Phys 3 Final (copy)

What does the renal artery divide into?

1. segmental arteries

2. Interlobar arteries→ up renal columns, between pyramids

3. arcuate arteries→ over pyramids

4. Cortical radiate arteries→ up into cortex

5. Afferent arterioles→ supplying one nephron

leads to a ball of capillaries→ glomerulus→ filtering feature of nephron

T/F Veins have same course as arteries but in reverse

true→ NO SEGMENTAL VEINS

Blood is drained from the glomerulus by __

efferent arterioles

Where do efferent arterioles lead to?

peritubular capillaries

T/F some efferent arterioles lead to the vasa recta

true

Where does peritubular capillaries lead to?

cortical radiate vein or directly into arcuate vein→ interlobar vein→ renal vein

Where does the renal vein empty into?

inferior vena cava

What does the pertibular capillaries surround?

In cortex, they surround PCT and DCT

What does the vasa recta surround?

In the medulla, surrounds the nephron loop

What is the majority of nephrons?

cortical nephrons

What are some features of cortical nephrons?

• short nephron loops→ involved in reabsorption

• efferent arterioles branch into peritubular capillaries around PCT and DCT

What makes up 15% of nephrons? What are some key features?

Juxtamedullary nephrons 

• very long nephron loops→ maintain salty gradient in medulla and help conserve water

• efferent arterioles branch into vasa recta around long nephron loop

What is each nephron composed of?

1. renal corpuscle→ filtration of blood plasma

2. Renal tubules→ long, coiled tube that converts the filtrate into urine

__ consists of the glomerulus and a two layered glomerular capsule that encloses glomerulus

Renal corpuscle

What are the two layers of bowman’s capsule?

1. Parietal layer (outer)

2. Visceral layer (inner)→ consists of podocytes that wrap around the capillaries of glomerulus

What are the four regions of the renal tubule?

1. Proximal convoluted tubule

2. nephron loop

3. distal convoluted tubule

4. collecting duct

PCT arises from ___ _

glomerular capsule

What are some features of the PCT?

1. longest and coiled region

2. covered by microvilli producing a brush border for reabsorption

3. transports ions cross their membrane (uses lots of ATP)

T/F Kidneys are only 0.4% of body weight, but receive about 21-25% of cardiac output

true

What is the nephron loop long U-shaped portion of renal tubule called?

Loop of Henle

What are the two parts of the Loop of Henle?

1. Descending (Thin)→ permeable to water

2. Ascending (Thick)→ impermeable to water and engaged in active transport of salts

What begins shortly after the ascending limb reenters the cortex?

Distal convoluted tubule (DCT)

What are some features of DCT?

1. shorter and less coiled than PCT

2. no brush border

3. pumps ions aganist their concentration gradient so they still have many mitochondria

4. MARKS END OF NEPHRON

What receives fluid from the DCTs of several nephrons as it passes back into medulla?

Collecting duct

What are some key features of collecting duct?

1. facilitates water reabsorption

2. numerous collecting ducts converge toward the tip of the medullary pyramid

3. Papillary/terminal duct→ formed by merger of several collecting ducts

Kidneys convert blood plasma to urine in what four stages?

1. Glomerular filtration

2. Tubular reabsorption

3. Tubular secretion

4. Water conservation

What is glomerular filtrate?

fluid in the capsular space

What is tubular fluid?

fluid from the PCT through DCT

What is urine?

fluid that enters collecting duct

What are three parts of the glomerular filtration membrane?

1. Fenestrated endothelium of glomerular capillaries

2. Basement membrane

3. Filtration slits

What is the fenestrated endothelium of glomerular capillaries?

70-90nm filtration pores→ small enough to exclude blood

highly permeable

What is basement membrane?

proteoglycan gel with a negative charge

albumin repelled by negative charge

What is filtration slits?

made by podocyte extensions that wrap around the capillaries to form barrier layer with filtration slits

T/F kidney infections and trauma can damage the filtration membrane and allow albumin or blood cells to filter

true→ proteinuria (presence of protein in urine) and hematuria (presence of blood in the urine)

T/F distance runners and swimmers often experience temporary proteinuria or hematuria

true

What is filtration fraction?

fraction of blood plasma in the afferent arterioles that become filtrate

What is pushing out in bowman’s capsule?

blood hydrostatic pressure (55mm Hg)

What three factors determine net filtration pressure?

1. Hydrostatic pressure (promotes filtration)

2. Capsular hydrostatic pressure (opposes filtration)

3. Colloid osmotic force (opposes filtration)

What is the average capsular pressure?

15 mm Hg

What is the pressure that is the result of proteins present in blood plasma?

blood colloid osmotic pressure

What is the average pressure of blood colloid osmotic pressure?

30 mm Hg

Wha is the net filtration pressure?

10 mm Hg

What happens if NFP increases?

glomerulus makes kidneys vulnerable to hypertension

What is the amount of filtrate formed per minute by the two kidneys combined?

Glomerular filtration rate

What is the average GFR?

125 mL/min

How to calculate GFR?

NFP x Kf (for every 1mmHG of NFP→12.5mL of filtrate is made)

What occurs if GFR is too high?

1. fluid flows through renal tubules too rapidly

2. decreases reabsorption

3. urine output rises

4. chance of dehydration

What occurs if GFR is too low?

