Urinary I Flashcards
What are the four major organs of the urinary system?
Kidneys
Ureters
Urinary bladder
Urethra
What are the three main functions of the urinary system? How does the urinary system accomplish this?
- Excretion
- Micturition
- Homeostatic regulation of plasma chemistry
How: filters blood plasma, returns most water & solutes to bloodstream, excretes water and solutes in urine as waste, bladder stores urine until voiding
What are the functions of the kidney? What are the 1 million functional units of the kidney?
Regulation of blood ionic composition, refulation of blood pH, regulation of blood volume, regulation of bp, maintenance of blood osmolarity, production of hormones, excretion of metabolic wastes and foreign substances, regulation of BGL
Nephrons
What is a nephron composed of? What are the basic processes of a nephron. Be able to describe the three basic processes occurring in the nephron in terms of urine formation.
Renal corpuscles, renal tubules, collecting ducts, papillary ducts
1. Glomerular filtration: movement of fluid from blood plasma across filtration membrain into nephron tubule where it becomes 1st filtrate and then tubular fluid, this is an indiscrimainate process occurring only in the glommerulus
2. Tubular reabsorption: movement of water and certain solutes from tubular fluid in the nephron to peritubular fluid and then into the blood, this occurs throughout the nephron tubule w/ varying degrees of specificity
3. Tubular secretion: movement of solutes from blood to peritubular fluid to tubular fluid for excretion
Be able to trace the flow of fluid (filtrate) through the nephron as urine forms.
renal corpuscle- proximal convoluted tubule- descending limb of loop of Henle- ascending limb of loop of Henle- distal convoluted tubule- collecting duct- papillary duct
Be able to describe the two types of nephrons in terms of location and function.
Cortical nephron: 80-85% of nephrons, renal corpuscle in outer portion of cortex, create urine w/ osmolarity similar to blood, bulk of excretion associated with peritubular capillaries
Juxtamedullary nephron: renal corpuscle deep in cortex along nephron loops, enables kidney to secrete very ocncentrated urine (maintains osmotic balance of blood)
Be able to describe the function of the juxtaglomerular apparatus
regulates bp in kidney in conjuction w/ ANS
Be able to explain glomerular filtration.
Driven by bp, opposed by capsular hydrostatic pressure and blood colloid osmotic pressure, water and small molecules move out of glomerulus, 150-180 L of water pass out into glomerular capsule/day, glomerular filtration rate (GFR)- amount of filtrate formed by both kdineys/min, homeostasis requires kidneys to maintain a relatively constant GFR- too high-substances pass to quickly and not reabsorbed - too low-nearly all reabsorbed and some waste products not adequately excreted
What are the three components of the filtration membrane in the renal corpuscle. Be able to describe the glomerular filtration membrane in terms of structures and function. Understand how pressure in the glomerulus forms urine without stealing blood. Know the pressures that govern the rate of flow from the blood.
- fenestrations-stops all cells and platelets
- basement membrane-stops large plasma proteins
- podocytes-stops medium sized proteins
Blood goes through larger afferent arteriole then exits smaller efferent arteriole automatically creating pressure that drives fluids and plasma out of glomerulus into capsular space of renal corpuscle
Glomerular Hydorstatic Pressure
Know 8 components of glomerular filtrate
H2O, Na+, Cl-, Ca2+, K+, glucose, uric acid, urea, ammonia, H+, PO4-, NO3-, urobilin
Know and be able to explain the regulatory mechanisms for glomerular filtration rate (GFR)
renal autoregulation
neural regulation
hormonal regulation
Renal Autoregulation: myogenic mechanism (smooth msucle cells in afferent arterioles contract in response to elevated bp), tubuloglomerular feedback (Macula densa cells of JGA detect blood as salty, JGA can causes decrease in nitric oxide- vasoconstriciton, afferent artioles constrict decreasing blood flow through glomerulus, reduce GFR)
Neural Regulation: sympathetic ANS, constrict afferetn arterioles to reduce GFR, shunts more blood volume to core, reduce blood in kidneys, decreases GFR
Hormonal Regulation: stimulated by decrease in BP at glomerulus, sympathetic stimulation of JGA, causes release of ADH, Aldosterone, Angiotensin, Renin, ANP
Know and be able to explain the renin-angiotensin-aldosterone pathway. Understand how this pathway and ADH and ANP assists in maintaining blood volume and blood pressure in homeostasis.
dehydration,Na+, hemorrhage-decrease blood volume-decrease bp-Renin-angiotensin I-ACE-angiotensin II-stimulates thrist centers in hypothalamus
(aldosterone after angiotensin)
Stimulates thirst signal, ANP only mechanism in body to lower BP, puts more water in urine,
