Module 18: The Urinary System Flashcards
Functions of the urinary system
removes waste from blood excretes in form of urine controls acid-base balance regulates fluid balance regulates electrolyte balance stimulates the production of RBC controls blood pressure
Organs of urinary system
2 kidneys
2ureters
urinary bladder
urethra
Kidney
Highly vascular
Retroperitoneal organ
3 parts of kidney
renal cortex (outer) Renal medulla (middle) Renal pelvis (inner)
surrounding each kidney are 3 layers of tissue
fibrous capsule (inner) peritoneal fat capsule (middle) Renal fascia (outer)
Hilum
notch where ureter leaves the kidney and blood vessels, nerves, lymph vessels enter and leave the kidney
Renal pyramids
triangular structures that look striated due to renal tubules
Renal papillae
tips of pyramids
Minor calyces
surround the tip of each renal pyramid
funnel shaped structures
Function is to collect urine from the ducts of pyramids
Major calyces
join together to form large collecting area called renal pelvis
Nephrons
microscopic units of kidney that regulate the composition and volume of blood and form urine
Nephron consists of glomerulus, bowman capsule, renal tubule
Glomerulus
network of capillaries
surrounded by bowman capsule
where blood is filtered
Bowmans capsule
receive filtered blood (filtrate) from glomerulus and deliver to renal tubule
contains fluid that is the raw material of urine
Renal tubule
long convoluted tube
site of urine formation by reabsorption and secretion
juxtaglomerular apparatus is what regulates the rate of filtrate formation
3 parts of renal tubule
Proximal convoluted tubule
loop of hence
distal convoluted tubule (then leads to collecting duct)
3 steps of urine formation
glomerular filtration
tubular reabsorption
tubular secretion
Physical properties of urine
clear fluid
light yellow
slight odor
chemical properties of urine
95% water
5% urea, na, cl, k ,ca, mg, sulfates, phos, bicarbonates, uric acid, ammonium ions, creatinine
slightly acidic Ph 4.5-8
Antidiuretic hormone (ADH)
synthesized in the hypothalamus
stores and secreted by posterior pituitary gland
High levels of ADH increase water reabsorption
Low levels of ADH decrease water reabsorption
Aldosterone
hormone released by adrenal glands
helps regulate fluid balance
stimulates distal tubules to reabsorb Na+ and water, and to excrete K+
Atrial Natriuretic Peptide (ABP)
inhibits the reabsorption of Na+ and water
decreasing blood volume and pressure
Renin
secreted by juxtaglomerular apparatus
involved with control of blood
leads to formation of angiotensin I which converts to angiotensin II
angiotensin II raises blood pressure
Erythropoietin (EPO)
secreted by kidneys in response to low oxygen in arterial blood
targets bone marrow
stimulates production of RBC
Ureters
long tubes
wave like contraction of smooth muscle in walls of ureters move urine down towards the baldder
Bladder
resembles inflatable balloon 3 openings (2ureter, 1 urethra) form Trigone
3 layers of smooth muscle collectively called detrusor muscle
Transitional epithelium mucous membrane
Urethra
female 3-4cm
male 20cm
3 regions: prostatic, membranous, spongy(penile)
micturition
aka voiding or urination
detrusor muscle contracts
control of micturition
when bladder is partially full, stretch receptors transmit nerve impulses to spinal cord; initiate conscious desire to expel urine and micturition reflex (unconscious)
Exit of bladder is internal sphincter (involuntary contraction)
External sphincter is voluntary
