ILA9 - Renal Flashcards
What are the layers surrounding the kindney? (deep to superficial)
Renal capsule (tough), perirenal fat, renal fascia, pararenal fat
Name some functions of the kidney.
- Filter and excrete waste from the blood (metabolic waste, water and xs electrolytes)
- Maintain H2O and electrolyte balance
What is the position of the kidneys?
Retroperitoneal
Left T12-L1
Right L1-L3 (due to liver)
What are the layers of the kidney (deep to superficial)?
Pelvis, medulla, cortex
Describe the renal cortex.
- Roughly 7mm in healthy adult
- Composed of renal corpuscles (filtering part), PCTs and DCTs
- Medullary ray= collection of L of Hs and collecting ducts which have corpuscles in outer part of cortex, give striated appearance
Describe the renal medulla.
- Around 20 inverted pyramids (papilla is the tip)
- Drain into calicies then into pelvis
- Contains L of Hs, CDs and blood vessels (vasa recta)
Describe the renal pelvis.
- Contains fat, urine collecting system
- Urothelium
- Continuous with CDs and ureters
Describe the course of the ureters.
Retroperitoneal. Renal pelvis, run along ant. surface of psoas muscle, passes under uterine artery and vas (water under the bridge), cross sacroiliac joint and pelvic ridge, at iliac spine they angle towards the bladder
What is the supply to the ureters?
in abdomen it is renal and gonadal arteries
In pelvis it is superior and inferior visceral
Venous drainage is identical
What is the nerve supply to the ureters?
Testicular, renal and hypogastric nerve plexus
What are the parts of the bladder?
- Apex (superior part, near pubic symphysis)
- Body (main part)
- Fundus (main part)
- Neck (bladder to ureter)
What is the trigone in the bladder?
The bit between the openings of the urters and the ureter (triangle shape), it is the only part of the inner surface which is not trabeculated
What type of mucosa is in the bladder?
Rugose, urothelium
What is the function of the bladder?
Collection, temporary storage and expulsion of the urine
What is the blood supply to the bladder?
Internal iliac
What controls the outflow of urine from the baldder?
Internal and external urethral sphincters
What muscle is in the wall of the bladder?
Smooth (detrusor), has sympathetic and para. innervation
What is the innervation to the bladder?
- Sympathetic: hypogastic (T12-L2) relaxes detrusor
- Parasympathetic: pelvic (S2-4) contracts detrusor
- Somatic: pudendal (S2-4) external sphincter
How long is male & female urethra?
Male = 15-20cm Female = 4-5 cm
What are the parts of the male urethra?
1) Pre-prostatic
- int urethral orifice ends at prostate, urothelium
2) Prostatic
- through prostate gland, urothelium
3) Membranous
- ext urethral sphincter (voluntarty control), urothelium
4) Penile/spongy
- corpra spongiosa, navicula fossa, pseudo then stratified squamous
Where does the urethra open in females?
Between the labia minora, anterior to the vagina
What are the two types of nephron?
Juxtamedullary and corticular
What is the order of the renal tract?
Pelvis, ureter (uteropelvic junction), bladder (forming valves), urethra, pee pee
What is the type of muscle in the urethral sphincters in males and females?
Male- internal is smooth, external is skeletal
Female- internal isnt functional, external is skeletal
Which substances are mainly excreted/reabsorbed at the PCT, desc. limb of LoH, asc. limb of LoH, DCT and CD?
PCT- glucose,AA,H20 and salts reabsorbed, drugs and poisions exreted
Desc- H2O reabsorbed
Asc- salts reabsrobed
DCT- salts, Ca and H2O reabsorbed. K, H and urea exreted
CD- H20 reabsorbed
Describe the corpuscle?
a) Glomerulus= tuft of capillaries from afferent arteriole
b) Bowman’s capsule is double walled
c) Capillary tuft supported by Mesangial cells (smooth muscle)
- produce extracellular matrix protein
- reg of GFR,
- phagocytosis
d) Filtration barrier
- capillary endothelium fenestrated (covered by fibrils)
- basement memb is double and has -ive charge
- podocyte foot processes (-ive charge)
e) Juxtaglomerular apparatus (2 cell types)
What are the 2 cell types in the juxtaglomerular apparatus?
a) Juxtaglomerular cells (granular)
- endothelial cells of afferent arteriole expanded
- detect changes in bp, decreased leads to secreted renin to increase water reabsorption and so increase bp
b) Macula densa
- Detect changes in Na+ in the DCT
- lie between the DCT and corpuscle
- uses amount of Na in DCT as indication for GFR, if drops it decreases resistance in afferent arteriole also signals to juxtaglomerular cells using prostaglandin to secrete renin
Describe the PCT.
