Chapter 10- Homeostasis Flashcards
excretory system
regulating blood pressure, blood osmolarity, acid-base balance, removal of nitrogenous wastes
anatomy of excretory system (in order)
kidneys, ureters, bladder, urethra
kidney
filters blood to form urine. Regulates blood volume and osmolarity. made up of: cortex (outermost layer) and medulla (within the cortex)
glomeruli
highly convoluted capillary tufts derived from afferent arterioles
vasa recta
capillaries that surround loop of Henle
detrusor muscle
lining of bladder. parasympathetic activity causes contraction.
internal and external urethral sphincter
internal- smooth muscle (involuntary muscle)
external- skeletal muscle (voluntary muscle)
micturition reflex
full bladder causes stretch receptors to tell nervous system (parasympathetic) to contract detrusor muscle. this contraction causes the internal sphincter to relax
3 processes involved in kidney function
- filtration (movement of solutes from blood to filtrate at Bowmans capsule)
- secretion (movement of solutes from blood to filtrate anywhere besides Bowmans capsule)
- absorption (movement of solutes from filtrate to blood)
filtrate
collected fluid after it has passed through glomerulus/ bowmans space
starling forces
governs movement of fluid into bowmans space. accounts for different pressure (higher P in glomerulus, so fluid will move into the nephron)
if blood or protein is found in the urine, what does that indicate?
health problem at level of glomerulus in the kidney
liver converts ammonia to…?
urea, which travels to kidney and is secreted into nephron for excretion with urine.
what compounds are almost always reabsorbed?
glucose, amino acids, and vitamins (water depending on levels of ADH)
parts of the nephron
- proximal convoluted tube
- loop of henle
- distal convoluted tube
- collecting duct
proximal convoluted tube
controls solute identity. reabsorbing vitamins, amino acids, and glucose. while secreting K, H, ammonia, and urea
interstitium
connective tissue surrounding the nephron. solutes that enter this are picked up by the vasa recta to be returned to the bloodstream for reuse within the body.
2 parts of loop of henle
- descending limb (permeable only to water, using medullary concentration gradient)
- ascending limb (permeable only to salts)
countercurrent multiplier system
created by the vasa recta and nephron. flow of filtrate through loop of Henle is in opposite direction from flow of blood through vasa recta. the filtrate is then constantly being exposed to hypertonic blood which allows for maximal reabsorption of water.
diluting segment of loop of henle
at transition from inner to outer medulla, the loop of henle becomes thicker (cells lining tube are larger)
distal convoluted tube
important for solute identity by reabsorbing salts while secreting K, H, ammonia, and urea.
collecting duct
responsive to both aldosterone and ADH/vasopressin. permeability will depend on how hydrated the person is. point of no return (if it doesnt leave here then it will be excreted from the body)
2 important hormones for maintenance of blood pressure
aldosterone and ADH/vasopressin
aldosterone
steroid hormone secreted by adrenal cortex in response to decreased blood pressure. alters ability of distal convoluted tubule and collecting duct to reabsorb sodium thus water will follow to increase bp.
cascade to stimulate aldosterone release
decreased bp stimulates release of renin from juxtaglomerular cells in kidney. Renin cleaves angiotensinogen (liver protein) to form angiotensin I then metabolized to form angiotensin II which promotes the release of aldosterone from adrenal cortex.
Antidiuretic hormone (ADH/ vasopressin)
peptide hormone synthesized by hypothalamus and released by the posterior pituitary in response to high blood osmolarity. alters permeability of collecting duct. allowing more water to be reabsorbed by making cell junctions of duct leaky. (ONLY WATER, so result is decreased blood osmolarity)
what inhibits ADH release?
alcohol and caffeine. causes frequent excretion of dilute urine.
osmotic vs oncotic pressure
osmotic- “sucking” pressure drawing water into vasculature caused by dissolved particles
oncotic- osmotic pressure attributable to dissolved proteins specifically
when blood osmolartiy is low vs. high
low- excess water will be excreted
high- water will be absorbed (more solutes will be excreted)
when blood pH is too low…
kidneys excrete more hydrogen ions and increase reabsorption of bicarbonate, resulting in higher pH
when blood pH is too high…
kidneys can excrete more bicarbonate and increase reabsorption of hydrogen ions, resulting in lower pH
vessels in renal vascular pathway
renal artery, afferent arteriole, glomerulus, efferent arteriole, vasa recta, renal vein
bowmans capsule
site of filtration (for size). water, ions, amino acids, vitamins, and glucose pass
3 layers of skin (deepest to most superficial)
- hypodermis (subcutaneous layer)
- dermis
- epidermis
* skin is derived from ectoderm
epidermis (and its 5 layers in order from deepest to most superficial)
outer-most layer of skin. subdivided into strata.
- basale (stem cells/ proliferation of keratinocytes which produce keratin)
- spinosum (site of langerhans cells, connectedness here)
- granulosum (keratinocytes die and lose nuclei)
- lucidum (only present in thick, hairless skin)
- corneum (contains 3 dozen layers of flattened keratinocyes for protection)
* in opposite order: Come Lets Get Sun Burned*
keratin
resistant to damage and provides protection against injury, water, and pathogens.
calluses
form excessive keratin deposition in areas of repeated strain due to friction.
melanocytes
cell type derived from neural crest cells and found in stratum basale. produce melanin to give pigment to skin.
langerhans cells
special macrophages that reside within stratum spinosum. capable of presenting antigens to T-cells in order to activate immune system
Dermis (with its multiple layers)
superficial to deep
papillary layer- loose connective tissue
reticular layer- sweat glands, blood vessels, hair follicles originate here
most sensory cells are also in dermis.
hypodermis
connective tissue that connects the skin to the rest of the body. this layer contains fat and connective tissue.
4 mechanisms for thermoregulation by skin
- sweating (cooling mechanism due to evaporation of sweat from skin by autonomic NS)
- piloerection (heating mechanism caused by arrector pili muscles to trap a layer of heated air near skin)
- vasodilation (cooling)
- vasoconstriction (heating)
white fat vs. brown fat
white- helps to insulate body
brown- much less efficient ETC which means more heat energy is released as fuel is burned (especially in infants)
skin permeability
skin is relatively impermeable to water
passage of blood through vessels of kidney
renal artery, afferent arterioles, glomerulus, efferent arterioles, vasa recta, renal vein
