood, even when nonstressed

• Primary defect
  E.g., a cortisol-secreting tumor of the adrenal
• Secondary defect
  Usually due to an ACTH-secreting tumor of the pituitary gland

In Cushing’s disease
Uncontrolled catabolism of bone, muscle, skin, and other organs

• Osteoporosis
• Muscles weakness
• Blood sugar increases to levels observed in diabetes mellitus
• Immunosuppression
• Redistribution of fat (buffalo hump and moon face)
• Hypertension (high blood pressure)
• Treatment of Cushing’s Syndrome depends on the cause.
• Surgical removal of the pituitary tumor
• Adrenalectomy

Question 5

Major hormones

Answer 5

Growth hormone and “Insulin-like” growth factors
* Thyroid hormones
* Insulin
* Sex hormones (testosterone, estrogen)
* Cortisol (anti-growth effects)

Question 6

Which two organs are mainly responsible for metabolizing or excreting hormones?

Answer 6

Kidneys and liver

Question 7

Hormone secretion from the adrenal medulla is directly controlled by ______.

Answer 7

neural stimulation

Question 8

Increased insulin secretion causes ______.

Answer 8

lowered blood glucose concentration

Question 9

Peptide and catecholamine hormones exert their effects on target cells by ______.

Answer 9

influencing the generation of intracellular second-messenger molecules

Question 10

The type of hyposecretion where the endocrine gland is not damaged but is receiving too little stimulation by its tropic hormone is called
_________ hyposecretion.

Answer 10

secondary

Question 11

Anterior pituitary hormones that stimulate target glands to secrete their hormones are called
_________ hormones. They might also stimulate the growth of the target glands, an effect specifically referred to as a(n) ________ effect.

Answer 11

tropic

trophic

Question 12

Hormones released by the anterior pituitary gland

Answer 12

Thyroid-stimulating hormone
Adrenocorticotropic hormone
Follicle-stimulating hormone
Luteinizing hormone
Prolactin

Question 13

Hypophysiotropic hormones are neurosecretions released by the hypothalamus that influence the secretion of hormones from the anterior pituitary gland. Which of these are hypophysiotropic hormones?

Answer 13

Dopamine
Gonadotropin-releasing hormone
Somatostatin
Corticotropin-releasing hormone

Question 14

Hormones (other than cortisol) that are released during stress include

Answer 14

vasopressin, ADH, or antidiuretic hormone and aldosterone

Question 15

CRH

Answer 15

=ACTH= Cortisol

Question 16

Physiological Functions of
Cortisol

Answer 16

• Permits action of epinephrine and norepinephrine
• Muscles
• Blood vessels
• Maintains plasma glucose concentration
• Maintains metabolic enzymes required to produce
  glucose between meals
• Decreases inflammatory response events
• Capillary permeability
• Prostaglandin & leukotriene production
• Important for fetal development

Question 17

Calcium storage, absorption into the body and excretion from the body occur at 3 main sites:

Answer 17

1. Bones
   * Storage
2. Kidneys
   * Excretion and reabsorption
3. Small & Large Intestines
   * Absorption

Question 18

Calcitonin

Answer 18

Secreted by parafollicular cells of the
thyroid gland in response to high plasma calcium

• Inhibits osteoclasts
• Decreases plasma calcium

Question 19

Two major hormones regulate plasma calcium concentration:

Answer 19

1. Parathyroid hormone
2. 1,25-dihydroxyvitamin D
   * Calcitonin plays a limited role

Question 20

PTH Actions:

Answer 20

1. Stimulates osteoclasts= free Ca2+
2. Stimulates formation of 1,25(OH)2D
   * Increases Ca2+ absorption in intestine
3. Stimulates increased Ca2+ absorption in the kidneys
4. Decreases resorption of phosphate ions in the
   kidneys= excretion ↑
   * Released into blood with Ca2+ in steps #1 & 2
   * Keeps plasma phosphate low