Unit 5 Flashcards
What is the function of the urinary system?
to filter blood and produce urine which allows us to maintain fluid and electrolyte balances
What are the 4 components of the urinary system?
- kidneys: process blood, 2
- ureters: passageway from kidney to bladder, 2
- urinary bladder: where urine gets stored
- urethra: exit pathway of urinary system
What are 8 functions of the urinary system?
- fluid filtration
- regulate blood volume
- maintains salt/water balance
- maintains acid/base balance
- gluconeogenesis
- renin production
- erythropoietin production
- activates vitamin D
What are 10 parts of the kidney structure?
- capsule: outer portion
- cortex: outer region of kidney
- medulla: deep to cortex
- pelvis: hollowed out region that collects fluid and connects to ureter
- sinus: space in pelvis that holds fluid
- hilum: indentation where ureter attaches
- pyramids: triangle shaped structures in medulla that contain collecting tubules
- columns: b/w pyramids, internal projections of cortex tissue
- major calyces: minor merge together to form these
- minor calyces: renal pyramids collecting tubules empty into this structure
What are the 3 supportive layers of the kidney?
- renal capsule: tissue surrounding kidney & holds it together
- adipose tissue: surround kidney to cushion, insulate, and protect kidney
- renal fascia: anchors kidney to rear wall of abdominal cavity
What is a nephron?
functional unit of kidney and make up most of the structure of the kidney
What are the components of the nephron?
- glomerulus: fenestrated capillary
- renal tubule: contains Bowman/s capsule, proximal convoluted tubule, loop of Henle, & distal convoluted tube
- Glomerular (Bowman’s) capsule: tube that completely surrounds the glomerulus
- proximal convoluted tube: close to glomerulus and connects to descending loop of Henle
- Loop of Henle: contains an ascending and descending portion
- Distal convoluted tube: further from glomerulus and connects to collecting tube
- collecting ducts: connect to many renal tubules and ultimately to a ureter
- renal corpuscle: bowman’s capsule + glomerulus
What are two types of nephrons?
- cortical: majority, most of nephron located in cortex and small portion of loop of Henle extends to medulla
- juxtamedullary: closer to medulla and loop of Henle descends farther into medulla, concentrates the urine more
What are 4 parts of nephron vasculature?
- afferent arteriole: delivers blood to glomerular capillaries
- efferent arteriole: exits glomerulus
- glomerulus: fenestrated capillary
- peritubular capillaries: surround renal tubule in cortical nephrons
- vasa recta: peritubular capillaries in medulla found in juxtamedullary nephrons
What is the juxtaglomerular apparatus?
modification where distal convoluted tubule runs against afferent arteriole
What are the two modification of the juxtaglomerular apparatus?
- smooth muscle of afferent arteriole wall: changes to juxtaglomerular cells which act as mechanoreceptors which monitor pressure of blood which activates these cells to produce renin
- epithelium of distal convoluted tubule: changes to macula densa cells which function as chemoreceptors and monitor concentration of filtrate and can activate JG cells to secrete renin
What occurs to plasma in the tubule?
plasma enters -> becomes filtrate -> becomes urine in collecting ducts
What makes up the filtration membrane of the glomerulus?
- fenestrated epithelium: allows everything to pass except cellular components
- podocytes: surround basement membrane and have extensions called pedicels; reduce SA for exchange and create filtration slits b/w pedicels
- basement membrane: surrounds capillaries and prevents proteins from passing through while also creating an electrical gradient
What are 3 processes or urine formation?
- filtration: passive & nonselective; occurs at glomerulus and becomes filtrate
- tubular reabsorption: active or passive; modify filtrate by resorbing things out of tubule into bloodstream; occurs along tubule and proximal collecting duct
- tubular secretion: active or passive; modify filtrate by secreting things into tubule; occurs along tubule and proximal collecting duct
What are the 4 steps of urine formation?
- Blood arrives at glomerulus & through process of filtration we get filtrate that enter tubule
- Filtrate contains all plasma components except for proteins
- Tubular resorption & secretion occur
- After filtrate is modified through these processes, it becomes urine
What are 4 types of filtration pressure?
- glomerular hydrostatic pressure: pressure inside glomerulus, simply BP
- colloid osmotic pressure of intracapsular space: in bowman’s capsule, should be 0
- colloid osmotic pressure of glomerular blood: pressure created from proteins in the glomerular capillaries, wants to draw things back in
- capsular hydrostatic pressure: pressure outside capillary in bowman’s capsule, lower than GHP, limits exchange
what is the driving force of filtration?
glomerular hydrostatic pressure
What affects GFR (glomerular filtration rate) and RBF (renal blood flow)?
- dilation of afferent: increased RBF and GFR
- constriction of afferent: decreased RBF and GFR
- dilation of efferent: increased RBF and decreased GFR
- constriction of efferent: decreased RBF and increased GFR
What is different abt the glomerular capillary compared to other capillaries?
- higher pressure than most capillaries
- fenestrated epithelium
- located b/w two arterioles
What do we usually resorb back into the bloodstream from filtrate?
- almost all glucose and amino acids
- some water and ions
where does most tubular secretion occur?
proximal convoluted tubule
What are two limiting factors of filtration?
- amount of net filtration
- podocytes have pedicels which form slits that reduce SA
What are 4 mechanisms of filtration regulation?
- myogenic mechanism: intrinsic; low BP causes dilation of smooth muscle and afferent arteriole which increase filtration & vice versa
- tubular glomerular mechanism: intrinsic; macula densa cells cause vasodilation of afferent arteriole if dilute filtrate or low osmolarity & vice versa; also activate JG
- hormonal mechanism: extrinsic or intrinsic (macula densa or neural mechanism); low BP causes JG cells to release renin causes systemic vasoconstriction, increase in Na+ resorption, and adrenal cortex to secrete aldosterone
- neural control: extrinsic; override mechanism that uses sympathetic impulses and NE to cause vasoconstriction of afferent arteriole which causes increased BP and filtration
What are 4 other factors that affect filtration?
- prostaglandins: local signaling molecules that act as vasodilators and fine tune our neural and hormonal signals
- nitric oxide: vasodilator
- adenosine: vasoconstrictor in kidneys
- endothelin: released by blood vessels and acts as a vasoconstrictor