Extra Histology

overall functions of urinary system

overall functions of urinary system

filter blood to remove wastes and toxins. Produce, transport, store, and eliminate urine

endocrine functions

regulate blood pressure (renin) and RBC concentration

hilium/pelvis

internal space for urine to collect. attached to ureter for urine to be drained and carried to bladder

nephrons

basic functional unit of the kidney each Nephron independently filters blood to produce urine

renal corpuscle

initial contact between nephron and blood. blood filtration water and small molecules leave plasma and enter nephron

proximal convoluted tubule

reabsorption of water electrolytes and nutrients secretion of organic ions

loop of henle

continued reabsorption of water and electrolytes

distal convoluted tubule

reabsorption of electrolytes

connecting tubule and collecting duct

collect final filtrate and carry to calyces/pelvis/ureter

for efficient exchange between nephron fluid and blood

nephrons lined with simple epithelium

glomerulus

tissues of the nephron surround a cluster of capillaries

filtrate

water and small molecules exit blood and enter nephron creating fluid

structures in the renal corpuscle

glomerulus, glomerular capsule

glomerular capsule

beginning of the nephron surrounds the glomerulus

visceral layer of glomerular capsule

cells that directly overlay capillaries

parietal layer of glomerular capsule

outer lining of the corpuscle

capsular space of the glomerular capsule

space where filtrate collects as it exists blood before proceeding through the rest of the nephron

parietal layer made up of

simple squamous epithelium creating outer capsule of corpuscle

PCT

the next region go the nephron and drains filtrate from the capsular space in the renal corpuscle

glomerular filter

determines the components of the blood exit and enter the capsular space of the real corpuscle

3 components of the of the glomerular filter

the walls of the glomerular capillaries, a shared basement membrane, and the podocyte slit diaphragms

walls of glomerular filter capillaries

fenestrated, gaps in capillaries walls create sieve that allows material below a certain size to exit the blood stream

basement membrane of the glomerular filter

creates a size specific barrier also slightly negatively charged thereby repelling there negatively charged molecules

podocyte slit diaphragms

molecular mesh located in small gaps between podocyte extensions, also creates a size and change specific barrier

yellow-glomerrulus

capsular space

parietal layer

PCT

after exiting the renal corpuscle the filtrate passes through

the PCT, the loop of henle, and the DCT

functions of the PCT

reabsorption of water, electrolytes, and organic nutrients. secretion of organic ions including many drugs

structure of PCT

highly convoluted located in cortex, simple cuboidal (thin enough for absorption), microvilli to increase surface area, abundant mitochondria for active transport

thin descending and ascending limbs

simple squamous epithelium for passive transport of water and ions

thick ascending limb

simple cuboidal epithelium for active transport of ions acidophilic due to many mitochondria

DCT

ion reabsorption albeit at lower rate than elsewhere in the nephron. located in cortex and lined with simple cuboidal epithelium

How can DCT be distinguished from PCT in cortex

lower rate of absorption in DCT means fewer microvilli and fewer mitochondria (paler cytoplasm). shorter than PCT

collecting ducts

drain relatively finished urine from nephrons and carry it though medulla towards renal pelvis

collecting ducts are lined with

simple cuboidal epithelium with a cytoplasm that is slightly acidophilic

renin

produced by a structure called the juxtaglomerular apparatus located next tot he renal corpuscles

juxtaglomerular apparatus

specialized sensory structure located along DCT where it comes in close contact with renal corpuscle. regulates renal corpuscle function and carries out one endocrine function of the kidney-regulates blood pressure

umbrella cells

secrete protective glycoproteins and lipids, protect epithelium and underlying tissues from urine, domed apical surface is also capable of stretching to accommodate changes in urine volume

endocrine glands

products must be deposited into bloodstream and widely circulated.

two parts of the pituitary gland which is attached to the hypothalamus

anterior and posterior

anterior

glandular tissue derived developmentally from the pharynx

posterior

secretary nervous tissue derived from the forebrain

anterior pituitary function

produces TSH, PRL, FSH, LH, GH, ACTH

Three segments of anterior pituitary

pars distalis, pars tubercles, pars intermedia

pars distalis

largest region of anterior pituitary

pars tuberalis

small region next to interfundibular stalk

pars intermedia

small region between anterior and posterior pituitary with lingering cysts

basophils of anterior pituitary

purple stain

acidophils

products stain pink or orange

chromophobes

there are thought to act as stem cells and this have pale cytoplasm due to lack of secretory granules

posterior pituitary

contains the axons of secretory neurons, contains support cells celled pitiocytes,

product of posterior pituitary

oxycontin (love, trust) regulates the mammary glands and uterine contractions

ADH

acts on the kidneys to promote water resorption from urine

1. acidophil

2. basophil

3. chromophobe

pancreatic islets structure

highly vascularized clusters of pale staining cells amidst the much more extensive exocrine tissue of the pancreas

alpha cells

secrete glucagon to elevate blood glucose concentration

beta cells

secrete insulin to decrease blood glucose concentration

d cells

secrete somatosatin a hormone that regulates the Alpha and beta cells as well as cells in the pituitary and stomach

pp cells

secrete pancreatic polypeptide which regulates the pancreatic acinar cells as well as cells in the stomach

endocrine vs exocrine tissue

highly pale staining cells amidst the much more extensive exocrine tissue cells of the pancreas

adrenal glands products

aldosterone, glucocorticoids, DHEA, catecholamines

adrenal gland structure

external capsule, cortex has three distinct layers, internal medulla

outermost layer beneath capsule

zona glomerulosa which includes small pyramidal cells producing aldosterone

middle layer of adrenal cortex

zona fasciculata which includes large polyhedral cells with abundant lipid droplets produce glucocorticoids

internal layer of the adrenal cortex

zone of reticularis which is more intensely stained cells that produce DHEA

chromaffin cells

produce catecholamines

parts of the adrenal gland

Directly under the capsule- glomerulosa-aldosterone

Pale staining cells- fasciculata-glucocorticoids

Darker staining-reticularis- DHEA

Medulla-catelcolemines

zona glomerulosa

aldosterone

zona fasciculata

glucocorticoids

zona reticularis

DHEA

medulla

catecholamines