Hist Exam 3

Functions of the skin

protection

vitamin D

lipid storage

thermoregulation

sensation

skin is a barrier to

UV, abrasion, chemical insult, dehydration

what cells synthesize vitamin D?

Keratinocytes

adipose tissue stores… from…

lipids from cholesterol conversion

layers of integument

epidermis, dermis, hypodermis

epidermis key points

avascular

stratum… corneum, granulosum, spinosum, basale

melanocytes

Langerhans

Merkel cells

IHC vs ICC? what cells require it to ID?

IHC- immunohistochemistry- antibody staining on tissue section

ICC- immunocytochemistry- antibody staining on cells

melanocytes, Langerhans, Merkel

what is the outermost layer of the epithelium? cell name? purpose?

stratum corneum, squame, water impermeant barrier

stratum basale includes…

keratinocyte stem cells

hemidesmosomes between keratinocytes and basal lamina

stratum spinosum includes

keratinocytes

desmosomes between keratinocytes (look like spines) attach via keratin filaments

what is a disorder of the hemidesmosomes? how does it happen? signs?

bullous phemphigoid, autoimmune condition against them

blisters in older perople

what is a disorder of the desmosomes? how does it happen? signs?

pemphigus vulgaris, antibodies to desmogleins in desmosomes

skin sloughing in infants

proteins of the desmosomes which can lead to pemphigus vulgaris

desmogleins and desmocolin

stratum granulosum key points

very basophillic granules (Odland bodies and keratohyalin granules)

what are inside stratum granulosum granules? what do they do?

Odland bodies- lipids and lipases/enzymes

keratohyalin granules- protein

together they combine with keratin to help make the squames

what is the finger of dermis coming up into the epidermis called? what is the part of the epidermis that goes into the dermis?

papillary dermis or dermal papilla

epidermal ridge (friction ridges)

dermal papilla made up of… what is the rest of the dermis called? made out of?

type III coll

reticular, dense irregular Type I coll

what degree burn to remove fingerprints?

3rd

skin regeneration

epidermis- 28-45 days

dermis- very slow regeneration

hypodermis- no regenerative ability

hypodermis key points

adipose tissue (triglyceride storage)

contribute to hormonal secretion

scientific terms for thick skin? thin skin?

acral skin

non-acral skin

acral vs non-acral skin

acral skin- no hair, prominent stratum corneum, stratum lucidum right under corneum

non-acral skin- hair, sebaceous gland, and erector papillae, whispy stratum corneum

psoriasis histology

skin cells divide when they should be differentiating

parakeratosis- stratum corneum retain nucleus

melanin originates from…

tyrosine

melanocyte key points

projections going up

sends out granules of melanin

keratinocytes detect UV, upregulate P53 (“DNA damage!”) becomes a transcription factor, causes keratinocyte to make melanocyte stimulating hormone

melanocyte will in response create melanin

langerhans cell key points

tissue resident macrophage that present antigens to T cells. An immune sentinel

merkel cell key point

mechanosensory cell- perception of fine touch like Braille

many found in the epidermal ridge

what are the appendages of the skin

hair follicles

fingernail

merocrine/eccrine sweat glands

fingernail composition

keratinized tissue with strong cross-linking

parts of the nail invagination

germinal matrix is the stem cell matrix outside the base of nail, becomes the nail bed toward the tip of finger

the root of the nail is the white part deep in the skin and becomes the nail plate outside the skin

the tissue on top of the root is the nail fold, becomes the eponychium (cuticle) on the nail plate

hair growth

invagination of epidermis into the dermis terminates with the hair bulb around a dermal papilla. stem cells where skin cells lose nucleus (dead squames) and elaborate the hair shaft

eccrine/merocrine secretion vs holocrine

eccrine/merocrine- secretion of protein (like sweat)

holocrine- the whole cell comes off (sebaceous gland)

sweat gland key points

secretes hypotonic fluid, made up of a duct (basophillic double cuboidal) and secretory coiled base (light staining) located in dermis

duct absorbs Cl- in the salty water to make it hypotonic

under EM- secretory shows dark cells (makes protein) and light cells (makes ultra filtrate), and gray myoepithelial cells on the periphery (expels sweat)

how do the ducts reabsorb Cl-? what happens if it doesn’t work?

