Biol 204 exam 3 lecture 1

kidneys

filter the blood to remove metabolic wastes, toxins etc

This process produces urine

Uterer

Tubes that connect kidneys to bladder

urinary bladder

connected to the kidneys via the uterer, stores the urine

urethera

connected to urinary bladder, urine is expelled from the body to the tube

what type of organs are the kidney, uterer, bladder, and urethera?

organs of excretion, which remove wastes and water from the body

Where are the kidneys situated?

Against the posterior abdominal wall

What does the kidney excrete

urea, creatine, and uric acid

c urea c uri (nitrogenous waste)

and ingested toxins

Nitrogenous waste

urea, creatine, and uric acid

c urea c uri (Korea Curry)

excreted by kidney

what does the kidney Regulate

Water and electrolytes

Acid base

arterial BP

WAR (waghhh)

What does the kidney produce in its syntheic function

erythopoietin

1-25 dihydroxy vitamin D3 (calcitriol)

renin

4-evr

Functions of the kidneys

Regulation, excretion, synthetic function

Where are nephrons

within the renal pyramids in the medulla and in the cortex depending on type

renal cortex

houses blood vessels and most parts of the nephrons

renal medulla

inner portion of kidney that exhibits cone shaped pyramids seperated by columns

renal pyramid

bundles of collecting tubules

Renal column

seperates renal medullas

Renal pelvis

flat, funnel shaped tube that forms drainage and collection areas for urine

What are nephrons

the structural and functional units of the kidneys (filtering units)

can be juxtamedullary or cortical

How much nephrons are there

1 million per kidney

Cortical nephrons location

located almost entirely in the renal cortex

Juxtamedullary nephrons location

15% located closer to the renal medulla

Nephron anatomy

Renal corpuscle (filters the blood)

renal tubule (converts the filtrate to urine)

renal corpuscle purpose

part of nephron that filters the blood

renal tubule purpose

part of nephron that converts filtrate from the renal corpuscle into urine

Bowman’s capsule

cup shaped hollow structure that surrounds the glommerulus

outer part of the renal corpuscle

Glommerulus

part of renal corpuscle surrounded by bowmans capsule

knot of capillaries wrapped by podocytes

Layers of bowman’s capsule

parietal layer

capsular space with ultrafiltrate

visceral layer

visceral layer of bowmans capsule

the podocytes that wrap around the glomerulus capillaries

Flow of blood filtration in bowman’s capsule

what is the parietal layer of bown’s capsule made of

simple squamous epithelium

Glomerrular filtration

process of which water and some solutes in the blood plasma pass from the capillaries of the glomerulus into the capsular space of the nephron

Afferent atriole

Brings blood to the glommerulus capillaries in the renal corpuscle

efferent atriole

carries away blood from the glommerulus capillaries in the renal corpuscle

Glommerular filtration process

1. afferent atriole brings in blood to the glommerulus in the renal capsule

2. Filtered blood enters the capsular space, which then enters the renal lumen of the nephron

3. The efferent atriole takes the blood away from the glomeerulus

Passive process that requires a pressure gradient to work

false, glomerulus blood flow gees

Net filtration pressure

total pressure that promotes filtration

NFP = favors that favor filtration (GHP) - forces that oppose it (GCOP + CHP)

GHP

Glomerullar hydrostatic pressure

pressure in glomerulus wanting to come out

favors filtration

GCOP

glommerular collloid osmotic pressure

due to proteins like albumins bringing in water

unfavorable to filtration

CHP

capsular hysrostatic pressure

due to capsular space of bowman’s capsule accumulating with liquid and opposing flow

unfavorable to filtration

In order for filtration to happen, what do the pressures in the renal corpuscle need to be?

Glomerulus needs to be higher

Bowmans capsule capuslar space needs to be lower

true, venules have lower pressure

Why is it that the glommerulus uses two atrioles betwen as opposed to the ususal flow of one atriole to capilaries to venule?

Arterioles can constrict and dialate

For example, if you constrict the efferent atriole (moves blood away)

Pressure in the glomerulus goes up, and filtration goes up

For example, if you dialate the efferent atriole (moves blood away)

Pressure in the glomerulus goes down, and filtration goes down

The venules just hold the blood, lots of pressure, lots of room

Basement membrane of the glomerulus

middle layer

consists of proteoglycan gel, prevents filtration of large proteins

Fenestrated endothelium of the capillary

prevents filtration of blood cells, innrmost layer of glommerulus

Filtration slits between pedicels

outermost barrier to filtration which is a negativley charged obstacle for large Anions, and prevents filtration of medium sized proteins

Barriers to filtration in glommerulus

1. fenestrated endothelium in the capillary

2. basement membrane

3. filtration slits between pedicels

1. prevents blood cells 2. prevents large proteins 3. prevents anions and proteins due to negative charge

Pedicels

foot processes of podocytes that wrap around capillaries and interdigitate with each other

Filtration slit

narrow gap between two pediciels that is covered by a thin structure called the slit diaphragm, made of proteins

What can pass the filtration membrane in the glommerulus?

