things to know biol 220 exam 3!

What does TRH stand for?

Thyrotropin-releasing hormone; made by the hypothalamus.

What does TRH stimulate?

Anterior pituitary secretion of TSH; it can also stimulate prolactin.

What does CRH stand for?

Corticotropin-releasing hormone; made by the hypothalamus.

What does CRH stimulate?

ACTH secretion from the anterior pituitary, especially in prolonged stress.

What does GnRH stand for?

Gonadotropin-releasing hormone; made by the hypothalamus.

What does GnRH stimulate?

Anterior pituitary release of both FSH and LH.

What does GHRH stand for?

Growth hormone-releasing hormone; made by the hypothalamus.

What does GHRH stimulate?

Growth hormone (GH) secretion from the anterior pituitary.

What is PIH?

Prolactin-inhibiting hormone, also called dopamine; inhibits anterior pituitary prolactin release.

What does somatostatin do?

Inhibits anterior pituitary GH secretion and can inhibit TSH secretion.

How many hypothalamic hormones are grouped in your professor's lecture?

Eight: six regulate the anterior pituitary and two are stored in the posterior pituitary.

How are the six anterior-pituitary-regulating hypothalamic hormones divided?

Four releasing hormones (TRH, CRH, GnRH, GHRH) and two inhibitors (dopamine/PIH, somatostatin).

How do hypothalamic regulatory hormones reach the anterior pituitary?

Through the hypophyseal portal blood system, not through direct axons.

What does FSH stand for, and where is it made?

Follicle-stimulating hormone; produced by the anterior pituitary in response to GnRH.

What are the targets and effects of FSH?

Ovaries: supports follicle development; testes: acts on Sertoli cells to support sperm production.

What does LH stand for, and where is it made?

Luteinizing hormone; produced by the anterior pituitary in response to GnRH.

What does LH do in the ovaries?

An LH surge triggers ovulation and formation of the corpus luteum, which secretes progesterone.

What does LH do in the testes?

Stimulates Leydig (interstitial) cells to synthesize testosterone from cholesterol.

How does LH stimulate testosterone production?

LH binds a cell-surface receptor, triggering intracellular signals that activate steroid-synthesis processes.

What is the key difference between FSH and LH?

FSH supports follicle development and sperm production; LH triggers ovulation and stimulates sex-hormone production.

What does TSH stand for, and where is it made?

Thyroid-stimulating hormone; made by the anterior pituitary after stimulation by TRH.

What is the target and effect of TSH?

Thyroid gland; stimulates thyroid growth and secretion of thyroid hormone (TH).

What is the thyroid hormone pathway?

Hypothalamus TRH → anterior pituitary TSH → thyroid TH → increased basal metabolic rate.

Does TSH directly increase metabolic rate?

No. TSH stimulates the thyroid; thyroid hormone acts on body tissues to increase metabolic activity.

What does ACTH stand for, and where is it made?

Adrenocorticotropic hormone; made by the anterior pituitary after stimulation by CRH.

What is the target and effect of ACTH?

Adrenal cortex; stimulates secretion of glucocorticoids, especially cortisol.

What is the prolonged-stress hormone pathway?

Hypothalamus CRH → anterior pituitary ACTH → adrenal cortex cortisol.

Why does cortisol rise during prolonged stress?

It helps coordinate energy availability by changing glucose, fat, and protein metabolism across tissues.

What does PRL stand for, and where is it made?

Prolactin; produced by the anterior pituitary.

What is prolactin's main target and function?

Mammary glands; stimulates milk production.

How is prolactin regulated?

Dopamine normally inhibits it; TRH can stimulate it. Its role is especially important during pregnancy and breastfeeding.

What is the difference between prolactin and oxytocin?

Prolactin stimulates milk production; oxytocin stimulates milk ejection. Oxytocin is released from the posterior pituitary.

What does GH stand for, and where is it made?

Growth hormone (somatotropin); produced by the anterior pituitary.

What stimulates and inhibits GH secretion?

GHRH stimulates GH; somatostatin inhibits GH.

What tissues does GH affect?

Many tissues, especially bone, muscle, and fat; it supports growth and influences metabolism.

How does GH support tissue growth?

It promotes growth-related processes, including cell division and tissue-building, partly through IGF-1.

What are the six anterior pituitary hormones emphasized in Lecture 13?

FSH, LH, TSH, ACTH, prolactin (PRL), and growth hormone (GH).

Which anterior pituitary hormones respond to GnRH?

FSH and LH.

Which anterior pituitary hormone stimulates the thyroid gland?

TSH, released in response to hypothalamic TRH.

Which anterior pituitary hormone stimulates the adrenal cortex?

ACTH, released in response to hypothalamic CRH.

Which anterior pituitary hormone stimulates milk production?

Prolactin (PRL); milk ejection is triggered by oxytocin.

Which anterior pituitary hormone promotes growth in bone and muscle?