cystic fibrosis transmembrane conductance regulator (CFTR) a transmembrane chloride channel shunts Cl- into interstitial space

salty sweat in cystic fibrosis

what is the mechanism that controls blood flow to outer skin in response to hot or cold? between what plexuses?

anteriovenous anastamoses, papillary plexus, cutaneous plexus

sensory organs of the skin

fine touch- meissner’s corpuscles, Merkel cells, free nerve endings

deep pressure- pacinian corpuscle

meissner’s corpuscles

Senses light touch

Has a thin capsule (can’t see) and lives in the dermal papilla.

made up of elongated schwann cells, a connective tissue capsule, and a central axon. Can see better with an axon stain

free nerve endings key points

goes to epidermis

senses pain, hot and cold, light touch but slow to respond

pacinian corpuscle key points

Senses pressure in between dermis and hypodermis or deep in hypodermis

important for proprioception

circular lamellae like an onion

what cells are affected in squamous cell carcinoma

keratinocytes of epidermis

what cells are affected by melanoma

melanocytes, but can be anywhere neural crest cells migrate (GI or brain)

skin pigment disorders covered in class

albinism- no melanin tyrosinase

vitiligo- autoimmune loss of melanocytes

melasma- too active melanocytes (mask of pregnancy)

The main components of the GI tract are

GI tract tube

accessory organs

GI tract main functions

transit of foodstuffs via peristalsis

enzyme secretion

digestion, absorption

excretion of wastes

Layers of the GI

mucosa

submucosa

muscularis propria

adventitia

what is included in the mucosa?

epithelium, lamina propria, muscularis mucosa

what is included in submucosa?

loose connective tissue layer (coll and elastic)

large blood vessels, lymphatics, nerves

glands

what is included in the muscularis propria?

inner circular muscle layer

outer longitudinal muscle layer

what is included in adventitia?

loose connective tissue

Esophagus key points

mucosa- stratified squamous non-keratinized, lymph nodules in lamina propria (no goblet cells)

submucosa- submucosal glands

muscularis externa- skeletal in upper, smooth in lower, auerbach’s plexus

adventitia- dense and thick, within mesentery with mesothelium

the transition of esophagus to stomach is called

gastro-esophageal junction

stomach function

turns food to chyme via

mechanical grinding, chemical (HCl) and enzymatic degradation

stomach enzymes include

pepsinogen (activated by acid)

gastric lipase

chymosin (milk enzyme for babies)

regions of stomach functions

cardia- mucin secreting

fundus- mix of glands

pyloric region- mucin secreting and endocrine

folds of the stomach is called…

rugae

stomach key points

mucosa- gastric pits are simple columnar epithelium which invaginates into lamina propria. Gastric glands go deeper, looks more bubbly

submucosa- Meissner’s plexus (not corpuscles)

muscularis externa- oblique, circular, and longitudinal layers of smooth muscle. myenteric plexus in between layers

gastro-esophageal junction key points-

stratified squamous to simple columnar

set of lymph nodules

emergence of surface mucous cell and gastric pits

looks like the smooth muscle gets thinner

dysfunction of gastro-esophageal junction

Barrett’s esophagus from acid reflux

stratified squamous epithelium of esophagus becomes simple columnar with goblet cells

can’t swallow, heartburn, and blood in vomit or stool

function of meissner’s plexus and myenteric plexus?

peristalsis

another name for myenteric plexus?

