Organs
What are ureters?
one duct per kidney that transport urine to the bladder
What are nephrons?
What is there function?
BONUS: what does each nephron have?
- microscopic tubule system that helps kidneys blood plasma filtration (all plasma except large proteins)
- secretion, reabsorption, and osmo concentration = urine formation
BONUS: each has Bowman Capsule
What are Juxtaglomerular cells (JG cells)?
what there function?
- controls arteriole radius through smooth muscle cells
- help control MAP fluctuations by vasoconstriction/dilation
What is RAAS and what is it triggered by?
BONUS: what senses the changes causing trigger?
Renin-Angiotensin -Aldosterone System
- triggered by- low blood pressure (baroreceptors or JG cells) and low sodium/filtration volume (macula densa)
What is Glomerular Filtration Rate (GFR)?
what is influenced by?
rate of kidney filtration and health
- volume of blood plasma filtered from all glomerular capillaries per unit of time
- influenced by- change of afferent arteriole radius
Bonus: what sphincters are there and which are voluntary
duct that transports urine from bladder to external environment
- internal (involuntary) and external (voluntary) sphincters
What is the glomerulus?
What is its function?
BONUS: selective or not selective?
- bundle of special capillaries
- controls filtration (RBC, WBC, and platelets)
BONUS: NOT selective
What is the purpose of the sodium and potassium ATPase pump? where is it located?
BONUS: how is it regulated?
drives reabsorption at the apical membrane
in nephron tubules cell basolateral membrane
- transports sodium, glucose, amino acids, water, chloride via channels and carriers
BONUS: hormone regulated
What do the lungs do to participate in this process?
- JG cells secrete Renin into blood which converts angiotensinogen to angiotensin 1
- angiotensin 1 converted to angiotensin 2 through pulmonary circulation to lungs via ACE enzyme
What is different for water dwelling mammals?
BONUS: provide example
weak osmo concentrators as they have cortical nephrons (short loops of Henley) causing lower ability to reabsorb water
BONUS: Beaver!
What does the bladder do? and what is it lined with?
Holds urine
- transitional epithelium that covers smooth muscle
What are tubules functions?
Selective or not selective?
BONUS: what are some channels/carriers used?
- Reabsorption of sodium, glucose, amino acids, ions, and water via assisted membrane transport (channels and carriers)
- Highly selective
BONUS: SGLT, GLUT, Aquaporen channels
What is the sympathetic nervous system do to regulate?
BONUS: what does it help avoid?
contracts JG cells causing afferent arteriole vasocontriction causing decrease in GFR reducing solute and water loss
BONUS: avoids excessive filtration and maintains blood pressure and volume
Where does angiotensin 2 travel to and trigger?
What does this triggered thing do to the tubule system?
BONUS: what else does angiotensin 2 stimulate?
Angiotensin 2 travels to adrenal cortex via blood = aldosterone secretion into blood which travels to the kidneys
-causing increase of sodium reabsorption from tubule system
BONUS: stimulates thirst and salt hunger
What is different in desert dwelling mammals?
BONUS: provide example
strong osmo concentrators with juxtamedullary nephrons (long loops of Henley) causing higher ability to reabsorb water
BONUS: Kangaroo Rat!
What do the kidneys do?
Bonus: what is the shape of the kidney dependent on?
does all the work!
- urine formation, blood plasma filtration, waste/toxin removal, water reabsorption
BONUS: shape based on species!
What is the loop of Henley?
BONUS: what is the countercurrent multiplier system?
- nephrons help create hypertonic environment in kidney medulla for increased water reabsorption potential along distal tubule
BONUS: filtration enters loop to descending limb (water permeable)--> hairpin/thin ascending limb (low water permeability + sodium permeable via leak channels) --> thick ascending limb active transports sodium and chloride out of lumen (impermeable to water)
What does autoregulation do?
What are teh two ways?
BONUS: extrinsic or intrinsic?
prevent unintentional shifts in GFR due to MAP fluctuations
- Myogenic activity- more JG cell stretch from increased BP causing vasoconstriction and decrease of blood into glomerulus
- Tubuloglomerular feedback (TGF)- distal tubule senses sodium concentration change causing release of paracrine factors effecting the JG cell contraction and afferent arteriole vasoconstriction
BONUS: intrinsic
What does water follow? what does it contribute too?
water follows sodium via osmosis in tubule system
- contributes to blood plasma= increase MAP and blood volume
What happens when an animal is hydrated?
large water volume in tubular filtrate exits the loop and enters the distal tubule and collecting duct to the kidney medulla
- increasing water absorption potential into the tissues and blood vessels via osmosis
What are the four sections of the kidney and what are there functions?
- Hilus- blood and lymphatic vessels, neurons, and ureters enter and leave through this
- Renal pelvis- urine collection (near hilus/very middle)
- Renal medulla- osmo concentration (inner layer, pyramid shaped)
- Renal cortex- plasma filteration (outer layer)
What is the Juxtaglomerular apparatus (JGA)?
What functions?
BONUS: what are macula densa?
where the distal tubule (after loop) meets glomerulus
- paracine communication between macula densa and juxtaglomerular cells
BONUS: distal tubule epithelial cells
Where is water reabsorbed? and how?
Where is glucose absorbed? what does high glucose concentration in urine mean?
- water reabsorbed alone proximal tubule by osmosis (aquaporin channels)
- proximal tubules absorb glucose until threshold is met
- high glucose concentration = diabetes mellitus indication
What is Atrial natriuretic peptides (ANRs)?
What does it inhibit/reduce?
hormones released by heart atria myocardiocytes in response to high blood pressure/volume
- reduces sympathetic output and inhibits RAAS
What happens when an animal is dehydrated?
vasopressin is released from posterior pituitary, increasing aquaproin channel numbers, since water is attracted to high solute concentration, it attracts to the outside of the duct and gets reabsorbed out of tubule into blood vessels
- low urine volume and very concentrated (hypertonic)