11.2 Lab + Lecture Notes Flashcards
Glomeruli
= circular, largely basophilic structures
- always found within the cortex
- use them to segment slide into cortex, medulla, sinus regions
what does Unperfused tissue mean
= vascular space filled with blood
Transitional epithelium will be seen where in kidney
- major + minor calyces
- ureter = thickest
what are Medullary Rays
- comprised of collecting ducts that travel radially towards the medullary pyramid
- define center of the cortical lobules
What are ducts of Bellini
= largest collecting duct as it exits medullary pyramid
- recognize it primarily by its location
- only nephric tubule near there is the thin tubule
- only capillary near that will be the vasa recta
PTCP
= systemic capillary bed supplying the cortex
Vasa Recta
= systemic capillary bed supplying the medulla
What are three things in the kidney you can label primarily by location
- thin tubules
- vasa recta
- ducts of Bellini
To identify a collecting duct in cortex
- use location + morphology
- look for medullary rays
- contains 2 types of cells
1) principle cells
2) Intercalated cells (5-10%) - contain higher density of mitochondria than principle cells
Compare the morphology of the PCT to the DT
- highly eosinophilic
- basal enfoldings
- cells should be larger (fewer nuclei within a given profile
- prominent brush border (microvilli) + glycocalyx
- since it is larger there will be more profiles ~ 7:1 ratio
Compare the morphology of the thick descending tubule to the think ascending tubule
- thick descending (like PCT)
- thick ascending (like DT)
- can’t use frequency of occurrence in the medulla though because it is closer to 1:1 ratio
What are the 4 cell types within the renal corpuscle and where will you find each
1) Epithelial Cells of parietal layer of bowman’s capsule = simple squamous epithelium (outside of bag)
2) Podocyte = visceral layer of Bowman’s capsule - poke into the urinary space, have relatively condensed nucleus
3) Capillary endothelial cell = squamous cell inside of glomerulus, poke inward towards capillary lumen
4) intraglomerular mesangial cell = round/cuboidal cell, euchromatic nucleus
What elements comprise the juxtaglomerular apparatus
1) Macula Densa
2) JG cells
3) Extraglomerular mesangial cells
What is the urinary pole of renal corpuscle
= where urinary space drains into a PCT
What are the components of the urinary system
1) Kidneys
- produce urine as filtrate of the blood
2) ureters
- tube the connects each kidney to the bladder
3) bladder
- stores urine until voiding
4) uretra
- tube the connects bladder to external environment
Describe the anatomy of the kidney
- each kidney is composed of lobes (with medulla at center surrounded by cortex)
- renal artery/vein give blood to/from the kidney
- urine is conveyed from minor calyx –> major calyx –> leaves kidney via ureter
- medulla = completely surrounded by minor calyx
- hilar = generic term describing region of indentation in kidney bean space
What is the location of the kidney
= retroperitoneal organ
- have dense CT compartment surrounding whole organ (adipose tissue in this CT)
- adrenal gland sits above it
Describe the FXN of the kidney
= filter blood - steps:
1) everything we could possible want removed is removed
- function of glomerular filtration barrier
- produces ultrafiltrate
2) somethings are selectively reabsorbed into circulation
- function of nephron + collecting ducts
- substance as it is being modified = filtrate
3) urine = end product
Describe the function of a nephron
= take everything out of blood + selectively reabsorb A) PCT - takes glucose (+ other lg. molecules) back - puts it into CT --> then back to blood B) descending parts = just water C) ascending parts = just salt D) collecting ducts = differential water resorption - hormonally dependent
What are the 4 basic morphologies of the kidney based on their function - include the relevant parts of the nephron and any functional ultrastructures that are important
1) Active resorption of water salts, especially small molecules
- PCT, PST, Thick descending
- basal striations, microvilli
2) Passive resorption of water
- thin loops
- squamous shaped cells?
