Mamm Phys Exam 3- Full Set

What are the three classes of hormones?

Proteins/polypeptides, steroids, amines

What determines a hormone’s mechanism of action?

Its chemical structure (class)

What is the defining feature of endocrine hormones?

Released into bloodstream to act on distant targets

What is the difference between paracrine and autocrine signaling?

Paracrine acts on nearby cells; autocrine acts on the same cell

What is the ultimate result of hormone-receptor binding?

Change in protein activity in the cell

Which hormones act via intracellular receptors?

Steroid and thyroid hormones

Which hormones act via membrane receptors?

Peptide hormones and catecholamines

What type of feedback controls most hormone secretion?

Negative feedback

Name two examples of positive feedback in the endocrine system

Oxytocin (labor) and LH surge (ovulation)

How does the hypothalamus communicate with the anterior pituitary?

Blood (hypothalamohypophyseal portal system)

How does the hypothalamus communicate with the posterior pituitary?

Neural signals

Which hormones are released from the posterior pituitary?

ADH and oxytocin

What is the main function of ADH?

Increases water reabsorption in kidneys (aquaporins)

What is the mechanism of ADH action?

cAMP → aquaporin insertion into collecting ducts

What is the function of oxytocin during labor?

Stimulates uterine contractions (positive feedback)

What is the function of oxytocin in lactation?

Milk ejection (let-down)

Which anterior pituitary hormone acts directly on tissues?

Growth hormone (GH)

What are the major metabolic effects of GH?

↑ protein synthesis, ↑ fat utilization, ↓ glucose utilization

What hormone mediates GH effects on growth?

IGF-1 (somatomedin C)

What stimulates GH release?

Sleep, exercise, stress, fasting

What inhibits GH release?

Somatostatin and IGF-1

What is gigantism?

Excess GH before puberty

What is acromegaly?

Excess GH after puberty

What are the main thyroid hormones?

T3 (triiodothyronine) and T4 (thyroxine)

Which thyroid hormone is more potent?

T3

Where are thyroid hormones stored?

In colloid bound to thyroglobulin

What is required to make thyroid hormones?

Iodine

How are T3 and T4 transported in blood?

Bound to plasma proteins

What is the main effect of thyroid hormones?

Increase basal metabolic rate (BMR)

What hormone stimulates thyroid hormone release?

TSH

What happens to TSH when T3/T4 levels rise?

TSH decreases (negative feedback)

What are key symptoms of hyperthyroidism?

Weight loss, heat intolerance, tachycardia, nervousness

What are key symptoms of hypothyroidism?

Fatigue, weight gain, cold intolerance, slow heart rate

What are the three zones of the adrenal cortex?

Zona glomerulosa, zona fasciculata, zona reticularis

What does the zona glomerulosa secrete?

Aldosterone

What does the zona fasciculata secrete?

Cortisol

What does the zona reticularis secrete?

Androgens

What is the main function of aldosterone?

Increase Na⁺ and water reabsorption, decrease K⁺

What is the main function of cortisol?

Increase blood glucose and respond to stress

How does cortisol affect protein metabolism?

Increases protein breakdown

How does cortisol affect fat metabolism?

Increases fat breakdown

What is a key anti-inflammatory effect of cortisol?

Suppresses immune response and inflammation

What is Cushing’s syndrome?

Excess cortisol

What is Addison’s disease?

Deficiency of cortisol and aldosterone

Which cells of the pancreas secrete insulin?

Beta cells

Which cells of the pancreas secrete glucagon?

Alpha cells

What is the main effect of insulin?

Lowers blood glucose

What is the main effect of glucagon?

Raises blood glucose

What does insulin do to glucose uptake?

Increases uptake in muscle and fat cells

What does insulin do to glycogen?

Increases glycogen synthesis

What does insulin do to fat metabolism?

Increases fat storage

What does insulin do to protein metabolism?

Increases protein synthesis

What happens in insulin deficiency?

Hyperglycemia and ketosis

What are the main actions of glucagon?

Glycogen breakdown and gluconeogenesis

What is the relationship between insulin and glucagon?

They have opposite effects

What happens to insulin levels when blood glucose rises?

Insulin increases

What happens to glucagon when blood glucose rises?

Glucagon decreases