Integumentary System And Endocrine System

Question 1

THE SKIN - structure

Answer 1

• Thickness varies throughout the body
• 3 layers: epidemis, dermis and subcutanens layer

Question 2

EPIDERMIS

Answer 2

• Outermost layer
• Structure: stratified scquamous epithelial with 20-30 layers of cells; has pores; and has pain receptors with free nerve endings at the bottom

Question 3

DERMIS

Answer 3

• Second lager
• Structure: connective tissue with fibroblasts producing collagen and lastin; has the skin’s blood vessels; and has hair follicles, sebaceous (fat) glands, and sweat glands

Question 4

SUBCUTANEOUS LAYER - structure

Answer 4

• Deepest layer
• Contains fat cells - adipocytes → store fat keeping body temperature

Question 5

SUBCUTANEOUS LAYER - functions

Answer 5

• Protects against microbes (by activating the immune system), UV-light, and mechanical/chemical damage
• Regulates body temperature → forms goose bumps when cold
• Provides sensation with different sense organs → cutaneous sensation = receptors in skin for pain, touch, pressure, and vibration

Question 6

Regulation of body temperature

Answer 6

• Homeostatic regulation by negative feedback
• Increased body temp. → blood warm → hypothalamas registers this → signal to sweat glands → we start to sweat → cool down body and body temp. decreases → hypothalamus registers and sends stop signals → stops sweating
• Hypothalamus can register by feeling blood temp. when blood reaches it

Question 7

THE ENDOCRINE SYSTEM

Answer 7

• The active substances = hormones → transported by the blood and interstitial fluids
• 2 types: water-soluble and lipid (fat)-soluble
• Hypothalamus in charge of the system

Question 8

Water-soluble hormones

Answer 8

• Amines and peptides (short proteins)
• Transport: Free in blood plasma → diffused or filtrated out of capillaries → binds to receptors in membrane of target cells
• Effect: Activates a secondary messenger system inside the cell → cell is activated

Question 9

Lipid-soluble hormones

Answer 9

• Steroids
• Transport: attached to transport protein in blood stream (fat + protein = polar molecule = water-soluble) → diffuse in capillaries → interstitial fluid → diffuse through membrane of target cells → binds to receptors on nucleus inside cell
• Alters gene expression → protein synthesis starts
ex. anabolic steroids → effect protein synthesis → more actin + myosin → bigger muscles

Question 10

HYPOTHALAMUS

Answer 10

• Secretes releasing hormones (RH) and Inhibiting hormones (IH) → Pituitary gland stimulated
• Neurohormones = 2 “real” hormones secreted from hypothalamus: oxytocin and ADH (antidiuretic hormone)

Question 11

PITUITARY GLAND - Posterior

Answer 11

• Contains axons of cell bodies located in hypothalamus
• Does not synthesize hormones: just store and release neurohormones produced in hypothalamus
• Oxytocin: stimulates smooth muscle in mammary glands and uterus at child birth (not blood vessels → lack right receptors)
• ADH: decrease sweating and stimulate kidneys to retain water which decreases urine volume → decreases water loss; causes vasoconstriction in arteriols → increases blood pressure

Question 12

PITUITARY GLAND - Anterior

Answer 12

• Synthesizes hormones
• RH from hypothalamus → secretes hormone
• IH from hypothalamus → stops secretion
• Human growth hormone - hGH = stimulates protein synthesis in bones and muscles → normal growth
• Prolactin = stimulates milke production in breast feeding women
• Thyroid-stimulating hormone - TSH = activates thyroid gland
• Adrenocorticotropic hormone - ACTH = stimulates adrenal gland cortex
• FSH & LH = activates ovaries/testes (active in reproduction)

Question 13

THYROID GLAND

Answer 13

• Located below voice box (around wind pipe)
• Has a right and left lobe
• Stimulated by TSH → releases T3 and T4 → increases basal metabolic rate
• C-cells produces calcitonin → inhibits osteoclasts from breaking down bone → *decreases blood Ca2+ level → controlled by negative feedback

Question 14

PARATHYROID GLANDS

Answer 14

• Embedded in posterior part of thyroid gland → 4 of them → 2 (superior/inferior) in each thyroid lobe
• Increases blood Ca2+ levels by secreating parathyroid hormone -PTH

Question 15

ADRENAL GLANDS

Answer 15

• Located on top of each kidney
• 2 regions: Adrenal cortex and Adrenal medulla

Question 16

Adrenal cortex

Answer 16

• Outer region → 85% of the gland
• 3 zones synthesizing and secreting different steroid hormones
• Aldosterone (mineralocorticoid): secreted by outer layer; stimulates Na2+ uptake to blood and K+ excreation to urine
• Corticol (glucocorticoid): stimulated by ACTH and secreted by middle layer; regulates metabolism of carbonhydrates
• Androgens: stimulated by ACTH (mainly) and secreted by inner layer; stimulates development of gonads in the fetus

Question 17

Adrenal medulla

Answer 17

• Inner region of gland
• Consists of specialized postganglionic cells which secrete hormones adrenaline and noradrenaline
• Secretes during stres and exercise on command from preganglionic neurons in sympathetic ANS

Question 18

PANCREAS

Answer 18

• Located in curve of duodenum (tolvfingertarmen)
• Endocrine part: clusters of cells = pancreatic islets
• Secrete hormones regulated by current blood glucose level
• Insulin: Secreted by beta cells; promotes facilitated diffusion of glucose into cells and stimulate synthesis of glycogen from glucose and lipids → decreases blood sugar level
• Glucagon: secreted by alpha cells; stimulates formation of glucose from different sources; promotes breakdown of glycogen into glucose in the liver → glucose released into blood → increases blood sugar level

Question 19

Hormones

Answer 19

• Estrogen & progesterone = growth hormone stimulating protein synthesis in bones and muscles
• Testosterone = promotes movement of sperms (and same as above)
• Gastrin = promotes secretion of gastric juice and movements of stomach
• Secretin = stimulates secretion of pancreatic juice and bile
• CCK = cholecystokinin, stimulates secretion of pancreatic juice and brings feeling of fullness
• EPO = erythropoietin, increases production rate of red blood cells

Question 20

REPRODUCTIVE SYSTEM - Male

Answer 20

• LH stimulates production of testosterone
• FSH initiate development of sperm cells

Question 21

REPRODUCTIVE SYSTEM - Female

Answer 21

• FSH stimulates ovarian follicles to secrete estrogen
• LH stimulates secretion of estrogen and progesterone