Renal Anatomy Flashcards
1
Q
What is the blood supply to the kidneys?
A
- comes from the abdominal aorta through renal arteries
- drain through renal vein (25% of blood you have right now is going to kidneys so this vein is large)
2
Q
A
-all of these structures are retroperitoneal
3
Q
A
- gonadal arteries are long because gonads develop high up
- kidneys and gonads pass each other during development when gonads descend and gonads ascend
- right kidney should be lower than left
- bladder sits behind pubic symphysis and starts to come over the top when it fills up
4
Q
A
- liver moves a lot when you breathe
- kidney moves in too
- perirenal fat provides some cushioning
- only half of kidney is protected by ribs (if you get blunt force to the back, these could pierce kidney)
5
Q
A
6
Q
What is the renal hilum?
A
- hilum is area where things enter and exit organ
- area where fat goes into kidney
- where blood supply comes in (arteries in, veins out) and ureter goes out
7
Q
What are the renal cortex, renal colums, and renal medulla?
A
Renal cortex:
- glomeruli located here
- create filtrate
Renal medulla:
- columns: extension of renal cortex into medulla
- renal pyramids
- renal papilla is where filtrate ends up and is collected by calices
8
Q
How do we produce urine?
A
- comes out of collecting duct of nephron from renal cortex
- collecting duct ends in papilla and drains into minor calyx, major calyx, then renal pelvis
- goes through ureter to the bladder
9
Q
What is a polycystic kidney?
A
- instead of being smooth on the surface, it has fluid filled sacs
- needs to be transplanted
10
Q
A
- infection can pass easily from one kidney to another
- hydronephrosis: built up fluid, swollen
11
Q
What are supernumerary renal arteries?
A
- 25% of major malformations in kids are urogenital
- 2 renal arteries on one side, 3 on the other
12
Q
What occurs in the renal tubule?
A
- renal corpuscle is the glomerular capsule and glomerulus
- glomerulus are tufted capillaries on inside
- to feed these, afferent arteriole brings in blood and an efferent arteriole leaving
- efferent arterioles spread through tubules
- proximal convoluted tubule
- loop of Henle which goes into medulla
- distal convoluted tubule (close to glomerulus)
- juxtaglomerular apparatus samples filtrate at distal convoluted tubule and if something is wrong, the amount of filtrate made by glomerulus is changed
- fluid goes out the collecting duct (can change amount of water in urine)
- past collecting duct, it is called urine because nothing else happens to it
13
Q
How much of the circulation goes to the kidney?
A
-20-25% of circulation goes directly to the kidney but the kidney is only 0.5-1% of body weight
14
Q
How much filtrate is made?
A
- from the 20-25% of blood flow, 180L is made into filtrate however the filtrate has virtually no protein or formed elements of the blood or any large molecules
- in the end, you only make about 1-2L of urine (about 99% of the fluid is reabsorbed)
- although the filtrate has lots of small molecules like glucose, amino acids, and bicarbonate ions, the urine has basically no protein, glucose, or bicarbonate
15
Q
What is the big picture of renal function?
A
- afferent arteriole blood goes in to renal corpuscle and through glomerulus
- blood goes out efferent arteriole through the peritubular capillaries
- filtration occurs at renal corpuscle (small things will get into filtrate, large things stuck in blood)
- reabsorption of material from the filtrate in the tubule to the blood
- in the renal tubule:
- reabsorption of material from the filtrate in the tubule to the blood
- secretion of material from peritubular capillaries into the filtrate
16
Q
What are the cell types in the juxtaglomerular apparatus?
A
- macula densa: part of distal convoluted tubule, “tasting” filtrate, make NO
- granular cells: make renin, have granules, if something is detected as wrong by the macula densa the amount of renin can be altered
- mesangial cells: some in JG apparatus and some in between the tufts of capillaries, important in regulating filtration, modified smooth muscle cells by contracting or relaxing
17
Q
A
18
Q
How does blood flow through the renal corpuscle?
A
- notice that the glomerular capsule is a continuous layer of tissue with the glomerular capillaries jammed into the centre
- the space between the visceral and parietal layer is the capsular space and that is where the filtrate is formed
- with each heart beat, blood is getting pumped through the glomerular capillaries which pushes filtrate out
19
Q
What structure is on a renal capillary? What is the structure of a renal capillary?
