Ch. 17 Urinary System

Functions of urinary system

• remove salts and nitrogenous wastes

• maintain normal concentrations of water and electrolytes

• regulate pH volume of body fluids

• help control RBC productions and blood pressure

shape and location of kidneys

• lateral surface is convex

• medial side is concave

• its in the mid-abdomen area

renal capsule

most superficial on the kidney

renal cortex

next layer in the kidney and is around the medulla and includes the renal columns which go in between the renal pyramids

renal medulla

deepest layer in the kidney and contains the renal pyramids

what is the hilum

the entrance to the renal sinus, the depression on the medial side for vessels to enter/exit

what is the renal pelvis

the funnel shaped end of the ureter inside the renal sinus

minor calyx

smaller tubes that lead from the renal papillae to the major calyx

major calyx

large tubes that lead from the minor calyces to the renal pelvis

specific functions of the kidney

• removes wastes from blood

• mix it with water and electrolytes to produce urine

• secrete erythropoietin

• active vitamin D

• use the enzyme renin to help control volume of fluids and blood pressure

flow of blood through the kidneys

renal artery, interloper artery, arcuate artery, interlobular artery, afferent arteriole, glomerulus, efferent arteriole, peritubular capillaries, interlobular veins, arcuate veins, interlobar veins, renal vein, inferior vena cava

what is a nephron?

main filtering apparatus of the kidney, there are about 1 million per kidney

formation of urine through the renal tubule

glomerular capsule, continues in the proximal convoluted tubule, descending limb, ascending limb, distal convoluted tubule, collecting duct, renal papillae, minor calyx, major calyx, renal pelvis, ureter, urinary bladder, urethra

why is the diameter of the efferent and afferent arterioles important to glomerular filtration rate?

to increase pressure in the glomerulus to increase filtration

what is the juxtaglomerular?

the area next to the glomerulus where the ascending limb of nephron loop and distal convoluted tubules come right next to the glomerulus

what is the composition of urine?

• 95% water

• urea

• uric acid

• trace amounts of amino acids and electrolytes

what is glomerular filtration rate?

in the glomerulus, up to 180L of fluids leave the blood vessels and enter the renal tubule, it is the filtration of the plasma by the glomerular capillaries.

what is fenestrae?

tiny openings that make the capillaries very permeable

what are podocytes

they cover the capillaries so that protein do not escape the blood

factors that control glomerular filtration rate

• GFR increases when body fluids are in excess

• GFR decreases when the body must conserve fluids

• if blood pressure drops, GFR decreases so that less urine forms because the body must conserve water

• if blood pressure rises, GFR increases so that more urine forms because the body needs to get rid of excess water

how does renin affect glomerular filtration rate?

• GFR is lowered with an enzyme called renin

• renin is secreted by the kidney if there is a drop blood pressure, or if there is decreased amounts of Na, Cl, or K

how does aldosterone affect urine formation?

(from the adrenal glands) stimulates reabsorption of sodium

how does ADH affect urine formation?

(from posterior pituitary gland) stimulates reabsorption of water

what role does hypothalamus play in the formation of urine?

• produces ADH which is released the posterior pituitary

• ADH stimulates reabsorption of water so that urine volume drops: keeps the fluid levels and blood pressure from dropping too low

• the amount of urine is a result of the balance between body fluid level and ADH: if fluids are high, ADH is decreased and less water is reabsorbed which produces more urine

• If fluids are low, ADH increased and more water is reabsorbed which produces less urine

ureter, 3 layers

• tube that connects to the bladder

• mucous is the inner coat

• muscular is the middle coat

• fibrous is the outer coat

location of the bladder

pelvic girdle

what is the trigone of the bladder?

triangular area on the floor of the bladder, one opening at each part of the triangle

4 layers of the bladder

• mucous is inner layer

• submucous is 2nd layer

• muscular coat: next layer which makes up the detrusor muscle

• serous is the outer layer

urethra

tube that connects bladder to outside of the body, contains urethral glands which secret mucous into the urethra

what is micturition?

urination

glomerular filtration

GFR is fluid coming out of the blood vessels and into the Renal tubule, a lot of fluid is lost and must be reabsorbed, takes place in the glomerular capsule (blood vessels ➡ renal tubule)

tubular reabsorption

• substances move from the Renal tubule back into the blood vessels (renal tubule ➡ blood vessels).

• the kidney selectively reclaims what it wants to keep, and how much of it is kept: water, electrolytes, glucose

• the waste products are not reclaimed and left in the renal tubule