Homeostasis Flashcards
serves many functions, including the regulation of blood pressure, blood osmolarity, acid-base balance, and removal of nitrogenous wastes
excretory system
flow of urine
has a muscular lining known as the detrusor muscle, which is under parasympathetic control; has two muscular sphincters
bladder
bladder:
consists of smooth muscle and is under involuntary (parasympathetic) control
internal urethral sphincter
bladder:
consists of skeletal muscle and is under voluntary (sympathetic ) control
external urethral sphincter
contains a cortex (outer portion) and a medulla (inner portion), and has a hilum which contains a renal artery, renal vein, and ureter; produces urine, contains a portal system, participates in solute movement, functional unit is the nephron, is under hormonal control and can regulate pH
kidney
kidney:
has two capillary beds in series in the kidney; blood from renal artery flows through afferent arterioles, which form glomeruli in Bowman’s capsule (the first capillary bed); blood then flows through efferent arteriole to the vasa recta (the second capillary bed), which surround the nephron; blood leaves the kidney through the renal vein
renal portal system
kidney:
kidney function of regulating blood volume and osmolarity; occurs through three processes in the kidney
solute movement
solute movement:
the movement of solutes from blood to filtrate at Bowman’s capsule; the direction and rate is determined by Starling forces which account for the hydrostatic and oncotic pressure differentials between the glomerulus and Bowman’s space
filtration
solute movement:
the movement of solutes from blood to filtrate anywhere other than Bowman’s capsule
secretion
solute movement:
the movement of solutes from filtrate to blood
reabsorption
kidney:
functional unit of the kidney, about a million of them; has five segments each with specific function
nephron
nephron:
first part of nephron where blood is initially filtered to form filtrate
Bowman’s capsule
nephron:
a network of small blood vessels (capillaries), known as a tuft, that prevents entry of large molecules, such as proteins, into filtrate
glomerulus
nephron:
the site of bulk reabsorption of glucose, amino acids, soluble vitamins, salt, and water; also site of secretion for hydrogen ions (H+), urea, ammonia (NH3), and potassium ions (K+)
proximal convoluted tube (PCT)
proximal convoluted tube (PCT) mnemonic
dump the HUNK:
H (H+ ions), U (urea), N (NH3), K (K+ ions)
nephron:
permeable to water but not salt; therefore, as the filtrate moves into the more osmotically concentrated renal medulla, water is reabsorbed from the filtrate; the vasa recta and nephron flow in opposite directions, creating a countercurrent multiplier system that allows maximal reabsorption of water
descending limb of the loop of Henle
nephron:
permeable to salt but not water; therefore, salt is reabsorbed both passively and actively; the diluting segment is in the outer medulla; because salt is actively reabsorbed in this site, the filtrate actually becomes hypotonic compared to the blood
ascending limb of the loop of Henle
nephron:
is responsive to aldosterone and is a site of salt reabsorption and waste product excretion
distal convoluted tube (DCT)
nephron:
is responsive to both aldosterone and antidiuretic hormone (ADH or vasopressin) and has variable permeability, which allows reabsorption of the right amount of water depending on the body’s needs
collecting duct
kidney:
control the kidney; when blood pressure (and volume) are low, two different ____ systems are activated
hormones (hormonal)
hormone:
a steroid hormone regulated by the renin-angiotensin-____ system that increases sodium reabsorption in the distal convoluted tubule and collecting duct, thereby increasing water reabsorption; results in an increased blood volume (and pressure), but no change in blood osmolarity
aldosterone
hormone:
a peptide hormone synthesized by the hypothalamus and released by the posterior pituitary; its release is stimulated not only by low blood volume but also by high blood osmolarity; it increases the permeability of the collecting duct to water, increasing water reabsorption; results in an increased blood volume (and pressure) and decreased blood osmolarity
antidiuretic hormone (ADH or vasopressin)
kidney:
kidney function by selective reabsorption or secretion of bicarbonate (HCO3-) or hydrogen ions (H+)
pH regulation
