Chapter 26 the urinary system Flashcards
What does the urinary system consist of?
- Two Kidneys
- Two ureters
- One bladder
- One urethra
What does the urinary system do?
Maintain homeostasis by managing the volume and composition of fluid reservoirs, primarily blood
What’s part of blood ionic composition?
- Na
- K
- Cl
What is involved in the regulation of pH?
- H
- HCO
What is involved with the regulation of blood volume?
H2O
What are the functions of a homeostatic kidney?
- Maintenance of blood osmolarity
- Production of hormones
- Excretion of metabolic wastes and foreign substances
- Regulation of blood glucose levels
What are the external layers of the kidney? (superficial to deep)
- renal fascia
- adipose capsule
- Renal capsule
What is the renal cortex?
Outer layer of the kidney
What is the renal medulla?
Inner region
Although kidneys constitute less then 0.5% of total body mass they receive how much cardiac output?
20-25%
Renal nerves primary carry what kind of flow?
sympathetic outflow
What does the nerve supply do inside the kidney?
Regulate blood flow through the kidneys
What are the different types of blood vessels in the kidney?
- Renal artery and renal vein
- Afferent arteriole- glomerulus capsule- efferent arteriole
- peritubular capillaries
What is the glomerulus?
A mass of capillaries that is fed by the afferent arteriole and drains into the efferent arteriole and is surrounded by the Bowman’s capsule
What is the bowman’s capsule?
Double walled structure which wraps around the capillaries and
1. filtrate is collected between the visceral and parietal layers
2. Contains fluid rich in solutes, free of proteins
What are the two parts of the renal corpuscle?
- Glomerulus
- Bowman’s capsule
What is the renal tubule?
Site of reabsorption and secretion
What are the three sections of the renal tubule?
- proximal convoluted tubule
- Loop of henle/ nephron loop
- Distal convoluted tubule
What are the sections of the loop of henle/ nephron loop?
Two parts
1. Cortical nephron
2. Justamedullary nephron
What is the cortical nephron?
- renal corpuscle in outer portion of cortex
- Short loops of Henle extend only into outer region of medulla
- Receives blood from peritubular capillaries arising from the glomerulus arterioles
The cortical nephrons make up how much of the nephrons?
80-85%
What is the juxtamedullary nephron?
- Renal corpuscle deep in cortex with long nephron loops
- Receive blood from peritubular capillaries and vasa recta arising form the efferent glomerulus arterioles
- Ascending limb has thick and thin regions
What is the basic process involved in urine formation?
Glomerular filtration + secretion - reabsorption
What are the steps for urine formation?
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
What is glomerular filtration?
- Driven by blood pressure
- Water and small molecules such as sodium and potassium, move out of the glomerulus
- Glomerular hydrostatic pressure
What is glomerular hydrostatic pressure?
Opposed by capsular hydrostatic pressure and blood colloid osmotic pressure
What is glomerular filtration rate?
Amount of filtrate formed by both kidneys each minute
Homeostasis requires kidneys to maintain what?
A relatively constant Glomerular filtration rate
What happens if the GFR is too high?
Substances pass to quickly and are not reabsorbed
What happens if GFR is too low?
Nearly all reabsorbed and some waste products not adequately excreted
What happens in tubular reabsorption and secretion?
much of the filtrate is reabsorbed, especially
1. water
2. glucose
3. Amino acids
4. Ions into the blood
What must we keep in mind in terms of tubular reabsorption and secretion?
- location
- Ratios of reabsorption
What does secretions assist with?
- managing pH levels
- Riding the body of toxic and foreign substances
What are enzymes, hormones of the kidney’s
- Antidiuretic hormone
- Aldosterone
- Atrial natriuretic factor
- Renin
- Erythropoietin
What does Antidiuretic hormone do?
Increase facultative reabsorption of water, which decreases osmolarity of blood fluid
What does Atrial Natriuretic peptide (ANP) do?
- Increases excretion of Na in urine
- Increases urine output and thus decreases blood volume and blood pressure
What does Angiotensin do?
Increases reabsorption of Na and water, which increases blood volume and pressure
What does Aldosterone do?
Increases secretion of K and reabsorption of Na; increases reabsorption of water, which increases blood volume and blood pressure
What must we keep in mind in terms of urine production?
- Fluid intake is highly variable
- Homeostasis requires maintenance of fluid volumes within specific limits
- Urine concentration varies with ADH
What does high intake of fluid results in?
dilute urine of high volume
What does low intake of fluids results in?
concentrated urine of low volume
Routine urinalysis does what?
evaluates the presence of abnormalities in urine
What are some things to look for in urine?
- Albumin
- Glucose
- Red Blood cells
- Ketone bodies
- Microbes
Each ureter transports urine from a renal pelvis by what?
- Peristaltic waves
- Hydrostatic pressure
- gravity
Is there a valve at the opening of the bladder?
no
What happens when the bladder fills?
it compresses the opening and prevents backflow
How much fluid can the average bladder carry?
700-800 ml
What does the kidney do?
- Regulate blood volume and composition
- Help regulate blood pressure
- Synthesize glucose
- Release erythropoietin
- participate in Vitamin D synthesis
- excrete wastes in urine
What does the ureters do?
Transports tubes that move urine from kidneys to urinary bladder
What is the urinary bladder?
Storage organ that temporarily stores urine until convenient to discharge from body
What is the urethra?
Drainage tube that transports stored urine from body
What is micturition?
Discharge of urine
What is the trigger for micturition?
- stretch receptors trigger a spinal reflex
- urethra carries urine from internal urethra to exterior of body
- Males have a mix of semen in urine as well
