Endocrine System

Question 0

Hormones

Answer 0

• chemicals secreted by endocrine glands
• diffuse directly into blood, carried through body
• main regulators of metabolism, growth and development, reprod.
• role in maintaining homeostasis

Question 1

Definitions

Answer 1

exocrine
-secrete into ducts, that empty into surface

endocrine
-ductless, secrete into intercellular space

target cell
-cell with specific receptor for a hormone

Question 2

Nonsteroid Hormones

Answer 2

• whole proteins, shorter chains of AA, or single AA
• trigger 2nd messengers when bind to receptors
  
  • ex. cyclic adenosine monophosphate (cAMP)
• provide communication b/w endocrine glands and target organs
• another molecule is 2nd messenger

Question 3

Steroid Hormones

Answer 3

• small, lipid-soluble
• can pass directly through plasma membrane of target cell
• bind to receptors w/in target nucleus and influence cell activity by acting on DNA
• response slow compared to nonsteroid hormones

Question 4

Regulation of Secretion

Answer 4

-controlled by homeostatic feedback

Negative Feedback

• reverses change
• ex. elevated sugar stim. release of insulin which causes level to drop back to normal

Positive Feedback

• amplify changes/push further from normal
• uncommon
• ex. during labour

Question 5

Prostaglandins (PG)

Answer 5

• aka tissue hormones
• role in communication and body function control
  
  • R, BP, gastro secretions, inflammation, reprod.
• produced in a tissue, then diffuses to act on cell w/in tissue
  
  • influences activities of neighbouring cells
• regulate cells by influencing production of cAMP
• immediate, short-term

3 classes

• Prostaglandin A (PGA)
• Prostaglandin E (PGE)
• Prostaglandin F (PGF)

Question 6

Adenohypophysis (aka ant. pit.)

Answer 6

• structure of endocrine glands
• tropic hormones (stim. another endocrine gland)
• TSH, ACTH, FSH, LH, GH, PRL

Question 7

TSH

Answer 7

• thyroid-stimulating hormone
• stimulates thyroid hormone
• tropic

Question 8

ACTH

Answer 8

• Adrenocorticotropic Hormone
• tropic
• stimulates adrenal cortex hormones

Question 9

FSH

Answer 9

• follicle-stimulating hormone
• Female
  
  • development of ovarian follicles
  • secretion of estrogens
• Male
  
  • stimulates seminiferous tubules to grow/prod. sperm

Question 10

LH

Answer 10

• luteinizing hormone
• tropic
• Female
  
  • stimulates maturation of ovarian follicle and ovum
  • stimulates secretion of estrogen, triggers ovulation
  • stimulates development of corpus luteum
• Male
  
  • stimulates interstitial cells of testes to secrete testosterone

Question 11

GH

Answer 11

• growth hormone
• stimulates growth in all organs
• increase in blood glucose
• hypoglycemia
  
  • too much insulin (low glucose)
• hyperglycemia
  
  • too much GH (high glucose)

Question 12

PRL

Answer 12

• prolactin

- stimulates breast development and milk secretion in pregnancy

Question 13

Neurohypophysis (aka post. pit.)

Answer 13

• releases, not produces hormones

- ADH, OT

Question 14

ADH

Answer 14

• antidiuretic hormone
• stimulates retention of water by kidneys
• acts to decrease urine volume
• hyposecretion =diabetes insipidus
  
  • large volumes of urine formed

Question 15

OT

Answer 15

• oxytocin
• stimulates uterine contraction at end of pregnancy
• stimulates release of milk into breast ducts

Question 16

Hypothalamus

Answer 16

• actual production of ADH and OT
• release controlled by nervous system
• travel directly through specialized blood capillary system to ant. pit. where hormones released/inhibited
• releasing H (RHs) stimulate ant. pit. to release H
• inhibiting H (IHs) inhibit ant. pit.’s secretion
• controls temp., appetite, thirst

Question 17

Thyroid Gland

Answer 17

• lies in neck below larynx
• stores large amounts of thyroid hormones, released when needed
• hypercalcemia-harmful excess of Ca in blood
• hyperthyroidism-oversecretion of thyroid hormones
• hypothyroidism-under-secretion of thyroid hormones

Thyroxine (T4) and Triiodothyronine (T3)
-stimulate metabolism

Calcitonin (CT)

• inhibits breakdown of bone
• causes decrease in blood Ca concentration

Question 18

Parathyroid Glands

Answer 18

• usually 4, back of thyroid glan
• cells sensitive to changing blood Ca levels
  
  • too much brain and heart cease
  • too little nerve cells overactive

Parathyroid Hormone (PTH)

• stimulate breakdown of bone
• increase in blood Ca concentration

Question 19

Adrenal Glands

Answer 19

• curve over top of each kidney

- each actually 2 separate endocrine glands

Question 20

Adrenal Cortex

Answer 20

• outer part of adrenal gland
• 3 zones
• hormones secreted are corticoids
• Mineralocorticoids, glucocorticoids, Sex Hormones

Question 21

Adrenal Medulla

Answer 21

• inner part of adrenal gland
• produce flight or fight
• epi and norepi (not essential for maintaining life)

Question 22

Mineralocorticoids (MCs)

Answer 22

-regulate electrolyte and fluid homeostasis

Aldosterone

• increase Na and decreased K in blood
• influences kidney tubules
• speeds up kidney reabsorption of water

Sex Hormones

• stimulate sex drive in female, negligible effect in male
• Androgens, male hormone in both

Question 23

Glucocorticoids (GCs)

Answer 23

• secreted by middle zone
• stimulate gluconeogenesis, increases blood glucose concentration
• anti-inflammatory, anti-immunity, anti-allergy effects
• promote breakdown of tissue proteins
• maintain normal BP
• produce stress
• cortisol is chief (aka hydrocortisone)

Question 24

Pancreatic Islets

Answer 24

- aka Islets of Langerhans - too small to see with microscope Glucagon - secreted by Alpha (A) cells - stimulates liver glycogenolysis - increase in blood glucose concentration Insulin - secreted by Beta (B) cells - promotes glucose entry into cells - decrease in blood concentration - normal is 70-110mg/100mL of blood - Type I DM - too little insulin - increased blood glucose - Type II DM - decreased insulin - prevents normal insulin effects

Question 25

Ovary

Answer 25

Estrogens -development and maintenance of female sexual characteristics Progesterone - promotes conditions required for pregnancy - secreted by corpus luteum

Question 26

Testis

Answer 26

- produce sperm and semen - Testosterone - secreted directly into blood - promotes development and maintenance of male sexual characteristics

Question 27

Thymus

Answer 27

- located in medistinum - has cortex and medulla - composed of lymphocytes - secretes thymosin - actually a group of hormones - development of immune system cells

Question 28

Placenta

Answer 28

- temporary endocrine gland - produces chorionic gonadotropins, estrogens, progesterone - conditions required during pregnancy

Question 29

Pineal Gland

Answer 29

- small gland near roof of 3rd ventricle of brain - secretes melatonin - inhibits tropic hormones regulating ovaries - regulates body's internal clock