3) Active salt transport + control of interstitial osmolarity
- Thick ascending, DST, DCT (DTs)
- basal striations
4) Active modification
- hormonally controlled
- collecting ducts/tubules
- cuboidal cells
Describe how 3 separate embryonic tissues contribute to the functional units of the adult kidney
1) mesonephros
- collecting tubule, collecting duct, calycies, ureter
- development of the collecting duct = the first tubular structure derived from CT
2) Metanephros
- loop of Henle & nephron (from metanephric tissue cap
- 2nd tubular epithelial structure being derived from CT
3) Endothelium
- glomerulus (descending artery)
- lined by visceral epithelium
- parietal layer of renal corpuscle (bowman’s capsule) –> between 2 epithelia = double thick BM = site of blood filtration
When does the induction of the nephron occur
= at week 23
- presence of nephric tubule (collecting tubule)
- -> induces formation of nephron out of mesenchymal tissue
Describe the kidney lobule organizational development
= overal = metanephric derived-tissue –> is centered around mesonephric derived tissue
1) In cortex
A) mesonephric derived center = collecting ducts (in medullary rays - cortical structure containing colelcting ducts that organize the cortex into lobules)
B) Metanephric derived exterior = renal corpuscles, PCTs, DTs
2) In medulla
A) mesonephric derived center = descending collecting ducts
B) metanephric derived exterior = thick descending limb; thin limb; thick ascending limb
Describe the kidney’s blood supply
- segmental artery = useful for surgeons because allow controlled blood supply to 1+ desired lobes of kidney only
- kidney weighs 5% of body weight –> but receives 25% of cardiac output
- kidney receives 1L/min of blood
- only produces 1 ml/min of urine
Describe the kidney’s innervation + lymphatic drainage
- lymphatic drainage is primarily through hills (arcuate lymphatics < interlobular lymphatics< hilar lymphatics)
- also is minor capsulary lymphatic drainage (sub capsular + capsular lymphatics)
- the vascular elements are heavily innervated with sympa fibers
- nephrons are lightly innervated
- -> nerves follow the vessels
What is a glomerular capillary tuft
- exists on anastomosing capillary pathway (amount of glomerular capillaries the get blood vs. use anastomosing path is controlled by cells/hormones
- if GFR is low = blood will move from A–>E quickly (use anastomose)
- if GFR is high = blood will go through all capillaries
what is the function of Mesangial Cells
- can change perfusion through glomerular capillary tuft
- 2 types of extra/intra - glomerular mesangial cells
- modulate glomerular filtration by contraction
- generate + respond to vasoconstrictors/dilators
Describe the juxtaglomerular apparatus / vascular pole
- 3 specializations
1) Macular dense
2) JG cells
3) Mesangial cells - glomerulus = filtration portion of the JGA
Describe the macula densa
= localized near afferent arteriole
- monitors [NaCl] in DCT + regulates renin secretion = specilization of DCT
= cells in DCT that are closest to glomeruli - have larger nuclei + are tightly packed = specialized sensory cells
- FXN = communicate info to rest of JGA about filtrate –> influence renin secretion
Describe the JG cells
= specialization of smooth muscle cells of arteriole wall proximal to JGA
- specialized to produce/secrete renin
- contain renin granules
- form the “tunica media” of arterioles
Describe the mesangial cells
- function = phagocytose debris + provide structural support to BM + secrete molecules in response to glomerular injury
= modified smooth muscle cells - primarily located in CT compartment of JGA
- 2 types
1) extraglomerular mesangial cells
2) intraglomerular mesangial cells
Describe the secretion of renin
- controlled by 3 things
1) fluid in distal tubule (sensed by macula densa)
2) pressure in arterioles
3) sympathetic never fibers near JG cells
Describe the cortical glomerulus
- (75%) of glomeruli
- contacts “cortical nephron” - reaches only outer medulla
- contributes blood to PTCP
- PTCP = peritubular capillary plexus = capillary bed in cortex - drains either to interlobular veins or 1st to stellate veins then interlobular veins
Describe the juxtamedullary glomerulus
- (25%) fo glomeruli
- contacts the “juxtamedullary nephron” - travels to inner medulla
- contributes blood to vasa recta
