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1

KIDNEY

  • pale cortex / dark medulla / 10-15 meduallary pyramids
  • cortex contains glomeruli and coils of proximal/distal tubules
  • medulla contains pyramids with straight parts proximaal/distal tubule, loop of Henle, collecting duct

Blood

  1. 5/6 branches renal artery
  2. arcuate arteries at medullary/cortical border (give off vasa recta - deep to medulla)
  3. then interlobular arteries penetrate cortex at regular intervals
  4. affertent to glomerulus
  5. efferent from glomerulus (filtered blood) - thin walled and between tubules
  6. acquire fluid and ions -> drain to arcuate veins -> systemic

2

GLOMERULUS

  • blood to glomerulus for filtration
  • passes primary filtrate to nephron for selected reabsorption
  • parallel array of fenestrated capillaries ensheathed by podocytes
  • between loops = mesangiel cells (matrix forming)
  • afferent arteriole wall produces renin
  • next to glomerulus = segment of distal tubule with macula densa

3

GLOMERULAR TUFT (PAS)

  • arise from vascular pole of glomerulus = entrance afferent and exit efferent
  • in this angle lies a distal loop of nephron with palisade of macula densa
  • capillary loop surrounded by podocyte
  • surrounded by urinary space - separates glomerulus from bowman's capsule
  • arrow to distal tubule
  • MACULA DENSA - around blood vessels regulate blood flow, provides framework for glomerulus. 

4

FILTRATION BARRIER

  • basement membrane
  • synthesised and maintaiend by endothelial capillary cells and epithelial cells (podocytes) that ensheath them
  • endothelial = fenestrated
  • podocytes stand off membrane with foot processes
  • creates physical pores
  • pores guarded by filtration membrane
  • membrane is charged and resists passage of some molecules
  • water and solutes may pass to urinary space = primary filtrate

5

PROXIMAL TUBULES (PAS)

  • highly coiled (sometimes with straight projection to medulla)
  • prominent brush border and complex invaginations @ basolateral membrane dark pink
  • extensive reabsorption here
  • Na+ active transport with glucose (cotransporter - GLUT)
  • take up protein and polypeptide by endocytosis
  • cells contain lyzosomes which break down proteins before returning to circulation
  • any small negatively charged protein can enter primary filtrate

6

PROXIMAL TUBULES 2 (PAS)

  • this slide - straight portion of proximal tubule
  • leads to loop of Henle
  • if glomeruli present = cortex
  • some project to medulla

7

LOOP OF HENLE (PAS)

  • mostly @ medulla
  • thick/straight descending, thin loop, thick ascending 
  • thick descend = similar to proximal tubule
  • thick ascend = similar to distal tubule
  • longest thin loop penetrate deepest to medulla when glomerulus = cortico-medulla junction
  • thin descending portion = low permeability to ions and urea, high permeability to water
  • thin ascending portion retains water, reabsorption Na+ and Cl- 
  • this produces dilute/hypotonic filtrate but a hypertonic interstitium
  • vasa recta (straight capillaries) run alongside tubules

this slide - thick and thin limbs and vasa recta

8

DISTAL TUBULE (PAS)

  • from medulla to cortex then to vascular pole of glomerulus
  • macula densa here monitors sodium levels to influence intitial filtration of glomerulus
  • paler than proximal
  • deep invaginations of basal plasma membrane with numerous mitochondria
  • mitochondria indicative of control acid/base balance and concentration of urine (ATP)
  • with aldosterone sodium reabsorbed, potassium excreted
  • bicarbonate ions reabsorbed, hydrogen excreted - acidic urine

@ cortex both proximal and distal tubules present

proximal more tightly coiled therefore appear to be more numerous

9

COLLECTING DUCTS (PAS)

  • pale cuboidal cells
  • wide lumen
  • starts at cortex, filtrate to collecting tubules than larger ducts
  • collecting tubules from many nephrons coalesce to larger ducts and form visible streaks - medullary rays
  • few organelles
  • collecting tubules - dark intercalated cells with high mitochondria
  • surrounded by hypertonic medium interstitial from loop of Henle
  • ADH increases permeability to water (concentrates urine)

prone to kidney stones and infection

10

JUXTAGLOMERULAR APPARATUS (PAS)

