Renal Structure And Function Flashcards
How much urine does a human produce in 24 hours
1..5 litres
What 2 factors may decrease renal excretion of fluid
Increased sweating
Respiration
What is the approximate weight of the kidney
130-150g
What is the kidney surrounded by
Protective tissue capsule
Where is blood filtered
In the cortex
What does the medulla contain
Nephrons and where urine is produced
What are the 3 supportive tissue layers surrounding the kidney
Renal capsule - deep
Adipose tissue - middle
Renal fascia - superficial
Where is the hilum area in the kidney
On the concave surface shape
What happens at the hilum in the kidney
Renal artery, renal vein nerve and ureter enter/leave
What are the 3 internal regions of the kidney
Cortex
Medulla
Pelvis
What are the 4 structures internally of the kidney
Renal column
Renal pyramid
Papilla
Minor/major calyx
What is the blood supply to the kidney
Renal artery
Renal vein
What are 5 excretion products from the kidneys
Urea
Uric acid
Creatinine
End products of haemoglobin breakdown
Drugs and food additives
What are the 3 main processes which enable the kidney to filter blood
Glomerular filtration
Tubular reabsorption
Tubular secretion
What vessel brings blood into the glomerulus
The afferent arteriole
What vessel carries the rest of the blood out that hasn’t been filtered by the glomerulus
The efferent arteriole
What is the glomerulus composed of
A web of arterioles and capillaries
What are the 4 main functions of the kidney
Filtration
Reabsorption
Secretion
Excretion
What are the 3 major layers within the capillary
Endothelium
Basement membrane
Podocytes
What 3 aspects does the bowman’s capsule contain
An innermost fenestrated vascular endothelium
The glomerular basement membrane
Podocyte cells layer
What are the 4 main components of the glomerular basement membrane
Type IV collagen
Laminin
Nidogen
Proteoglycans
Where are podocytes found
Wrapped around the capillaries of the glomerulus
What do podocytes do
Assist the glomerulus to act as a sieve facilitating the formation of an ultrafiltrate
- small molecules into nephron
- larger molecules retained in blood
What type of epithelium are podocytes
Visceral epithelial cells (specialised epithelial cells)
What is the glomerular filtration rate (GFR)
Describes the flow rate of filtered fluid through the kidney
What is the GFR equation
The glomerular permeability x net filtration pressure
What is the equation to find out the permeability of the capillary
GFR/net filtration pressure
What is the cause of afferent arteriolar constriction
Low GFR
Low RBF
low Pgc
What is afferent arteriolar constriction due to
Renin/adenosine
What is the cause of efferent arteriolar constriction
Increased GFR and Pgc and decreased renal blood flow
What is the efferent arteriolar constriction due to
ANG II
What is the cause of efferent arteriolar dilation
Decreased GFR and Pgc and increased RBF
What is efferent arteriolar dilation due to
Parasympathetic activation
How does low GFRs impact the body
The ability to excrete drugs
What are tubules in the kidney lined by
Columnar epithelial cells with micro villi
What does the proximal convoluted tubule do
Reabsorbs molecules filtered in the glomeruli allows the conservation of protein and vital molecules
What percentage of molecules does the PCT reabsorb
70-80%
What is the descending limb loop of henle permeable to
Water
Mostly thinner
What is the ascending limb loop of henle permeable to
Ions
Mostly thicker
After the loop of henle what solution does it leave behind
A dilute, hypotonic urine but hypertonic interstitial fluid
What is the juxta-glomerular apparatus
A region where the distal convoluted tubule lies against the afferent arteriole feeding the glomerulus
What do juxtaglomerular cells do
Produce renin and act as mechanoreceptors - sense arteriolar blood pressure
What is macula densa
Distal tubule cells which act as chemoreceptors/osmoreceptors respond to change in sodium concentration stimulates JG cells to release renin when they detect a drop in chloride concentration
What happens at the distal convoluted tubule
Fine tuning of tubular resorption
Important role in acid base balance
What is the collecting duct impermeable to
Water but becomes permeable in response to ADH
What is the lower region of the collecting duct permeable to
Urea allowing some reabsorption maintaining high ion concentration
What type of of urine passes on to the bladder
Hypertonic
What affect does aldosterone have on the kidney
Cells of the cortical collecting tubules
Stimulated Na/K - ATPase and increase NA reabsorption and K secretion
What affect does angiotensin II have on the kidney
Promotes NA rention
Stimulates aldosterone
Constricts efferent arterioles
Reduces peritubular capillary hydrostatic pressure
Stimulates NA/K-ATPase in the PCT, loop of henle, DCT and collecting tubes
What affect does antidiuretic hormone have on the kidney
Controls water reabsorption/excretion
Increases water permeability of DCT and collecting tubules
Increases permeability to urea in the medullary collecting tubule
Helps conserve water during dehydration
What 3 hormones control of Ca2+ metabolism on the kidney
PTH
1.25 dihydroxycholecalciferol
Calcitonin
What affect does natriuretic peptides have on the kidney
Produced by cardiac cells
Promote Na secretion in the collecting duct
What are the 3 composed layers of the ureter
Inner mucosa
Muscular layer
Adventitia
What forces urine to travel through the renal pelvis
Perisaltic waves force urine to the ureters
Distension of the ureters stimulate their contraction propelling urine to the bladder
What are the 3 consisting in the bladder
Mucosa
Muscular layer
Fibrous adventitia
How much urine can the bladder hold
500-600 ml
What epithelium is the urethra
Pseudostratified columnar epithelium
What is the internal urethral sphincter composed of
Smooth muscle
What is the external urethral sphincter composed of
Skeletal muscle