less than 3 nm, smaller than protiens

Glommerular filtration rate

ampunt of filtrate created by renal corpuscle per minute

Male glommerullar filtration rate

125 mL/min (180 L/day)

Female glommerullar filtration rate

105 mL/min (150 L/day)

What is a Glomerullar filtration rate of less than 60 indicative of

kindey disease or failure

Too low Glomerullar filtration rate

Fluid flows sluggishly through the renal tubules, and they reabsorb wastes that should be eliminated in the urine

too high Glomerullar filtration rate

Fluid flow fast through the renal tubules, and they cant reabsorb water and solutes

Leads to dehydration and electrolyte depletion

Intrinsic controls of GFR meaning

local regulatory mechanisms within the kidney (autoregulation)

Intrinsic controls of GFR primary goals

maintains stable GFR despite noromal fluctuations in BP (normal homeostasis)

when are the Intrinsic controls of GFR activated

During normal blood pressure fluctuations, around 80-1280 mmHg MAP

mechanisms of Intrinsic controls of GFR

Myogenic mechanism

tubuloglomerular feedback

speed of Intrinsic controls of GFR

rapid

intrinsic conrols of GFR effect on GFR

stabilizes it

Extrinsic controls of GFR definition

systemic regulatory mechanisms outside the kidney

Extrinsic controls of GFR goal

prioritizes blood volume volume during stress or severe changes over GFR

when are the Extrinsic controls of GFR activated

during significant hypotension, blood loss, dehydration, or stress

what are the main mechanisms of Extrinsic controls of GFR

1. SNS

2. renin-agiotensin-aldoseterone system

3. hormonal influences

speed of Extrinsic controls of GFR

slightly slower than intrinsic controls of GFR (minutes to hours)

effect of Extrinsic controls of GFR

Decreases GFR to conserve fluid (expect for efferent atriole constriction)

High blood pressure arteriole myogenic mechanism

Intrinsic control of GFR

1. High blood pressure leads to increased hydrostatic pressure inside the afferent atriole leads to a stretch

2. stretch leads to an influx in ca2+

3. ca2+ leads to contraction

4. diameter then decreases in afferent atriole

5. this leads to vasoconstriction

6. Leads to lower glomerular pressure

7. less net flow from glomerulus to capsule space of bowman’s capsule

8. lower GFR

low blood pressure arteriole myogenic mechanism

1. low blood pressure leads to decreased hydrostatic pressure inside the afferent atriole

2. smooth muscle relaxes

3. leads to decreased vasodilation in the afferent atriole

4. leads to higher flow

5. Leads to higher glomerular pressure

6. more net flow from glomerulus to capsule space of bowman’s capsule

7. higherGFR

Location of juxtaglomerular apparatus

Macula densa

Intrinsic control of GFR, part of juxtaglomerular apparatus

collection of densely packed epithelial cells in distal convoluted tube that sense nacl by absorbing it via NKCC2 transporter

juxtaglomerrular cells

Intrinsic control of GFR, part of juxtaglomerular apparatus

in afferent atriole

derived form smooth muscle cells of efferent atriole, secrete renin (enzyme)

extraglomerular mesangial cells

act as a mechanical anchor between afferent atriole, efferent atriole and macula densa

Tuberomerular feedback - high nacl

1. High GFR leads to high tubular flow

2. high amounts of Nacl delivered to the macula densa

3. increased NaCl uptake triggers ATP release

4. ATP is rapidly converted into adenosine which causes the efferent atriole to vasoconstrict

5. GFR decreases

6. Adenosine acts on JG cells, which inhibit renin release

Tuberomerular feedback - LOW

NaCl

1. low GFR leads to low tubular flow

2. low amounts of Nacl delivered to the macula densa

3. decreased NaCl uptake triggers less ATP release, which is then turned into adenosine

4. less adenosine release leads to prostoglandin release

5. prostoglandin acts on JG cells, which activates RAAS

6. RAAS helps restore GFR

Granular cells

part of afferent atriole in juxtaglomerrular apparatus

Renin aldosterone system

1. The liver constantly produces angiotensinogen, an innactive precursor circulating in blood

2. Blood pressure falls, Juxtoglomerular cells release renin

3. in the bloodstream, renin converts angiotensinogen into angiotensinogen I

4. in the lungs and vascular endothelium ACE (angiotensin convertin enzyme) converts angiotensin I into angiotensin II (active form of angiotensin I)

5. angiotensin II makes adrenal gland release aldosterone , which stimulates the reabsorbtion of sodium and water

6. angiotensin II also acts on the smooth muscle to constrict blood vessels (the kidney prefers the efferent atriole)

What does angiotensin II do?

active form of angiotensin I

1. angiotensin II makes adrenal gland release aldosterone , which stimulates the reabsorbtion of sodium and water

2. angiotensin II also acts on the smooth muscle to constrict blood vessels

What does RAAS result in?

Increased blood volume

increased blood pressure

restoration of GFR

Flow of glomerular filtrate

What does the collecting duct do?

recieves fluid form DCTs of several nephrons

Flow of fluid from papillary duct to the urinary bladder