Renal Flashcards
what surrounds the kidneys
- layers after the kidney are:
- renal capsule
- perirenal fat
- renal fascia
- pararenal fat
the left kidney is slightly lower down than the right
T/F
False
the right is lower down due to being pushed by the kidney
what vertebral levels are the kidneys found at
T12 - L3
they are ~ 3 vertebrae in length
describe adrenal gland vasculature
- arteries x3
- superior artery = branch of the inferior phrenic artery
- middle artery = branch of the abdominal aorta
- inferior artery = branch of the renal artery
- one vein drains the gland = the adrenal vein
- the right adrenal vein drains directly into the IVC as its is in close proximity
- the left adrenal vein drains into the left renal vein first
describe the anatomy of the adrenal glands
- capsule
- cortex
- zona Glomerulosa
- mineraolcorticoids synthesis
- Zona Fascicularis
- Glucocorticoids synthesis
- Zona Reticularis
- androgens synthesis
- zona Glomerulosa
- medulla
- catecholamine synthesis
what doe the renal hilum contain
- renal vein
- renal artery
- lymphatics
- nerves
- ureters
describe the renal vasculature
- right and left renal arteries from the abdominal aorta
- right and left renal veins that drain directly into the IVC
- the right vein is shorter than the left
where do the right and left gonadal veins drain into
right drains directly into IVC
left drains into left renal vein first
Describe the anatomy of the internal kidney
- cortex around the outside
- medulla in the middle
- arranged into pyramids
- calyces
- minor calyces → major calyces → renal pelvis → ureter
what is a nephron
a functional unit of the kidney
how is the nephron arranged within the kidney - where do the separate structure lie
- the glomerulus, Bowman’s capsule, proximal and distal tubules and part of the collecting duct are in the cortex
- the loop of henle and the rest of the collecting duct are in the renal pyramids
what is the renal papilla and what is its function
the apex of the medulla
it is the opening into a minor calyx for outflow of urine
explain the pathway of the ureter
it passes from the kidney to the bladder and travels behind the numerous arteries including the uterine and ovarian arteries.
“water under the bridge”
urine is transported in the ureters by peristalsis
T/F
True
they have muscular walls
describe the passage of blood in the kidneys starting from the abdominal aorta
Abdominal aorta → renal artery → segmental arteries → interlobular arteries → arcuate arteries → afferent arteriole → Glomerulus → efferent arteriole → peritubular capillaries → interlobular veins → Arcuate vein → interlobular vein → renal vein → IVC
What are the functions of the kidney
A WET BED
- Acid/base balance
- Water removal
- Erythropoietin
- Toxins
- Blood Pressure
- Electrolyte
- D - vitamin D activation
how much of the cardiac output goes to the kidneys
20%
what is glomerular filtration rate
The volume of fluid filtered through the from the glomerulus to the bowman’s space
Glomerulus = the collection of capillaries carrying blood to filtered
bowman’s capsule = the space into which filtrate is captured
what makes up the filtration barrier
- fenestrated endothelium
- basement membrane
- podocytes
GFR value
125ml/min in an average 70kg person
equation for GFR calculation
GFR = KF (PGC-PBS-πGC)
- KF – filtration coeffiecnt
- PGC – hydrostatic pressure of glomerular capillaries
- PBS – Hydrostatic pressure of bowman’s space
- πGC – Oncotic pressure of glomerular capillaries
why is there no oncotic pressure of the Bowmas capsule
there are no proteins in bowmans space
why is creatinine used as a marker substance
- it’s freely filtered
- not secreted or reabsorbed
- not metabolised
what factors affect GFR
- Pressure
- Size of the molecule
- Charge of the molecule
- Blood flow
- Binding to plasma proteins
describe the physiology of glomerular filtration and urine production
- the glomerular capillaries are fenestrated, meaning they have gaps to allow molecules in the blood to be filtered out, everything except RBCs.
- the endothelial cells have glycocaelyx - proteins - which are -vely charged to repel the passage of proteins [also -vely charged] through.
- the afferent arteriole dilates while the efferent one constricts which raises the hydrostatic pressure exerted on the blood in the glomerulus → ultrafiltration.
- the filtrate passes into Bowman’s capsule and is basically protein free plasma.
- as the filtrate moves through the tubules, certain substances are reabsorbed either by diffusion or by mediated transport[ATP]
- whats left enters the collecting duct into the calyces to form the urine
how is GFR controlled
- To increase GFR;
- Constrict the efferent arteriole (build up pressure before)•Dilate the afferent arteriole (builds up pressure after)
- To decrease GFR;
- Constrict the afferent arteriole (reduce blow flow)•Dilate the efferent arteriole (allows blood to escape easier)
what is the glomerular filter layers made of
- fenestrated endothelial cells
- basement membrane
- made from fusion of capillary and podocyte basement membrane.
- podocytes
what is the glomerular filter layers made of
- fenestrated endothelial cells
- basement membrane
- made from fusion of capillary and podocyte basement membrane.
- podocytes
what is autoregulation in the kidneys and why is it important
Pressure within afferent arteriole rises → stretches vessel wall → triggers contraction of smooth muscle → arteriolar constriction
- important because it prevents a rise in systemic arterial pressure reaching the capillaries in the nephron THUS it prevents damage and maintains constant level of filtration
- revers happens in low pressure to maintain a constant rate of filtration
what are the mechanisms of autoregulation within the glomerulus
- Myogenic; smooth muscle contraction in response to external stretching force, occurs in capillary walls, passive mechanism
-
Tubuloglomerular feedback;
- constriction of afferent arteriole to increased sodium chloride concentration.
- Dilation in response to decreased concentration.
- Fast response via GFR and slow via RAAS
explain tubuloglomerular feedback
- GFR of individual nephron regulated by the rate at which filtered fluid reaches the distal tubule
- Cells of macula densa (distal tubule) detect NaCl arrival
- Macular densa cells release prostaglandins in response to reduced NaCl delivery.
- This acts on granular cells, triggering renin release, activating the renin-angiotensin system
protein is never found in the urine
T/F
False
- The only protein that is normally found in urine is Tamm– Horsfall protein (uromodulin) which is produced by the thick ascending limb
- otherwise other proteins shouldnt be present in the urine and indicate leaky nephrons
what is the filtration fraction
- Filtration Fraction = GFR / Renal Plasma Flow
- i.e. the proportion that gets filtered.
what is renal clearance
renal clearance is the volume of plasma completely cleared of a substance by the kidneys per unit time.
main function of the proximal tubule
-
bulk reabsorption of essentials:
- Na+
- Cl-
- water
- glucose
- bicarbonate
- amino acids
- phosphate
- lactate
- ⅔ of all filtrate reabsorbed here