Biol 224: Lecture 27a Pituitary Glands: Hormones

10/21 Kahoots

Hormones of the adenohypophysis is referred to as what?

Tropic hormones: Hormone that causes glands to release another hormone

Thyroid Stimulating Hormone (TSH)

Also called thyrotropin

Triggers the release of hormones from thyroid gland

What promotes the release of TSH

Thyrotropin releasing hormone (TRH) from hypothalamus

Adrenocorticotropic hormone (ACTH) 

Also called corticotropin 

Stimulates the release of glucocorticoids from adrenal cortex 

What promotes the release of ACTH?

Corticotropin releasing hormone (CRH) from the hypothalamus

Gonadotropins

Follicle stimulating hormone (FSH)

Luteinizing hormone (LH)

What promotes the release of gonadotropins?

Gonadotropin releasing hormone (GnRH) from hypothalamus

Gonadotropins don’t get released until when?

Puberty 

Follicle stimulating hormone (FSH)

Stimulates follicle development (egg maturation) and estrogen secretion in ovaries

Stimulates sperm production in sustentacular cells of testes

What is needed to release GnRH?

Leptin

When do females get their eggs?

Females are born with all the eggs they’ll ever have

Luteinizing hormone (LH)

Causes ovulation and progestin production in ovaries 

Causes androgen production in testes 

Prolactin (PRL)

Stimulates the development of mammary glands and milk production

In what population is prolactin most commonly found in?

Breastfeeding mothers

Prolactin Releasing Hormone

Released by hypothalamus

Inhibited by inhibiting hormone (ex: dopamine)

Melanocyte Stimulating Hormone (MSH)

Stimulates melanocytes to produce melanin pigment in skin and other locations

In humans very little MSH is produced by pituitary gland

What releases melanocyte stimulating hormone?

Pars intermedia which is technically a part of adenohypophysis

Growth Hormone (GH or somatotropin)

Tropic effect: cause release of somatomedins (IGF-1) from liver

Direct effect — increase cell division in epithelial and connective tissue, enhance break down of lipid and glycogen energy reserve

Somatomedins

Cause increase in amino acid uptake in skeletal muscle cells, cartilage cells — stimulates protein synthesis and cell growth

What is GH release controlled by?

GH releasing hormone (GH-RH) and GH inhibiting hormone (GH -IH) from hypothalamus

Neurohypophysis

Contains axon terminals of hypothalamic nerve cells — secretes hormones into blood

Hormones secreted by adenohypophysis

Follicle Stimulating Hormone

Luteinizing hormone

Adrenocorticotropic hormone

Growth Hormone

Thyroid Stimulating Hormone

Melanocyte Stimulating Hormone (pars intermedia)

Prolactin

Hormones secreted by Neurohypophysis

Antidiuretic hormone and Oxytocin 

Antidiuretic hormone (ADH)

Decreases the amount of water lost at the kidneys — decreases urine production

Elevates blood pressure 

Oxytocin

Stimulates contractile cells in mammary glands

Stimulates smooth muscle cells in uterus

What is oxytocin’s role in childbirth?

Oxytocin causes the uterus to contract which helps the baby come out

Also secretes during breastfeeding —> releases milk

Why is oxytocin called the “bonding” hormone?

Released when you create bonds with people

What is ADH’s role in alcohol consumption?

When you’re dehydrated you produce more ADH, alcohol blocks this from happening, meaning diuretic which means more pee and less reabsorption → hangover 

Draw feedback control of thyroid hormone

Draw the feedback control of Adrenocorticotropic hormone