- Cuboidal epithelium with microvilli = increased surface area
- Many mitochondria for active transport of Na+&K+ back in
- Lysosomes which breakdown absorbed proteins
- Na/K ATPase pumps Na in, water follows
Describe the LoH.
a) Desc. limb (thin, H2O permeable)- H2O reabsorb= concentrate urine (osmosis)
b) Asc. limb (thick, impermeable to H2O)- reabsorb salts by AT, leaves waste and H2O in tubules
c) Countercurrent multiplication
- desc limb, osmolality in filtrate increases due to H2) leaving, impermeable to salts (osmolality 200 to 1200)
- asc limb, Na reabsorbed by diffusion and active transport
What is the order of blood flow in the kidney?
Renal artery, segmental, interlobar, arcuate, interlobular, afferent arterioles (peritubular capillaries and vasa recta), glomerular capillaries, efferent arteriole, interlobular veins, arcuate veins, interlobar veins, segmental veins and then renal vein
Describe DCT.
- Cuboidal, no microvilli, cells are shorter than PCT
- Distal end drains into papillae and calicies
- Cells:a)principle (responds to aldosterone=Na for K, responds to ADH = increased aquaporin 2)
b) intercalated (H+ for HCO3-)
What is the hydrostatic pressure in the glomerulus and bowman’s space?
45mmHg and 10mmHg meaning forces solutes out
What is the osmotic pressure in the glomerulus and bowman’s space?
25mmHh (rises) and 0 meaning fluid drawn out
What is the rough Cardiac output? How much of that goes to the kidneys? How much urine is produced in a minute by the kidneys?
5L/min, 1L/min and 1mL/min
What are the volume sensors and where are they?
a) Baroceptors (aorta and carotid sinus)
b) Low pressure (aorta and pulmonary veins)
c) Afferent arteriole pressure and distension
d) Juxtaglomerular apparatus
- Juxtaglomerular cells and macula densa
How does renin bring about a change in BP?
1) Decreased H2O in ECF= decreased circulating vol = decreased renal flow, this is detected by the stretch receptors in the renal vascular walls
2) Renin is secreted from juxta. cells (renin is a proteolytic enzyme)
3) Renin is released to the afferent arteriole cells
4) Renin converts Angiotensinogen to Angiotensin I
5) Angiotensin I to Angiotensin II by ACE in lung
6) Angiotensin II causes vasoconstriction, aldosterone release from adrenal medulla, Na+ reabsorption in PCT, thirst and increased ADH
Describe the action of aldosterone on cytoplasmic receptors.
- Translocated to nucleus where acts as transcription factor
- Causes increased synthesis of epithelial Na+ channels (ENaC) and Na/K ATPase channels
- H2O moves with Na+ into cell (principal) and blood
Describe the action of aldosterone on cell membrane receptors.
Increases the number of open ENaC
So more Na+ into blood and more H2O
Where is ADH (vasopressin) synthesised?
Supraoptic and paraventricular nuclei of hypothalamus
Where is ADH secreted?
Posterior pituitary
How is ADH secretion controlled?
1) Mainly by hypothalamic osmoreceptors
- low water conc in blood (high osmolality) means water moves out of receptors = shrinkage= stimulation to post pituitary to release ADH= increased water reabsorption
2) Inputs from baroreceptors and Angiotensin II which override osmolality
Describe what happens when dehydrated.
1) Dehydration sense by osmoreceptors
2) Impulse to post pituitary causing ADH release
3) ADH binds to adenyl cyclase coupled Vasopressin 2 receptors in collecting duct
4) This causes:
- activation of cAMP
- activation of phosphate kinase
- increased transcription and insertion of aquaporin 2 to apical membrane
- increased thirst
What is the limiting factor in the production of angiotensin II?
Rate of production of renin
What is acute kidney injury (AKI)?
- Abrupt loss of kidney function which develops within 7 days
- Damage to kidney caused by decreased renal blood flow (renal-ischaemia) from any cause, exposure to harmful substances, inflammatory process within the kidney or obstruction of the urinary tract
What are the three categories of causes of AKI?
Pre renal, renal and post renal
Name some pre-renal causes of AKI.
Anything that decreases the blood flow to the kidney
E.g. low blood volume, low blood pressure, heart failure, damage to vessels supplying the kidneys, liver cirrhosis
Name some renal causes of AKI.
- Damage to the kidney
- Inflammation
- PKD
Name some post-renal causes of AKI.
- Obstruction of tract
- Kidney stones
- Enlarged prostate
- Blood clots
Name some common causes of chronic renal failure.
- Conditions that put strain on the kidneys
- High BP damages the capillaries
- Diabetes (glucose damages the filters)
- Inflammation
- Polycystic kidney disease
List some complications of chronic renal failure.
Anemia, weak immune system, increased cardiovascular disease risk, CNS damage, metabolic acidosis, myoclanic twitching, weak bones
What effect do ACE inhibitors have on the kidneys?
- efferent arteriole dilation= reduced GFR
- reduced aldosterone= increased exretion of Na and water & increased reabsorption of K
