Renal System Flashcards
(31 cards)
1
Q
The kidney
A
- situated within deep tissue behind the peritoneum for protection
- partially protected by lower ribs
- delicate organ that requires protection from traumatic damage
2
Q
Protective layers
A
- kidney encapsulated in the renal capsule providing protection and maintains shape
- second adipose capsule consists of fatty tissue providing protection and holds it in place within abdomen
- outer renal fascia, fibrous tissue securing kidnet to other structures
3
Q
External anatomy
A
- average size 10-12cm long
- renal hilus provides exit for ureter abd entry point for renal artery and renal vein
- nerves and lymphatic ducts also enter an exit through the renal hilus
4
Q
Internal anatomy
A
- superficial layer called renal cortex which houses blood vessels and portions of the nephron
- depper area called renal medulla which as 8-18 pyramid structures called renal pyramids
- the points face centre of the kidney into minor calyx
- urine produced by the nephron drains into the minor calyx
- these drain into the major calyx which lead to renal pelvis
- from here urine is drained through the ureters into the urinary bladder
5
Q
Blood and nerve supply
A
- kidneys receive 1200 mls/min of blood for filtration via renal artery
- this divides into interlobar arteries that branch out between the renal pyramids
- these further divide into afferent arteriole which supplies each nephron
- forming vasa recta which surrounds each nephron
- renal plexus nerves supply the kidney (part of SNS) and surround the blood vessels that supply the kidney
- vasomotor nerves control the diameter of these blood vessels aiming to maintain flow and pressure
6
Q
Path of blood flow
A
- renal artery
- segmental arteries
- interlobar arteries
- arcuate arteries
- interlobular arteries
- afferent arterioles
- glomelular capillaries
- efferent arterioles
- peritubular capillaries
- interlobular veins
- arcuate veins
- interlobar veins
- renal vein
7
Q
Structure of a nephron
A
- bowman’s capsule
- glomerulus
- proximal tubule
- distal tubule
- collecting duct
- loop of henle with capillary network
- branch of renal vein
- arteriole from glomerulus and renal artery
8
Q
Nephrons
A
- approx 2 million in renal system
- site of blood filtration and urine production
- also ply role in blood pressure control
- cannot regenerate if damaged by trauma or infection
9
Q
Filtration
A
- kidneys essentially filter the blood and maintain the normal balance of solutes within the blood
- these are:
sodium
potassium
calcium
chloride
urea
creatinine
10
Q
Sodium (Na+)
A
- norm 135-145 mmol/L
- involved in all nervous impulses
- can influence the movement of water by osmosis
- role in transporting substances across cell
11
Q
Potassium (K+)
A
- norm 3.5-5.0 mmol/L
- also involved in nerve impulses
- transport of sustances across cell membranes
12
Q
Calcium (Ca2+)
A
- norm 2.12-2.65 mmol/L
- involved in muscle contraction
- essential in ensuring normal cardiac contraction
- also plays part in bone formation
13
Q
Chloride (Cl-)
A
- norm 95-105 mmol/L
- involved in movement of ions between fluid compartments
14
Q
urea
A
- norm 2.5-6.6 mmol/L
- ammonia by product of metabolism
- high hyrdogen content
- converted to urea by liver
- excreted in urine
15
Q
creatinine
A
- norm 70-150 mmol/L
-waste product of protein metabolism - secreted unchanged via renal system
16
Q
Renal corpuscle
A
- two components: glomerulus and bowmans capsule
- glo is the capillary network that sits within the bowmans capsule
- water and solutes from the blood passing through thr glo is collected in the glomerular space
- afferent art that enters the glo network is wider than the efferent arteriole that exits
- this produces back pressure within the glo enabling filtration
- filtered fluid from the bowmans drains into the proximal convulted tubule (PCT)
17
Q
Glomerular filtration
A
- efferent arterioles have a smaller diamter than afferent arterioles
