Urinary System Flashcards
Diffusion
- Spreading of any particles in a solution.
- Moves from a high concentration to a low concentration on a concen. gradient
Osmosis
Movement of water through a semipermeable membrane down a concentration gradient.
- Dilute solution to concentrated solution.
Why is osmosis important?
Important for homeostasis to control water balance
Why is diffusion important?
Important for homeostasis for movement of substances
Ex: O2 into the blood and CO2 out
Active transport
-Uses energy to move substances against a concentration gradient across a semipermeable membrane.
- Transport in cells pick up particles and move them across the membrane
Why is active transport important?
Important in homeostasis in order to move substances into cells and moving glucose and sodium ions inside the kidneys
What are the functions of the kidneys? (4)
- Filtration: reabsorption, secretion
- Fluid balance: regulation
- Acid-base: balance regulation
- Hormone: production
List the upper urinary system
Two kidneys
Two ureters
List the lower urinary system
Urinary bladder
Urethra
Which kidney is more cranial?
The right kidney!
Glomerulus (“ball of yard” in Latin)
-“tuft” of capillaries
Function: Glom. capillaries filter some of the plasma out of the blood and put it in the capsular space of bowman’s capsule
Bowman’s capsule
Surrounds glomerulus
Urea
Nitrogen containing compound
polydipsia
Excessive thirst
Polyurea
Frequent urination
Urolithiasis
Stones in the urinary tract
Uremia
Excessive urea/nitrogen in the blood
Nephron
- Functional unit of the kidney
- Main goal is to processes waste from the blood to create urine
Proximal Convoluted Tubule (PCT)
Tubule NEAREST to the globulus
Production of urine:
Nephrons take wastes and toxins from the blood stream and turn it into urine to be expelled from the body.
Important substances for homeostasis
Sodium, potassium, calcium, magnesium, glucose, amino acids, chloride, bicarbonate, and water
What determines urine volume regulation?
Volume of water contained in the tubular filtrate when reaching the pelvis
What two hormones are responsible for the majority of urine vol regulation?
Two hormones:
1. Antidiuretic (released from posterior pituitary gland)
2. Aldosterone (secreted by adrenal cortex)
What is antidiuretic (ADH) role in urine vol regulation?
Hint: without it, there would be polyuria
Acts on the DCT/collecting ducts to promote water reabsorption and prevent water loss from the body.
Distal Convoluted Tubule (DCT)
- Continuation of the ascending loop of Henle
- Empties into the collecting ducts
Loop of Henle:
Location and function
- Location: Descends from PCT into medulla, turns, heads upward into the cortex
- Function: At the bottom loop, epithelial cells flatten to simple squamous cells and lose their brush border
Renal corpuscle’s location and function
- Location: Renal cortex
- Function: Filters blood in the first stage of urine production
Peritubular capillaries
Converge to form venules, then larger veins, and finally the renal vein
Renal vein
Leaves the kidney at the hilus
List the main blood vessels associated with the kidneys (4)
- Right renal vein
- Right renal artery
- Left renal vein
- Left renal artery
Urinary bladder structure and function
- Structure: Lined with transitional epithelium that stretches as the bladder becomes filled with urine. Walls contain smooth muscle bundles. Neck of bladder extends caudally from the sac into the pelvic canal & joins the urethra. Neck of urinary are circular muscles of skeletal muscle fibers
- Function: Controls urination
Ureters structure and function
- Structure: Leave kidneys at hilus. Outer fibrous layer, middle smooth muscle, and inner layer lined with transitional epithelium.
- Function: Smooth muscle propels urine through ureter by peristaltic contractions
Micturition (simplified)
Expulsion of urine from the urinary bladder into the urethra
The control of urine (micturition process)
- Urine accumulates until pressure of the filling bladder activates stretch receptors in bladder wall
- Spinal reflex returns a motor impulse to bladder muscles causing them to contract
- Contraction gives the sensation to urinate - Voluntary control of the muscle sphincter around the neck of the bladder results in temp control of urination
Urethra structure and function
- Structure: Continuation of the neck of the urinary bladder. Lined with transitional epithelium which allows it to expand.
- Function: Carries the urine from the bladder to the external environment.
Male vs female urethras
- Male: Urethra runs down the center of the penis and functions in the reproductive system.
- Female: Urethra (shorter than the male’s) opens on the ventral portion of the vestibule of the vulva
Production of urination
- Blood is forced into the glomerulus, then into the bowman capsule (filtrate).
- PCT: Salt, glucose, Ka+, bicarbon, and water are reabsorbed.
- H+ & ammonium are secreted into prox tube.
- Descending loop: water will move to the hypertonic interstitial fluid.
- Ascending loop: NaCl can diffuse out in thin, then use active transport in the thick portion.
- DCT: H+ ammonium, Ka+ secreted back in. NaCl, water, bicarb reabsorbed.
- Collecting duct: Hormones will control the amount of fluids reabsorbed and the rest will be urine!
What is commonly in filtrate? (blood after it passes the Bowmans capsule)
- Salt
- Water
- Glucose
- Amino Acids
- Bicarbonate ions
- H+
- UREA!
- (sometimes) Medications
