Urinary Flashcards
Roles of Urinary system
- Cleansing the blood
- regulation of pH
- Regulation of Blood pressure (nephron)
- Regulating the concentration of blood Solutes
- Determins the concentration of RBC (epo production) (nephron)
- Final synthesis of vitamin D (converting calcidiol to calcitriol) (nephron)
Symptoms from Kidney disfunction
Weakness Lethargy shortness of breath anemia widespread edema (swelling) Metabolic acidosis rising K+ levels heart arrhythmias etc...
What other system controls the urinary system
nervous- failure will result in Incontinence
The kidneys receive ____% of RESTING cardiac output
20-25%
they are extremely well vascularized
What part of the Endocrine system is on top of the kidney. What is it’s role?
- The Adrenal Gland
- Adrenal cortex = produces aldosterone to stimulate sodium reabsorption
- Adrenal Medulla = release catecholamines (epinephrine and norepinephrine)
Renal Column Role
- connective tissue
- separate the renal pyramids
- divides kidney into 6-8 lobes
- supportive framework for vessels that entre and exit cortex
Renal Pyramid Role
- bundles of collecting ducts
- transport urine from nephrons to calyces for excretion
What makes the kidney lobes
Pyramids and renal columns
renal hilum role
-entry and exit point
-
Renal Pelvis Placement and role
- Emerges from hilum
- formed from major and minor calyxes in kidney
Renal Arteries and veins
- Renal arteries from descending aorta through hilum to bring blood
- Renal veins return cleansed blood through hilum into inferior vena cava
Nephrons: role, anatomy, and types
- functional units
- balance the plasma to homeostatic set points and excrete potential toxins
- afferent arterioles supply blood through glomerulus capillaries
- Glomerular/ Bowman’s Capsule receives filtrate
- Cortical nephrons: short loop of Henle that barely leaves cortex
- Juxtamedullary nephrons: long loop of Henle that goes into Medulla
Renal Corpuscle
-Bowman’s capsule + Glomerulus = renal corpuscle
Bowman’s Capsule
-Continuous sophisticated tubule with proximal end that surrounds the glomerulus and receives filtrate
Order of flow through a cortical nephron
-Glomerular (Bowman’s) capsule
-Proximal convoluted tubule
-Descending limb of the nephron loop
-Ascending limb of the nephron loop
-Distal convoluted tubule
(drains into collecting duct)
After passing through the renal corpuscle the capillaries form ……
Which then…..
- a second arteriole , efferent arteriole
- forms capillary network around distal portions of nephron tubule (Peritubular capillaries and Vasa recta) -> then returns blood (mostly water and solutes) to venous system
Why is the Renal Cortex easy to distinguish? What is found there?
- It is lighter in colour then the rest of the kidney
- Renal Corpuscles, Proximal convoluted tubules, and distal convoluted tubules
3 steps/ principals of nephron
Filtration
reabsorption
secretion
What factors allow substances to cross into the nephron
- fenestrations : prevent filtration of blood cells or large proteins (but allow most other things)
- Electric Charge: proteins associated with the pores are negatively charged, so they repel negatively charged substances and allow positively charged substances
- Therefore no blood cells or large proteins should be in urine and there is a slight positive charge (Na+, K+)
Loop of Henle, function and Anatomy
Descending: initially thick, then thin
Ascending: initially thin, then thick
Thick part of loop: simple cuboidal epithelium
This part of loop: Simple Squamous epithelium
-allows varying permeabilities for solutes and water
Convoluted tubule. Why named that? Role? Anatomy?
- progressively widening path
- simple cuboidal cells form it with prominent Microvilli on Luminal Surface, forming Brush Border
- this structure is key to reabsorb solutes (Na+, Cl-, glucose, etc.)
Distal convoluted tubule
- simple cuboidal epithelium
- Shorter & Less active then Proximal Convoluted Tubule in absorption and secretion -> fewer microvilli on apical surface and no brush border
Where are the Macula Densa cells. What is their role?