- causes an increase in pressure in glo
- fluid and small solutes are pushed through the membrane under pressure
- this filtered fluid is called glomerular filtrate
- 180L produced daily
- 178L returns to blood stream
- remaining fluid is urine
- constant pressure required for this to maintain homeostasis
- variations can be compensated
18
Q
Renal tubules
A
- this is where the majority of water and solutes is reabsorbed into the body
- the loop of henle connects the PCT to the distal convulated tubule (DCT)
- from here the fluid flows into the collecting duct and drains into the renal pelvis
19
Q
Tubular reasbsorbtion
A
- fluid that is generated in the bowmans is rich in, na, k, cl, ca2, hco3
- blood homeostasis demands that some are reabsorbed into the blood stream and some excreted into urine
- majority occurs in PCT
- high degree of microvilli on cells to facilitate absorption
- high levels of water and na reabsorbed either by osmosis or active transport using ATP
- excess H and K are excreted to maintain homeostatsis
- majority of this occures in the PCT
20
Q
Tubular reabsorbtion (PCT)
A
- 100% of amino acids and glucose is reabsorbed in PCT
- 80-90% of HCO
-65% water, na, and k - 50% of cl- and urea
- figures represent % of solutes in filtrate
21
Q
Reabsorbtion at the loop of henle
(LH)
A
- responsible for the fine tuning of reabsorbtion
- fluid here has a different chemical composition to blood
- reabsorbtion as follows
K+ 30%
na+ 20%
cl- 35%
h2o 15%
22
Q
loop of henle
A
- water reabsorption related to solutes so the concentration of urine can be controlled
- water only reabsorbed in descending limb
- solutes in ascending limb which is impermeable to water
- this creates osmotic pressure
23
Q
What is osmosis
A
a process whereby water moves form an area of low
solute concentration to an area of high concentration across a semi-
permeable membrane
24
Q
Collecting duct & antidiuretic hormone (ADH)
A
Antidiuretic hormone (ADH) secreted by the pituitary gland
stimulates retention of water by increasing the permeability of
the collecting duct to water
Achieved by stimulating the synthesis of aquaporin channels,
which facilitate diffusion of water
Alcohol inhibits ADH secretion so that’s why you pee when
drinking!
25
Concentrated urine production
During low water intake or high perspiration
The solute concentration of the filtrate is increased
Water is reabsorbed due to high ADH
Producing concentrated urine
26
Dilute urine production
Excess fluid intake/volume reduces ADH secretion
Therefore, the distal collecting tubule remains impermeable
to water
Solutes continue to be reabsorbed and secreted
Resulting in large volumes of urine with low concentration of
solutes per litre
27
Tubular secretion
Waste products, excess nutrients and water are secreted by the
kidneys in urine
These include:
◼ Hydrogen (H+)
◼ K+
◼ NH4+ (ammonium)
◼ Some drugs (e.g. penicillin)
28
Hyrdogen secretion
Essential to maintain plasma pH: 7.35-7.45
Hydrogen acid producing
H+ + H2O → H2CO3 (carbonic acid)
H+ is excreted in the urine
HCO3- is reabsorbed to buffer the effects of H+
New HCO3- is produced
29
renal calculi (stones)
Patients complain of:
Flank and/or groin pain
(renal pelvis)
Lower abdo pain
(midureter)
Urgency, frequency,
incontinence (lower
ureter)
Pain may cause N&V
Haematuria of varying
severity
Can lead to hydronephroisis
30
hydronephrosis
Dilation of renal pelvis due to
downstream obstruction
This increased pressure causes
mechanical damage to
nephrons and increases
collagen deposition
Normal process of repair,
however imbalance of growth
and repair causes loss of
nephrons
31
blood pressure control and hydration
Juxtaglomerular apparatus situated in the DCT
Section of the DCT in contact with afferent arteriole
These cells will detect changes in filtrate solutes and stretch of
vessel wall
Compensate by influencing blood pressure through renin-
angiotensin-aldosterone system