  • afferent/efferent arterioles, macula densa, lacis cells
  • afferent - cells produce renin - granules in cytoplasm
  • renin catalyses angiotensin 1 (liver) -> angiotensin 2 (conversion at lungs) -> aldosterone release by suprarenal cortex -> reabsorption of sodium and water @ distal tubules and collecting ducts
  • lacis cells and macula densa regulate renin secretion by monitoring sodium levels

this slide - obvious macula densa

11

UROTHELIUM

  • ureters, bladder and most urethra
  • pseudo-stratified epithelium
  • surface cells adapted to withstand prolonged urine exposure
  • 3-8 layers (distension dependent)
  • basal cells = cuboidal
  • above = columnar (relaxed)
  • surface = large, binucleate umbrella cells

umbrella cells:

  1. thickened membrane plates joined by thin membrane bands
  2. lipid composition (unique)
  3. relaxed plated = perpendicular to membrane
  4. stretched = drawn to surface of cell

12

URETER

  • epithelial tube with 2 helical layers of smooth muscle
  • star shaped lumen
  • towards bladder = longitudinal smooth muscle
  • 3 constrictions (kidney stones will lodge here)
    1. origin (pelvis of kidney)
    2. at sacro-iliac joint (passes to true pelvis)
    3. as enters postero-inferior bladder surface
  • reflux prevented by compression of ureter by muscular wall bladder
  • contains blood vessels and adipose
  • smooth muscle for peristaltic contraction

13

URINARY BLADDER 

  • wall = thick bundles of smooth muscle with no preferred direction except neck = 3 distinct layers
  1. innermost = longitudinal projects inferiorly and turns transversely to form a sphincter around prostatic urethre (male) and external meatus (female)

thrown into folds w/ umbrella cells

walls of bladder contains small nerves (autonomic)

sympathetic NS = mainly blood vessels at bladder

inset = nerves

micturition

when external sphincter relaxes (sympathetic) and muscle wall (detrusor) contracts (para)

14

PROSTATIC URETHRA

  • urethra longer in males
  1. prostatic
  2. membranous
  3. bulbous
  4. pendulous
  • urothelium (pseudo-stratified columnar) except at distal end
  • mucus glands along length
  • distal urethra = stratified squamous (male and female)
  • both sexes = striated (voluntary) muscle sphincter from muscles of pelvic diaphragm around membranous part
  • under prostatic urothelium = dense fibrous connective tissue to prevent distension

inset = U-shaped prostatic urethra

15

TESTES

  • within collagenous capsule = tunica albuginea
  • within fibrous septa to 250 lobules (each lobule with up to 4 germ cell producing semniferous (tubules)
  • semniferous tubule = 50cm loop (open both ends)
  • drain to rete testes (channels)
  • Leydig cells between semniferous tubules

16

SEMNIFEROUS TUBULE

  • stratified epithelium with support (sertoli) and germ line (developing spermatazoa)
  • at periphery = germinal epithelial 
  • GE produces large cells with speckled chromatin = spermatagonis
  • spermatogonia develop to spermatocytes
  • spermatocytes pass blood testis barrier created by Sertoli
  • Sertoli = blood testis barrier and nurture sperm
  • production = 64 days 
  • maturation wave passes slowly down each tubule

17

SEMNIFEROUS TUBULES

  • thin fibrous capsule
  • closest to membrane = germinal epithelium with spermatogonia (speckled)
  • between cells are smaller primary spermatocytes and Sertoli cells (pale irregular nuclei)
  • towards centre depends on stage in cycle
  • sometimes primary/secondary spermatocytes (small dense nuclei)
  • otherms more mature (narrow and elongated heads)
  • between tubules = leydig clumps

arrow to spermatid

reduction division (2n-1n -> first meiotic) takes place when primary to secondary @ luminal side of blood testis barrier i.e. not in contact with blood stream