Growth hormone (GH), stimulated by GHRH.

Why does the hypothalamus use both releasing and inhibiting hormones?

To increase or decrease pituitary secretion as needed and help maintain homeostasis.

What is a tropic hormone?

A hormone that acts on another endocrine gland, often stimulating its hormone secretion; examples include TSH and ACTH.

Where is cortisol produced: anterior pituitary or adrenal cortex?

Adrenal cortex. The anterior pituitary produces ACTH, which stimulates cortisol secretion.

Where is testosterone produced after LH stimulation?

Leydig (interstitial) cells of the testes, not the pituitary.

What is the corpus luteum and why does it matter?

A temporary ovarian structure formed after ovulation that secretes progesterone.

Which two hormones are released by the posterior pituitary?

ADH (vasopressin) and oxytocin.

Where are ADH and oxytocin produced?

In neuroendocrine cells of the hypothalamus.

What is the posterior pituitary's role in hormone secretion?

It stores and releases hormones produced in the hypothalamus.

How do hypothalamic hormones reach the posterior pituitary?

They travel down neuronal axons through the infundibulum.

What triggers hormone release from posterior pituitary nerve endings?

Action potentials arriving at the axon terminals.

What is another name for antidiuretic hormone (ADH)?

Vasopressin.

What is the primary target of ADH?

The kidneys, especially collecting duct cells.

What is the main function of ADH?

It increases kidney water reabsorption and helps conserve body water.

What does antidiuretic mean?

Reducing urine production.

What is diuresis?

Production of urine, especially a large volume of dilute urine.

What is blood osmolarity?

The concentration of dissolved particles in blood plasma.

What happens to blood osmolarity when the body loses water?

It generally increases because dissolved particles become more concentrated.

Which receptors detect increased blood osmolarity?

Osmoreceptors in the hypothalamus.

How does dehydration affect ADH secretion?

Dehydration typically increases ADH release.

Which gland releases stored ADH into the bloodstream?

The posterior pituitary.

What does ADH do to water reabsorption in the kidneys?

It increases water reabsorption back into the bloodstream.

How does ADH affect urine volume?

It decreases urine volume.

How does ADH affect urine concentration?

It makes urine more concentrated.

Why is ADH important during dehydration?

It reduces water loss in urine and helps maintain blood volume.

What is the ADH pathway during dehydration?

Water loss → higher osmolarity → hypothalamus → posterior pituitary ADH → kidneys conserve water.

What happens when less water is lost through urine?

Body water and blood volume are better maintained.

What is aldosterone's main kidney effect?

It increases sodium reabsorption, helping regulate fluid balance.

How do ADH and aldosterone work together?

ADH conserves water; aldosterone promotes sodium retention, supporting fluid balance.

What does synergistic mean in hormone signaling?

Two hormones act together to produce a coordinated or enhanced effect.

What happens to ADH release when blood osmolarity returns toward normal?

The stimulus for ADH secretion decreases through negative feedback.

How is the posterior pituitary different from the anterior pituitary?

Posterior stores/releases hypothalamic hormones; anterior produces its own hormones.

Which pituitary division is made primarily of nervous tissue?

The posterior pituitary.

Which pituitary division is made primarily of glandular epithelial tissue?

The anterior pituitary.

Why does the posterior pituitary contain many capillaries?

To release stored hormones into the bloodstream.

What is oxytocin's abbreviation?

OT.

Where is oxytocin produced and released?

Produced in the hypothalamus; stored and released by the posterior pituitary.

What are two major effects of oxytocin?

Uterine contractions and milk ejection.

Which hormone stimulates milk production?

Prolactin from the anterior pituitary.

Which hormone stimulates milk ejection?

Oxytocin from the posterior pituitary.

What is a neuroendocrine reflex?

A neural stimulus triggers hormone release into the blood.

What can trigger oxytocin release during breastfeeding?

Sensory signals from infant suckling.

What can trigger oxytocin release during labor?

Stretching of the cervix.

What type of feedback can reinforce oxytocin-driven labor contractions?

Positive feedback: stretching stimulates oxytocin, increasing contractions.

What happens when ADH levels are too low during dehydration?

The kidneys conserve less water, leading to more dilute urine and water loss.

named for the effect on gamete production

FSH

name means “against urine”

ADH

name means “near the thyroid”

PTH

named for directly affecting the thyroid

TSH

name for the number of iodine molecule in the hormone

T3

name means “promoting milk production”

PRL

Named for causing the release of hormone affecting the gonads

GnRH

Named for stimulating the cortex of the adrenal gland

ACTH

Named for producing the conversion of the follicle into a corpus luteum

LH

Named for causing the release of ACTH

CRH

Insulin converts glucose to triglycerides

adipose tissue

PTH stimulates calcium release

bone tissue

GH stimulates hypertrophy

skeletal muscle tissue

Erythropoietin increases production

blood tissue