Unit 11 Review

Unit 11 Review: ● ● ● ● ● List the components of the urinary system and their general functions ○ Kidneys: removes waste products from the blood and produces urine ○ Ureters: attached to the kidneys, moves the urine into the urinary bladder ○ Urinary bladder: temporarily stores urine until excretion ○ Urethra: moves the urine out of the body during micturation Describe the location of the kidneys and the gross anatomy of a kidney ○ Each kidney is lined with a fibrous outer capsule that covers the renal cortex of each kidney. Below the renal cortex is the renal medulla that is divided into renal pyramids. Describe the structure of a nephron ○ The nephron is made of a renal corpuscle (glomerulus inside the glomerular capsule) and renal tubule (PCT, nephron loop, and DCT) ○ Glomerulus: contains about 50 intertwined capillaries inside the bowman's capsule supplied by an afferent arteriole and removed through an efferent arteriole. They are fenestrated capillaries with a filtration membrane that pushes out filtrate through hydrostatic pressure ○ Renal tubule: once the filtrate enters the PCT of the renal tubule it is called tubular fluid ■ PCT: major reabsorption of water, ions, and nutrients from the filtrate ■ Descending loop: water passively leaves the tubular fluid, but it is impermeable to ions ■ Ascending loop: Cl- and Na+ passively leave and the loop is impermeable to water ■ DCT/Collecting duct: fine tunes the final composition of urine by reabsorbing any other ions/water and regulates Na+ and K+ Describe the blood supply to the kidney ○ Blood is delivered by the afferent arteriole that enters the glomerular capillaries and leaves through the efferent arteriole Describe the location and gross anatomy of the ureters, urinary bladder and urethra ○ Ureters ■ Ureters are muscular tubes that deliver urine from the kidneys through the hilum and empty it into the urinary bladder ■ The enter the urinary bladders through the back through a small slit that stops the backflow of urine ○ Urinary bladder ■ Temporarily stores urine before excretion ■ Rugae allow for expansion (transitional epithelium) ■ Detrusor muscle squeezes the bladder during contraction ■ Trigone area acts as a funnel for urine into the urethra ■ Internal involuntary sphincter and external voluntary sphincter ○ Urethra ■ Carries urine from the bladder out of the body, is longer in males ● ● ● ● ● ● Outline the general characteristics of the following processes: glomerular filtration, tubular reabsorption, and tubular secretion ○ Glomerular filtration: blood plasma is forced through pores of the filtration membrane (hydrostatic pressure) and small molecules that pass through are carried along to form filtrate ○ Tubular reabsorption: returns nutrients from the tubular fluid to the blood through diffusion, osmosis, channel-mediated diffusion, and carrier-mediated transport ○ Tubular secretion: removes substances from the blood and adds it to the tubular fluid like H+, K+, and organic ions (K+ or H+ is secreted in exchange for Na reabsorption to maintain concentration gradients) Define the term “Glomerular Filtration Rate” and explain how glomerular filtration rate is measured, the nature of the glomerular filtrate, and the factors that affect filtration rate ○ Glomerular filtration rate: the amount of filtrate the kidneys produce in 1 minute ■ High creatinine levels indicate reduce GFR and reduced kidney function ■ Glomerular filtrate has similar composition to plasma until it enters the renal tubule and the composition is changed ■ GFR is controlled by autoregulation (vasoconstriction/dilation), hormonal regulation (RAAS and natriuretic peptides), and autonomic regulation (SNS stimulation can cause powerful vasoconstriction that reduces GFR) Describe how specific segments of the renal tubules and collecting ducts reabsorb water and solutes ○ PCT: major reabsorption of water, ions, and nutrients from the filtrate ○ Descending loop: water passively leaves the tubular fluid, but it is impermeable to ions ○ Ascending loop: Cl- and Na+ passively leave and the loop is impermeable to water ○ DCT/Collecting duct: fine tunes the final composition of urine by reabsorbing any other ions/water and regulates Na+ and K+ Describe the mechanism of countercurrent multiplication on nephron function and explain how it helps concentrate urine, explain how dilute urine is formed ○ Countercurrent multiplication occurs in the ascending and descending nephron loops (because of their opposing impermeabilities) and the vasa recta ○ Dilute urine is formed though: ■ Decreased permeability of water in the collecting ducts ■ Less fluid is reabsorbed from the interstitial fluid into the tubular fluid ■ Reduced amounts of ADH Define the term renal plasma clearance, and explain how it can be applied to determine the GFR ○ Renal plasma clearance: a measure to assess the efficiency of the kidneys in removing substances from the blood plasma ○ The amount of creatinine calculated from this test can be used to identify kidney filtration/function and GFR Clinical applications: ○ ○ Discuss the causes and clinical features of renal failure ■ Renal failure is when your kidneys no longer function properly Explain the general principle and purpose of renal dialysis ■ Dialysis is used when your kidneys no longer function properly, and you need a device to filter your blood for you and remove urea and other wastes ■ Hemodialysis: the blood is cleaned outside of the body and goes through the device before returning to the body ■ Peritoneal dialysis: a device is inserted into the body to continuously filter blood