- vasa recta = capillary bed in medulla - returns to juxtamedullar region to drain to interlobular veins or arcutate veins
Describe the renal cortical interstitium
- interstitial tissue = 10% of cortex - has lower salt content (300mOsm) - collagen type I and III fibers + fibronectin
- cortical interstitial cells
A) fibroblast-like cells –> secrete EPO
B) lymphocyte-like cells –> prob APCs
Describe the renal medullary interstitium
- interstitial tissue = 40% (much more than in cortex) of the tissue in medulla - has high osmolatiry (blood in the vasa recta can be up to 1500mOsm) - the thick ascending gets this up
- medullary interstitial cells
A) fibroblast-like cells - prominent lipid droplets
- synthesize prostaglandins
- change appearance with diuretic state
B) lymphocyte-like cells
C) pericytes
Describe the hormonal influence/production in the kidneys
A) water influences
- secretes ADH
B) salt influence
- Aldosterone (from adrenal cortex) - removes Na & add K to lumen
- ANP (myocytes in hear) - add Na to urine
- PTH - promotes PO4 excretion + Ca absorption
–>produces vitamin D (increases Ca + PO4 absorption from gut)
C) blood pressure influence
- produces EPO (interstitial cells in cortex + medulla) - controls RBC hematopoeisis
- JG cells - release renin (response to perfusion pressure or sympa stim) increases BP
- Medullary interstitial cells - produces prostaglandins (vasodepressor)
Describe kidney and blood filtration
- all you need is fenestrated capillary, permeable epithelium, lumen with osmotic gradient
- 2 types of renal dialysis
1) Hemodialysis - blood passes along filtration membrane which draws out waste via an osmotic gradient
2) peritoneal dialysis - fluid is added to peritoneal space via catheter
- drained after few hrs.
- uses peritoneal wall as natural semi-permiable membrane
Describe diabetes mellitus in relation to the PCT
- diabetes mellitus = leading cause of kidney disease - increase glucose overworks PCT –> can clog BM (mesangial cells cannot keep up with clearance)
- in adequate insulin production by pancreas (type I) -
- or inadequate response of insulin receptors (type II) –> increases blood glucose
- all glucose is put into filtrate (as usual) but not all can be reabsorbed by PCT
- glucose lost in urine with water in efferent to balance glucose overload = why get thirst symptom
Describe diabetes mellitus WRT glomerular BM
- chronic high glucose in ultrafiltrate - damages the BM (album + other proteins can escape and get into filtrate and eventually lost in urine)
- albumin level in blood decreases (normally maintains blood osmolarity because does not pass the filtration barrier) - here you get fluid retention by body tissues (edema)
diabetes insipidus
- net result = decreased ADH signaling + increased H2O loss in the urine –> see hyper glycemia
- classic thirst symptom of diabetes with no glucose metabolism problems
Ureter
= stellate lumen
- transitional epithelium
- loose lamina propria/submucosa
- 3 poorly defined layers in muscularis
- is small
urinary bladder
- mucoase is in many fold (if bladder empty/relaxed)
- transitional epitehlium
- thick wall of interlacing bundles of smooth muscle fibers
- bladder is big - compared to other organs it might be confused with
Orafice of ureter
- ureter crosses wall at oblique angle
- FXN: so the full bladder/pressure doesn’t back up to kidney and no back flow when contraction muscle for excretion
Urothelium (transitional epithelium)
= all of epithelium up until distal urethra that is in contact with fully modified urine
- urothelial cells have sensory function (mechansensation, chemosensation, can trigger activity in subjacent nerves by releasing NO + ATP)
- 3 layers of epithelium
1) umbrella cell layer - tight junctions between cells “plaques” forming asymmetrical unit membrane on out surface (uroplakin protein) - common site for UTIs (1st line of defense against them
- has modified cell membrane with uroplakin protein
- intracellular vesiclase fuse with surface membrane to expand apical surface of cell
2) Intermediate layer
3) basal layer - attached to BM
- stem cells
Urethra
- 20 cmin males (4cm prostatic, 1cm membranous, 15cm - penile) - shares function with reproductive system
- 3-5cm in females
- transitional epithelium thins to a Stratified or pseudostratified epithelium –> terminating distilling in SSNK –> SSK epithelium
