Urinary / Renal System Flashcards
Kidney Functions:
Regulates water volume, concentrations, and pH levels
Influences red blood cell production and blood pressure
Continuously filter blood; hold 20% of blood volume at any given time
Retroperitoneal
Kidneys lie between the dorsal wall and the peritoneum
Kidney layers
Renal cortex
Renal medulla
Renal pelvis
Renal cortex
Outermost cortex
Renal medulla
A set of cone-shaped masses of tissue that secrete urine into tiny sac-like tubules
Renal pelvis
A funnel-shaped tube surrounded by smooth muscle that uses peristalsis to move urine out of the kidney, into the ureter, and to the bladder.
Nephron
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
- Filtration
- Collection
- Excretion
Nephron structures
Renal corpuscle- contains glomerular capsule
Glomerular capsule- also called Bowman’s capsule
Glomerulus- inside the glomerular capsule and looks like a ball of yarn
Renal tubule
Vasa recta- peritubular capillaries where blood cells and proteins exit to stay in the blood
Filtrate
Everything squeezed out of the blood into the glomerulus
Renal tubule parts
- Proximal convoluted tubule (PCT)
- Nephron loop (loop of Henle)
- Distal convoluted tubule (DCT)
- Collecting duct
Long and curvy structure of the renal tubule allows for
Tubular reabsorption
The loop is long to provide more time for reabsorption to occur
Urea
Necessary for the kidneys to ramp up the concentration gradient earlier in the process, making the medulla even saltier (higher osmolarity) for the filtrate that’s going through the ascending limb
The salt passively draws out more water from the collecting duct
Tubular secretion
Actively transports select kinds of wastes that have already made their way into the blood that’s in the peritubular capillaries, ready to leave the kidneys.
Urination
Removes toxins to help maintain water-volume homeostasis, or blood pressure
Urine contains
95% water
5% solutes
Normal urinalysis
pH 6: slightly acidic
clear/yellow in color depending on hydration status
Leukocytes
Pyuria- leukocytes in the urine
Indicates urinary tract infection (UTI)
Glucose
Glycosuria- glucose in the urine
Indicates diabetes mellitus
Erythrocytes
Hematuria- erythrocytes or red blood cells in the urine
Indicates bleeding in the urinary tract
Proteins
Proteinuria, albuminuria- proteins in the urine
Indicates excessive exercise, pregnancy, high blood pressure, heart failure, or severe hypertension
Glomerular filtration rate
The amount of blood that passes through the glomeruli every minute
Autoregulation
Intrinsic control of the filtration rate through normal ranges of blood pressures
ADH
Antidiuretic hormone secreted by the posterior pituitary gland to help the body retain water and stay hydrated.
Move aquaporins from basal side to apical side which allows more water to leave the urine and allow for more water reabsorption.
Inhibited by caffeine and alcohol
Bladder
Hollow, collapsible sac that temporarily holds urine
Ureters
Pair of slender tubes that drop down to the posterior urinary bladder
Contain smooth muscle that contracts to move urine using peristalsis
Bladder wall
Inner mucosa- contains transitional epithelium which allows the bladder to expand so it can hold more urine
Detrusor- thick muscular layer
Outer membrane- fibrous protective layer
External urethral sphincter
Made of skeletal muscles and controlled voluntarily
Urination
Parasympathetic neurons are stimulated while sympathetic system is inhibited
- The detrusor contracts
- The internal urethral sphincter opens
- The external urethral sphincter opens
Pontine storage area (in the pons in the brain)
Inhibits urination
Pontine micturation center (in the pons in the brain)
Stimulates / activates urination
Kidneys have
2 capillary beds which connect the arteries to the veins
- Vasa recta- gives oxygen to the kidneys
- Peritubular capillaries- collecting nutrients that the kidneys will filter out
Blood enters the kidneys through the
Renal artery
Renal veins
Take what is reabsorbed by the kidneys and bring it back to the blood
Nephron
Single functional unit of the kidneys
Functional unit in filtration and collection
Sits between the renal cortex and the renal medulla
Renal calyx
First part of the kidneys where urine is present
Renal pelvis
Collects the urine from all the renal calyces
Kidneys maintain homeostasis
Maintains pH by regulating hydrogen ions
Maintains BP by regulating sodium and chloride ions
Maintains osmolarity
Secretes waste products, such as urea
Bowman’s capsule
Collects the filtrate from the glomerulus
Podocytes
Specialized epithelial cells only seen at the glomerulus; have lots of branches that intertwine; form the visceral layer of the glomerular capsule
Glomerular capillaries
Have fenestration slits / pores which help filter the blood when it flows through the capillaries.
Glomerular capillaries have a filtration membrane
Female urethra
The female urethra is much shorter than the male urethra which is why women get more UTIs
Renal blood flow is autoregulated
Autoregulation- locally controlled blood flow despite fluctuating blood pressure.
Erythropoietin
Renal hormone that stimulates RBC production in response to hypoxia
Vitamin D
Renal hormone that activates the kidneys (Ca and PO4 balance)
Ureters
30 cm long
Long, intertwining muscle bundles
Pass obliquely through posterior aspect of bladder
Peristaltic activity
Micturation compresses the lower end of the ureter to avoid urine reflux