Juxtaglomerular apparatus
- release paracrine signals (w/ ATP) as a response to Na+ in fluid
- Regulate renin release
- -> Renin takes A.As off of angiotensinogen to make angiotensin I
Where are juxtaglomerular cells? What do they do?
in juxtaglomerular apparatus
-is a modified smooth muscle cell lining the afferent arteriole that can contract or relax in response to ATP or Adenosine
-
Steps of the Nephron
1) GFR increases
2) Flow through tubule increases
3) flow past macula densa increases
4) Paracrine from macula densa to afferent arteriolr
5)Afferent arteriole constricts
-Resistance in afferent arteriole
-Hydrostatic Pressure in glomerulus decreases
GFR decreases
What is it called when filtrate osmolarity is too high? How does the system react?
Hyperosmotic
-juxtaglomerular cells contract, decreasing GFR, so less plasma is filtered, leading to less using formation and greater fluid retention
(ultimately will decrease blood osmolarity toward physiological norm.
What happens when osmolarity of filtrate is too low? How does the body react?
juxtaglomerular cells will relax
-increases GFR and increasing loss of water to the urine, causing blood osmolarity to rise to norm
Angiotensinogen-> Angiotensin I-> Angiotensin II
- Made from renin breaking A.As off of Angiotensinogen
- Angiotensin I is not active until converted to Angiotensin II by angiotensin converting enzyme
- Angiotensin II is a vasoconstrictor that increases blood pressure
- Angiotensin II also stimulates aldosterone hormone release
Aldosterone: where released from, and role
-released from Adrenal cortex
-stimulates Na+ reabsorption by kidney
(resulting in water retention and Increased blood pressure)
Natriuretic hormones
- peptides that stimulate kidneys to excrete Na+
- inhibit aldosterone release-> inhibiting Na+ recovery in collecting duct
- also inhibit ADH release-> less water being recovered in the collecting ducts
Collecting Ducts
-Continuous with nephron (but not part of it)
-Collects filtrate from multiple nephrons for modification
-will merge with other collecting ducts and they head towards Medulla
Forming ~30 terminal ducts
-terminal ducts empty at Papilla
-lined with simple squamous epithelium with ADH receptors
-have aqua porin channel proteins in membranes
Aqua Porin Channel proteins in collecting duct allow for:?
water to readily pass from duct lumen through the cells and into the interstitial spaces to be recovered by vasa recta
allows for recovery of lots of water back into blood
-in absence of ADH channels aren’t inserted into membrane, so water can’t be reabsorbed, so it is excreted as dilute urine
How do different urine molecules/ ions move from cell membranes?
- Na+ : active transport
- Anion reabsorption: electrochemical gradient
- Water moves by osmosis (following solute reabsorption)
- other solutes increase as amount of fluid in Lumen decreases
- permeable solutes by diffusion
volume of flitrate formed by both kidneys per minute is called:
Glomerular Filtration rate
How much blood does the heart pump at rest
What is the rate of kidney filtration
how much filtrate a day
How much urine a day
~5L blood per minute
About 1 L will enter kidneys for filtration
therefore ~125mL/min filtrate produced in men and 105mL filtrate/min in women
This becomes about 180L/day in men
150L/day in women
>95% is reabsorbed to circulation
therefore 1-2 L of urine per day
what influences Glomerular filration rate
Hydrostatic pressure and colloid osmotic pressure on either side of the capillary membrane of the glomerulus
Filtration occurs as pressure forces fluid and solutes through a semipermeable barrier with the solute movement constrained by particle size
Hypdrostatic pressure
Influences glomerular filtration rate
is the pressure produced by a fluid against a surface
If you have a fluid on both sides of a barrier, both fluids exert a pressure in opposing directions
->Net fluid movement will be in the direction of the lower pressure
Osmosis
Osmosis is the movement of water across a membrane (that is impermeable to a solute in the solution)
•This creates osmotic pressure, which will exist until the solute concentration is the same on both sides of a semipermeable membrane
•As long as solute concentration differs across the membrane, water will be pulled to the higher solute concentration
Glomerular hydrostatic pressure EXCEEDING capsular (luminal) hydrostatic pressure will cause? How is this related to osmotic pressure?
Glomerular filtration-> also needs to take into account osmotic pressure
•Typically much higher in the glomerular capillary (blood colloid osmotic pressure)
