Chapter 39: Endocrine Function (exam 2)

What is the endocrine system?

A collection of glands and cells that secrete hormones into the bloodstream

What are hormones?

Blood-borne chemical messengers that affect distant target cells

What functions do hormones regulate?

Growth, metabolism, reproduction, and fluid balance

What is neurocrine signaling?

Hormone secretion into the bloodstream by neurons

What is endocrine signaling?

Hormone secretion into the bloodstream by endocrine glands

What is paracrine signaling?

Hormone affects nearby cells

What is autocrine signaling?

Hormone affects the cell that secreted it

What are water-soluble hormones?

Hormones that travel freely in blood and bind cell surface receptors

What are lipid-soluble hormones?

Hormones that require transport proteins and bind intracellular receptors

What is the mechanism of action of water-soluble hormones?

Second messenger cascades

What is the mechanism of action of lipid-soluble hormones?

Alter gene transcription

What are examples of lipid-soluble hormones?

Cortisol, aldosterone, testosterone, estrogen, T3, T4

What are examples of water-soluble hormones?

Insulin, ADH, ACTH, GH, FSH, LH

What does Gs activation increase?

cAMP

What does Gq activation produce?

DAG and IP3

What hormone uses a protein kinase receptor?

Insulin

What hormones use JAK-associated receptors?

Growth hormone and prolactin

What is positive feedback?

A response that increases hormone secretion

What hormone uses positive feedback during labor?

Oxytocin

What is negative feedback?

A response that decreases hormone secretion

What is receptor up-regulation?

Increase in receptor number due to low hormone levels

What is receptor down-regulation?

Decrease in receptor number due to high hormone levels

What is permissiveness?

One hormone increases receptors for another hormone

How are water-soluble hormones excreted?

In urine

How are lipid-soluble hormones transported?

Bound to plasma proteins

What hormone does TRH stimulate?

TSH and prolactin

What hormone does CRH stimulate?

ACTH

What hormone does GHRH stimulate?

Growth hormone

What hormones does GnRH stimulate?

FSH and LH

What are the two posterior pituitary hormones?

Oxytocin and ADH

What does oxytocin do?

Causes uterine contractions and milk ejection

What does ADH do?

Increases water reabsorption in the kidneys

What is another name for ADH?

Vasopressin

What does growth hormone stimulate in the liver?

IGF-1 production

What effect does growth hormone have on adipose tissue?

Increases lipolysis

What effect does growth hormone have on skeletal muscle?

Increases protein synthesis

What inhibits growth hormone release?

IGF-1

What does prolactin do?

Stimulates milk production

What inhibits prolactin release?

Dopamine

What stimulates prolactin release?

TRH

What does FSH do in females?

Stimulates follicle development and estrogen production

What does LH do in females?

Triggers ovulation

What does FSH do in males?

Stimulates spermatogenesis

What does LH do in males?

Stimulates testosterone production

What hormones are produced by thyroid follicular cells?

T3 and T4

What is the major action of T3 and T4?

Increase metabolic rate

Which thyroid hormone is most active?

T3

What hormone is released by parafollicular cells?

Calcitonin

What does calcitonin do?

Lowers serum calcium

What stimulates calcitonin release?

Hypercalcemia

What hormone is released by parathyroid chief cells?

PTH

What does PTH do?

Increases serum calcium

What stimulates PTH release?

Hypocalcemia

What is calcitriol?

The active form of vitamin D

What does calcitriol increase?

Calcium absorption from GI tract and kidneys

What does the adrenal medulla secrete?

Epinephrine and norepinephrine

What does the zona glomerulosa secrete?

Aldosterone

What does aldosterone do?

Retains sodium and water and excretes potassium

What does the zona fasciculata secrete?

Cortisol

What does cortisol do?

Increases blood glucose and responds to stress

What does the zona reticularis secrete?

Androgens

What is the adrenal cortex mnemonic?

GFR = Salt Sugar Sex

What is primary hyposecretion?

Endocrine gland fails to secrete enough hormone

What is secondary hyposecretion?

Tropic hormone deficiency causes low hormone secretion

What is primary hypersecretion?

Endocrine gland secretes excess hormone

What is secondary hypersecretion?

Excess tropic hormone causes excess hormone secretion

What is hyporesponsiveness?

Target tissue resistance to hormone