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
Q
Describe renal autoregulation of the GFR
A
- 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
Q
Describe the myogenic mechanism
A
-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
Q
Describe the tubuloglomerular feedback
A
- 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
Q
Which hormones regulate GFR?
A
-ANP (atrial natriuretic peptide) and angiotensin II
29
Q
How does angiotensin II regulate BP
A
- 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
Q
How does renin regulate filtration
A
- symp stimulation increases renin release
- increased BP from more angiotensin II and more Na+ reuptake in tubules
- low BP increases renin release
31
Q
How does ANP regulate BP
A
- 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
Q
What is neural regulation of GFR?
A
- 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
Q
What are functions of the kidneys?
A
- 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