A
- fenestrated endothelium
- basal lamina (negatively charged from loose aggregations of collagen to act like a -ve charge filter to keep -vely charged proteins in the vascular space)
- podocyte
- has pedicels
- in between the pedicels of the podocytes are filtration slits
- filtrate must move from inside capillary through the fenestrae and filtration slits into the capsular space
20
Q
Describe the filtration process
A
- blood flowing through filtration slits into capsular space
- all small molecules can pass through capillary to capsular space
- large molecules ( > albumin size) cannot and stay in the blood
- as blood flows, 15-20% of plasma becomes the filtrate and the rest goes on to peritubular capillaries
21
Q
A
22
Q
The glomerular capillaries are involved in _____ while the peritubular capillaries are involved in _______.
A
filtration
absorption and secretion
23
Q
How do the kidneys and CV system work together?
A
- the CV system generates the pressure necessary for glomerular filtration and drives the high flow needed to maintain a stable cortical interstitial solute composition
- the kidneys maintain blood volume, regulate plasma osmolality, and secrete mediators that affect both cardiac performance and vascular tone
24
Q
Describe net filtration pressure
A
- pressure pushing fluid out of the glomerular capillaries (positive pressures):
- blood, hydrostatic pressure in capillaries (ie. the pressure of the blood in the glomerular capillaries)
- pressure holding fluid in the glomerular capillaries (negative pressures):
- capsular hydrostatic pressure (ie. the pressure of fluid already in the capsule)
- blood osmotic pressure (ie. the attraction of the dissolved materials in the blood for water)
- there is usually net positive pressure of 10mmHg
- this pressure pushes filtrate into the capsular space and this determines the glomerular filtration rate (GFR)
25
Describe renal autoregulation of the GFR
- the kidney itself can act to alter the GFR by autoregulation and we are normally trying to maintain a GFR
- the GFR is easily altered by changing the blood pressure in the glomerulus or the leakiness of the capillaries in the glomerulus
- the changes in the glomerulus pressure are done by the: myogenic mechanism, tubuloglomerular feedback
26
Describe the myogenic mechanism
-the smooth muscle of the afferent arteriole is stretched by the increase in blood pressure and afferent arteriole responds with constriction which decreases GFR
27
Describe the tubuloglomerular feedback
- the macula densa of the JG apparatus detects high amounts of filtrate flow (lots of water and Na/Cl flowing past)
- inhibits NO release which inhibits afferent arteriole dilation which decreases GFR
28
Which hormones regulate GFR?
-ANP (atrial natriuretic peptide) and angiotensin II
29
How does angiotensin II regulate BP
- angiotensin II usually decreases amount of GFR by constricting afferent arteriole and increases BP because it constricts systemic arterioles
- sympathetic stimulation also stimulates JG apparatus
- ACE inhibitors act against hypertension so you don't get angiotensin II being produced
30
How does renin regulate filtration
- symp stimulation increases renin release
- increased BP from more angiotensin II and more Na+ reuptake in tubules
- low BP increases renin release
31
How does ANP regulate BP
- distention of atrium of the heart leads to the release of ANP
- ANP relaxes mesangial cells between glomeural capillaries so that more fluid goes into capsule and have more filtration/urine
- increases sodium loss and relaxes afferent arteriole
- once the blood volume goes down, the pressure in the heart decreases and ANP is no longer secreted
- ANP increases GFR
32
What is neural regulation of GFR?
- the sympathetic branch of the ANS has inputs in muscular walls of the afferent arterioles
- receptors are alpha-1 adrenoceptors like most of the rest of the arterioles in the body
- with low blood flow, the glomerular hydrostatic pressure goes down and then filtration decreases
- once this happens there is spare blood to go to the muscles that are busy considering exit strategies and there is little urine being made at this time
33
What are functions of the kidneys?
- regulates blood ionic composition
- regulates blood pH
- regulates blood volume
- regulates BP (RAA pathway)
- maintains blood osmolarity (300mOsm/L)
- produces hormones (vit D, erythropoietin)
- regulates blood glucose
- excretes waste