Auerbach’s plexus

cardiac stomach key points

mucosa- pits ½ depth of mucosa

coiled glands

mucous secreting glands only

fundus key points

pits ¼ of mucosa

straight glands

mucous secreting cells, parietal, chief cells, endocrine cells

Gastric mucosa cells and what they produce

surface mucous cell- makes alkaline mucins and bicarb, looks goblet-like

mucous neck cell (in gastric pit), looks round with mucous bubbles

parietal cell- makes HCl, intrinsic factor, and TGF-alpha light fried egg

chief cell- makes pepsinogen and lipase, at the base of glands, basophilic

enteroendocrine cell- paracrine and endocrine hormones, small round guys that stains differently depending on the hormone

what kind of secretory cell are the gastric mucous cells?

regulated secretory

what does intrinsic factor do? secreted by what?

vitamin B12 absorption

Parietal cell

vit B12 deficiency disease

atrophic gastritis (after 60, fewer parietal cells)

gastric bypass surgery or chemotherapy- reduces cells

vegan diet

small intestine disease

pernicious anemia- auto-immunity against intrinsic factor

what does TGF-alpha do? secreted by…

regulates stomach acid and cell prolif/migration

parietal cell

treatments for GERD

Antacids

Histamine receptor antagonist

H/K ATPase inhibitor

Why are chief cells basophilic?

big rough ER

What does pepsinogen do?

gets converted into pepsin by acid

pepsin breaks up denatured proteins

pyloric region contains nearly no…

parietal and chief cells

Small intestine key points

plicae circulares (submucosa core), villi (lamina propria core, muscularis mucosae base) microvilli- brush border, looks like a pink line

crypts of Leiberkuhn

lamina propria- core of villus, lacteals, capillary plexus

submucosa- vessels, meissner’s plexus, brunner’s glands (duodenum) Peyer’s patch (ileum)

cells in the crypts of Leiberkuhn

stem cells

paneth cells- innate immune cells that target pathogens, look like raspberries

enteroendocrine cells (D and G cells)- release hormones

enterocytes- tall columnar epithelial cell that digest and absorb nutrients (also on the villi)

goblet cells

how do paneth cell operate?

make anti-microbial peptides, alpha-defensins that poke holes in bacteria

what immune cells are found in the lamina propria?

lymphocytes mostly

lacteals are destinations of…

chylomicrons

Brunner’s glands location, function, and how to identify

submucosa of duodenum, secretes alkaline mucin which protects from stomach acid

looks like a bunch of bubbles in the submucosa, under villi

Peyer’s patches are found where? what is the important cell?

submucosa of small intestine

M (microfold) cells

Gastro-duodenal junction key points

Mucosa- epithelium stays simple columnar but goes from surface mucous cells to enterocytes and goblet cells

goes from gastric pits/glands to villi and crypts

lymphatic nodules in pylorus but not in duodenum

Submucosa- Brunner’s glands appear in duodenum

colon main functions

absorbs water

forms and excretes feces

colon key points

mucosa- epithelium invaginates all the way to muscularis mucosa, straight tubular glands (like crypts)

mucosal glands

no villi

more goblet cells, but still mostly absorptive cells

lymphoid nodules in the lamina propria

inner circular muscularis externa is complete, but outer longitudinal layer is in 3 bundles (taenia coli)

crypts of large intestine contains

stem cells

mucosal glands of the large intestine functions

protection

lubrication

immunity- traps pathogens, antimicrobial

wound healing support

What immune cells are in layers of the large intestine? what layer?

macrophages, plasma cells, eosinophils, lymph nodules

lamina propria

recto-anal junction clinical significance

preferred site for HPV (17 fold higher rate of cervical HPV-caused cancers compared to anal cancers)

liver receives blood from… drains to…

hepatic artery and hepatic portal vein

IVC

hepatocyte function

Chemical factory- clears portal blood of nutrients

secretes proteins like albumin, transferrin, etc

makes enzymes, cholesterols, LDLs, vit A

makes and recycles bile salts (lipid digestion) and IgA

Blood filter- traps, breaks down and eliminates pathogens and toxins

filters out old blood and HDL/cholesterol

Warehouse- stores glycogen, some cholesterol, and vit B12, E, K, D and ferritin

sends cholesterol to adipose cells

hepatocyte shape and takes up how much of the liver?

cuboidal epithelial cell 70-85%