Alberta Biology 30: Endocrine System

What is an endocrine gland?

Ductless; secretes hormones directly into the bloodstream; migrate throughout the body to target

What is an exocrine gland?

Ducts; secret chemicals directly to target site; local area

What kind of gland is the pancreas?

Both exo and endo.

What are the two types of hormones?

Steroid/nonsteroid

What are steroid hormones? Give an example.

Lipids; easily move through cell membranes; bind to receptors inside cell. Example: aldosterone

What are nonsteroid hormones? Give an example.

Proteins/peptides; bind to receptors on cell membrane; initiates change inside cell. Example: ADH

What is a tropic hormone? Give an example.

Tells a gland to release another hormone. Example: GnRH

What is a non tropic hormone? Give an example.

Causes a direct effect on a cell. Example: estrogen.

What is the difference between a negative and positive feedback loop?

Negative - leads to instability; correcting system.

Positive - leads to instability; increases magnitude of input.

What are the two positive feedback loops we must memorize for this course? HINT: they both have to do with the female body.

Estrogen & LH

Oxytocin & Uterine Contractions

Where is thyroxine produced? What is it made of?

Thyroid gland. Iodide.

Which hormone controls the release of thyroxine? Where is it released from?

TSH (thyroid stimulating hormone); anterior pituitary.

What is the target for thyroxine?

All tissues (heart, muscles, lungs, etc).

What stimulates the release of thyroxine?

Cold, stress, growth.

What is the purpose of thyroxine?

To increase cellular respiration (increase glucose consumption & heat)

What is Grave's disease? What are some symptoms?

Overproduction of thyroxine - immune system attacks the thyroid gland and muscles around the eyes. Symptom: bulging eyes.

Which hormone is responsible for the growth of long bones and muscles? Where is it produced?

hGH (human growth hormone); anterior pituitary

What stimulates the release of hGH?

Puberty, exercise, sleep, starvation

What does the oversecretion of hGH lead to in adults? In children?

Children = gigantism

Adults = acromegaly

What does the under secretion of hGH lead to?

Dwarfism

Which two hormones regulate blood calcium levels?

PTH (parathyroid hormone) and calcitonin

TIP: paRathyroid = Raise blood calcium

caLcitonin = Lower blood calcium

Where is PTH found? What is its stimulus? Where does it target?

Parathyroid gland; low blood calcium levels; bones, small intestine, kidneys.

What effect does PTH have on the bones? Kidneys? Intestine?

Bones = breakdown and release calcium.

Kidneys = reabsorption of calcium into blood.

Intestine = increase absorption of calcium.

What is the stimulus for the release of calcitonin? Where does it target? What is the effect?

High blood calcium levels; bones; puts calcium back into bones.

What are the purpose of beta cells in the pancreas?

Release insulin.

What are the purpose of alpha cells in the pancreas?

Release glucagon.

What is the purpose of insulin? What are the targets?

DECREASE blood glucose. All cells, liver, adipose tissue.

What is the purpose of glucagon? What is the target?

INCREASE blood glucose. Liver.

What is diabetes mellitus? What are the two types?

Difficult regulating blood sugar levels.

Type 1 - autoimmune, low insulin levels.

Type 2 - insulin insensitivity over time.

What three hormones regulate stress? Where are they released from?

Cortisol, epinephrine, adrenaline. Adrenal glands.

What hormone stimulates the adrenal glands to release cortisol? Where is is produced?

ACTH (adrenocorticotropic hormone); anterior pituitary

For which hormone is the stimulus LOW GRADE stress, injury, or exercise?

Cortisol.

TIP: Cortisol = Coping

What is the purpose of cortisol? How does it achieve this?

Increase glucose levels for the brain.

Liver - converts amino acids to glucose

All cells - stop absorbing glucose

Muscles - breakdown - release amino acids to be converted to glucose.

Adipose tissue - release fat to be converted

Which gland produces ADH? Which gland releases it?

Hypothalamus; posterior pituitary.

Where does ADH target? What is it's purpose?

Nephrons of kidney & arterioles; increases water reabsorption & increases blood pressure.

Which type of diabetes is caused by low ADH production?

Diabetes insipidus.

Which gland releases aldosterone?

Adrenal glands (cortex)

Where does aldosterone target? What is the DIRECT and INDIRECT effect?

Kidney; sodium ion reabsorption; H20 reabsorption.

What stimulates the release of aldosterone?

Low blood sodium, low blood pressure, hemorrhaging

What hormone stimulates the adrenal glands to release aldosterone? Where is is produced?

ACTH (adrenocorticotropic hormone); anterior pituitary

What is the function of estrogen in females?

Development of secondary sex characteristics, thickening of endometrium.

What is the function of progesterone in females?

Prevents uterus from contracting, maintains endometrium.

TIP: Progesterone = Pregnancy

What is the function of testosterone in males?

Stimulates primary & secondary sex characteristics (growth of penis, testes, etc); indirectly stimulates spermatogenesis

Where is FSH produced/released? What is the role of FSH in males? Females?

Anterior pituitary

Males = tells Sertoli cells to begin spermatogenesis in sem. tubules.

Females = tells follicles in ovaries to develop.

Where is LH produced/released? What is the role of LH in males? Females?

Anterior pituitary

Males = tells interstitial cells to produce testosterone.

Females = triggers ovulation & estrogen/progesterone secretion from corpus luteum.

Which hormone stimulates the release of FSH and LH? Where is it produced?

GnRH (gonadotropin releasing hormone); hypothalamus.

What hormone is responsible for the opening of the cervix and loosening of ligaments in the pelvis during parturition? What structure produces it?

Relaxin; corpus luteum

What hormone is responsible for uterine contractions AND the release of breast milk? Where is it produced? Released?

Oxytocin; hypothalamus; posterior pituitary.

What is the role of prolactin? Where is it produced? Released?

Production of breast milk; anterior pituitary (releases and produces)

What are the hormones produced and secreted by the anterior pituitary gland?

PRL, hGH, FSH, ACTH, TSH, LH.

Which hormones are released by the posterior pituitary gland? Where are these hormones produced?

oxytocin & ADH; hypothalamus.