Excretory System Flashcards
what is homeostasis? what are the 3 factors of homeostasis?
maintaining a constant internal environment despite changes, water balance, temp, pH (excretion is the process of removing metabolic wastes
what are the 3 functions of the excretory system?
excretion of metabolic wastes, maintaining water balance (osmoregulation, water/salt levels in the blood), regulation of blood pH
what are the structures and functions of the renal system?
2 kidneys (filter blood), 2 ureters (transport urine from kidneys to bladder), urinary bladder (stores urine), urethra (bladder to environment)
what are the 3 distinct regions of the kidney?
cortex, medulla, pelvis
where does filtration, reabsorption, secretion and elimination occur?
filtration (glomerulus and bowman’s capsule)
reabsorption (proximal tubule, loop of henle, distal tubule, collecting duct, peritubular capillary net (blood))
secretion (distal tubule)
elimination (urethra to environment)
what happens in filtration?
glomerulus: high pressure capillary bed
bowman’s capsule: double walled chamber, beginning of nephron
blood goes into glomerulus (afferent arteriole) and leaves (efferent), nephric filtrate (solution that passes through filter into bowman’s capsule)
small pores form a filter that only allow small materials to move from blood plasma to bowman’s capsule
what happens in reabsorption?
nephron tubule (proximal tubule, loops of henle, distal tubule, collecting duct) to peritubular capillary net (blood) most filtrate is reabsorbed back into blood, homeostasis of blood contents osmolarity (amount of solutes) adjusted by reabsorption of salts and water (most reabsorbed), glucose, amino acids peritubular; blood from efferent art feed into peri cap, wrap around nephron, reabsorption occurs when substances move into these capillaries, capillaries eventually lead into renal vein as clan blood
what happens in secretion?
peritubular capillary back to nephron tubule, occurs in distal tubule ACTIVE TRANSPORT (requires ATP, high # mitochondria in nephron cells), solutes secreted includes H ions to regulate pH and K ions for muscle and nerve control, antibiotics and drugs
what happens in elimination?
nephric filtrate passes into collecting duct, then renal pelvis and is considered urine (bladder), eliminated through urethra
what is the order of urine formation?
blood, nephron, collecting duct, renal pelvis, ureter, bladder, urethra, environment
where does most water reabsorption occur?
loop of henle
where does regulation of pH of blood through secretion of H ions occur?
distal tubule, aldosterone turns on Na reabsorption
where is last chance for water reabsorption?
collecting duct, ADH controls water reabsorption by increasing permeability of membrane
what are the 2 hormones of the excretory system?
antidiuretic hormones (ADH): pituitary gland, increases permeability of collecting ducts to water used when dehydrated, decreased volume of urine produced, increased concentration aldosterone: adrenal gland, turns on Na pump in distal tubule, causes Na reabsorption into the blood (water follows), used to INCREASE BLOOD PRESSURE, decrease volume of urine produced, increase concentration
what happens where there is high Na in blood? Low Na?
osmosis, cells lose water and shrink (hypertonic), salty urine
cells grow, become hypotonic, decrease ADH, decrease water reabsorption