1. wastes are reabsorbed→ waste accumulate

2. Azotemia (high nitrogenous waste in body) may occur

Within PCT, __ reabsorption is key

Sodium→ (most abundant cation in filtrate)

What are the two routes for sodium reabsorption?

1. Transcellular route→ aquaporin

2. Paracellular route→ creates solvent drag

What channels does the descending loop have?

aquaporin channels

What type of channels does the ascending loop have?

Na, K, and Cl- symporters

What are the three ways GFR is controlled?

1. Renal autoregulation→ myogenic mechanism and tubuloglomerular feedback

2. Sympathetic controle

3. Hormonal control

What is myogenic mehcanism?

tendency of most smooth muscle ot contract when it is stretched and relax when its not

If arterial blood pressure increases, smooth muscles cells __

will stretch and then vasoconstrict

If arterial blood pressure falls, smooth muscle cells will __

vasodilate

Tubuloglomerular feedback acts as a checkpoint and __

gives feedback to afferent arteriole

What is the juxtaglomerular apparatus?

structure found at end of nephron loop

in contact with afferent/efferent arterioles

What are the three cells found in the juxtaglomerular apparatus?

1. Macula densa→ sensory cells that respond to changes in fluid rate and NA+ concentration

2. Granular cells → modified smooth muscle cells

3. Mesangial cells (intra/extraglomerular cells)

What will happen to GFR under sympathetic control?

GFR will slow down

When do we make Angiotensin II?

low blood pressure

low GFR→ need to speed it up via mesangial cells

What is the main function of DCT?

hormonal control

What are the two types of cells in the DCT?

1. Principle cells

2. Interclated cells

PCT reabsorbs about __ of glomerular filtrate

65%

What are the three factors that promote osmosis in the capillaries?

1. High interstitial fluid pressure

2. low blood hydrostatic pressure in peritubular capillaries

3. high colloid osmotic pressure

The nephron loop creates __

counter current multiplier (saltiness of water)

The vasa recta is the __

counter current exchanger and helps maintain medullary concentration

What are some features of principal cells?

Most numerous

involved in salt and water balance

What is the function of intercalated cells?

involved in acid-base balance by secreting H+ into tubule lumen and reabsorbing K+

What is the function of aldostrone?

salt retaining hormone

triggered when:

• when blood sodium is low

• when potassium rises

• drops in blood pressure→ RAAS→ aldostrone

What is the function of ADH and when is it triggered?

water reabsorption 

released when:

• dehydration, loss of blood volume

What is the function of ANP?

lower blood pressure and volume

excrete more salt and water in the urine

How does ANP lower blood pressure and volume?

1. inhibits renin and aldosterone

2. inhibits secretion of ADH

3. inhibits NaCl reabsorption in collecting duct

What is the function of Parathyroid hormone? How does it achieve its goal?

increase calcium levels

acts of PCT to inhibit phosphate reabsorption and acts on DCT to increase calcium reabsorption

What is water diuresis?

drinking large volumes of water or hypotonic fluid will produce large volumes of hypotonic urine

When does diuresis begin?

15 minutes after ingestion

What does a dipstick test check for?

1. Blood

2. billirubin

3. nitrites

4. leukocytes

5. protein

6. ketones

7. glucose

Where is the only place that glucose is absorbed?

PCT

With both diabetes mellitus type 1 and 2, what will their urine look like?

glycosuria (glucose in urine)

polyuria

With Central diabetes insipidus, what does the urine look like?

hyposecretion of ADH (aldosterone can take over)

more water passes in urine (polyuria)

Why do people with nephrogenic diabetes insipidus have polyuria?

principle cells have decreased sensitivity to ADH

ADH increases but no water reabsorption

What effect does caffeine have on GFR?

caffeine dilates afferent arteriole→ increased GFR

What effect does alcohol have on ADH?

inhibits ADH secretion

What are loop diuretics?

inhibits Na+, K+. amd Cl- symport→ impairs countercurrent multiplier→ reducing osmotic gradient→ collecting duct unable to reabsorb as much water

What moves the urine from kidney into the bladder without aid from gravity?

ureters

What transports urine from bladder to outside the body?

urethra

What occurs during the storage phase?

periaqueductal gray will inhibit pontine micturation center

What occurs during the voiding phase?

periaqueductal gray no longer inhibits pontine micturation center

What is the sympathetic response during the storage phase?

hypogastric nerve activated→ detrusor muscle rx, IUS cx

What is the parasympathetic response to the storage phase?

pelvic nerve inhibited→ detrusor muscle rx

What is the somatic response to the storage phase?

pudendal nerve activated→ EUS cx

What is the sympathetic response during the voiding phase?

hypogastric nerve inhibited→ detrusor cx, IUS rx

What is the parasympathetic response to the voiding phase?

pelvic nerve activated→ detrusor nerve cx

What is the somatic response to the voiding phase?

pudendal nerve inhibited→ EUS rx

__% is intracellular fluid

65

__% extracellular fluid

35

• 25% tissues

• 8% blood plasma

• 2% transcellular fluid

T/F Through osmosis, water will move from high to low concentration

true

Molecules moving against its concentration gradient (consuming energy) is called __

Active transport

Molecules pass through the membrane is called __

passive transport

Molecules moving down a concentration gradient through special protein channels is called __

facilitated transport