Histology Flashcards
what is histology?
- study of tissues
- 4 major tissues: epithelial, CT, muscular, nervous
epithelial tissue
- lines all body surfaces + cavities
- avascular (lacks blood vessels)
- tight junctions
functions: protection (stratified squamous), secretion (glandular), control of permeability (simple)
epithelial tissue: cell layers
simple: single layer, sits on basement membrane
stratified: several layer, bottom most sits on basement
pseudostratified: stretched single layer, sit on basement membrane
epithelial tissue: cell shape
cuboidal: specialized for secretion + absorption
columnar: secretion + absorption
squamous: irregular shaped (found on outer skin)
transitional: stratified cell but varies with stretch
glandular epithelium
- subtype of epithelial tissue
- adapted for secretion
- consists of exocrine + endocrine glands
glandular epithelium: exocrine glands
- secrete products on/in cavity
single celled: secrete mucous in digestive, urinary, reproductive + respiratory tract
multi-cellular: have ducts + passage ways (sudoriferous, sebaceous, salivary)
glandular epithelium: endocrine glands
- ductless
- secrete hormones into blood
connective tissue
- cells are separated by a matrix
blasts: form + secrete matrix
cytes: maintain matrix
clasts: breakdown matrix
connective tissue characteristics
- highly vascular
- lots of extracellular matrix
- function: support and connect tissues
matrix
- extracellular (surrounds cells)
1) protein fibers: collagen (strength), elastin (stretch + recoil)
2) ground substances: unstructured material located b/w cells
3) water
types of connective tissue
connective tissue proper: loose (areolar, adipose), dense (regular, irregular)
adipose CT: - adipocytes (large + store triglyceride)
- highly vascular (metabolism)
- little matrix
- functions: shock absorption, insulate, store energy
dense regular
- cells=fibroblasts
- little ground substance
- collagen fibers run in same direction
- forms tendons
dense irregular
- cells=fibroblasts
- little matrix
- collagen fibers run in diff. directions
- allows for stretch
bone
- spongy/compact
- cells=osteocytes (in lacunae)
- matrix (dense collagen fibers, hydroxyapatite crystals)
- highly vascular
cartilage
- cells=chondrocytes (in lacunae)
- firm matrix (tight collagen fibers)
- avascular
- ground substance=chondroitin sulfate + hyaluronic acid
blood
- RBC and WBC
- matrix is plasma
histology major junctions
3 membrane junctions:
1) tight tissue: prevent substances b/w cells (molecules fused together)
2) desmosomes: loose, use linker attachments (allows flexibility)
3) gap: connected adjacent cells, allows communication (smooth + cardiac muscles)
muscle types
skeletal: striated, voluntary movement
cardiac: striated, involuntary
smooth: non-striated, stretched area, involuntary
nervous tissue
neurons: conduct electrical impulses
glial cells: surround + protect neurons
membranes
- 2 or more tissues (simple organs)
- continuous multi-cellular sheets
membrane types
1) mucous: mucosa
2) serous: serosa
3) cutaneous: skin
mucous membranes
- line cavities leading out of the body
- epithelial layer (squamous/pseudostratified)
- areolar
- lamina proper
serous membrane
- lines cavities that do not lead out
- covers organs in cavities
- visceral layer (organs), parietal layer (wall)
pleura: lungs [v: lung surface / p: thoracic wall]
pericardium: heart [v: heart surface / p: mediastinum]
peritoneum: abdominal cavity + viscera