18

EPIDIDYMIS

  • rete testis = cuboidal ep
  • rete testis to efferent ductules (similar)
  • epididymis = single 5m coiled tube
  • thick fibrous capsule attached to mediastinum of testes posteriorly - storage and maturation site for sperm aggregated within lumen
  • tall pseudo-stratified columnar ep
  • small rounded basal cells support tall columnar with microvilli (stereocilia) 
  • stereocilia (non-motile) reabsorb seminal fluid, phagocytose damaged sperm and cell debris. also nutrients for sperm
  • thin layer of smooth muscle thicker as approaches vas

19

VAS DEFERENS

  • spirally arranged smooth muscle
  • similar to epididymis but shorter cells and microvilli
  • sometimes has longitudinal folds - lamina propria
  • sudden and rhythmical contraction expels sperm

thick muscular wall makes vas feel cord like

20

SEMINAL VESICLE

  • highly coiled glands at postero inferior bladder
  • double layered capsule of smooth muscle
  • long narrow folds
  • stimulated by testosterone - enlarge and secrete creamy opalescent fluid with acid pH. rich in globulin, vitamin C, amino acids and sugars
  • contraction of smoooth muscle mixes with spermatozoa
  • simple columnar epithelium

21

PROSTATE

  • 50 branched tubular glands
  • smooth muscle matrix
  • smooth muscle capsule around all
  • 3 layers (concentric) of glands - mucosal - submucosal - main
  • @ ejaculation, contract and mix secretions @ ejaculatory duct

22

PROSTATIC EPITHELIUM

  • glands varied - straight, coiled, branched
  • epithelium thrown into broad, branching folds
  • with testosterone, cells increase in height and secrete digestive enzymes - acid phosphatase (major component of seminal fluid) - (PSA) prostate specific antigen
  • lumen often with sec product / calcified glycoprotein

23

PROSTATE 2

  • this slide L - skeletal muscle at underside of prostate - pelvic diaphragm with levator ani
  • this slide R - spiral tubular gland at submucosal level

24

PENILE URETHRA

  • prostatic, membranous, penile
  • membranous and penile = non-secreting pseudostratified columnar
  • at distal end = stratified squamous epithelium (within glans)
  • bulbo-urethral glands within membranous urethra produce watery galactose rich secretion, precedes main ejaculate - can sometimes be a problem with catheterisation

25

PENIS

  • erectile compartments = large endothelium lined blood vessels supported by connective tissue
  • each surrounded by compact collagen layer tunica albuginea
  • helicine branches of pudendal artery
  • when flaccid arteries transmit very little blood due to artero-venous shunts
  • para. stimulus shut shunts (point and shoot)
  • most skin = hairy, loosely attached to columns - except prepuce and glans (non-kerat)

26

VAGINA

  • stratified squamous thinly keratinised at vulval end
  • thin pre-puberty and post menopause
  • beneath epithelium = lamina propria with small blood vessels (moisture by diffusion)
  • surrounding epithelium = fibro muschular tube with collagen/elastic and smooth muscle
  • sphincter of skeletal muscle at lower end
  • bartholin glands - mucus posterolaterally at lower end of vagina
  • with age = weaker fibro-muscular tube

27

EPITHELIAL SQUAMES

  • in menstrual cycle surface cells accumulate glycogen and flake off
  • desquamated cells rupture and bacteria generate lactic acid
  • low pH at vagina

pale green cells - outermost layer, predominate at first half of menstrual cycle

pink cells - deeper layer

28

CERVIS

  • protrudes to anterior wall vagina
  • surrounded by gulley - lateral, anterior, posterior ornices
  • outer surface - SSNKE (identical to vagina)
  • cervical canal (between internal and external os) = tall columnar epithelium thrown into deep gland-like folds
  • stroma = fibrous connective and smooth muscle
  • this slide - external os

29

CERVICAL LINING

  • secretes mucus - consitency of which varies throughout menstrual cycle
  • first half - thin and watery
  • second half - viscous after ovulation as plug to prevent microorganism entry
  • transitional zone - between sensitive cervical lining and other stratified squamous epithelium prone to infection and lesion
  • this slide - mucus glands visible

30

UTERINE BODY

  • 3 poorly defined layers myometrium smooth muscle
  • lined by epithelial endometrium
  • myometrium hormonally sensitive

hyperplasia and hypertrophy @ pregnancy

large arteries and veins between inner and middle layers, also supply endometrium and give rise to spiral arteries (significant @ menstruation)