e1 LO's

parenchyma

the functional tissue of an organ

stroma

CT framework supporting the parenchyma

serosa

thin simple squamous layer lining outer organ surfaces in body cavities

mucosa

specialized epithelium + CT lining luminal surfaces of tubes/cavities with an external connection

apical

luminal/free surface

basal

adjacent to BM

lateral

side attaching to neighboring cells

4 basic tissues

epithelium, connective tissue, muscle, nervous

epithelium examples

epidermis, gut lining, glands

connective tissue examples

CT proper, cartilage, bone, blood

3 types of muscles

skeletal, smooth, cardiac

nervous tissue examples

brain, spinal cord, peripheral nerves

simple epithelium

all cells touch the BM

stratified epithelium

only the basal row attaches to the BM

mesothelium

simple squamous, lines body cavities and the outer surface of organs w/in them and is serous

endothelium

simple squamous, lines all blood and lymphatic vessels and the internal surface of the heart

Why are pseudostratified columnar & transitional epithelium "simple" despite looking stratified?

b/c all cells touch the BM

simple squamous epithelium

Single layer, flat cells; e.g., mesothelium, endothelium

simple cuboidal epithelium

Single layer, cube-shaped cells; ducts; secretion/absorption

simple columnar epithelium

Single layer, tall cells; glands; secretion/absorption

Pseudostratified columnar epithelium

Simple but looks stratified; ciliated or non-ciliated; respiratory tract

Transitional epithelium

Simple; cells slide/stretch; urogenital tract

Stratified squamous epithelium

Multiple layers; basal cells cuboidal/columnar flattening toward surface; keratinized/non-keratinized/mixed

Stratified cuboidal epithelium

2 layers of cuboidal cells; glands/ducts

Stratified columnar epithelium

2 layers; basal cuboidal, apical columnar; glands/ducts

hemidesmosomes

integrins, attaches all cells to BM in simple, but only basal layer in stratified

desmosomes

cadherins, attaches neighboring cells laterally in both simple & stratified

microvilli

non-motile, short, ↑SA

stereocilia

non-motile, very long microvilli

cilia

motile, 9+2 arrangement, move fluid unidirectionally

flagella

motile, 1/cell, longer, 9+2, propel sperm

Two kinds of dense regular CT

Collagenous (tendons/ligaments); Elastic (elastic ligaments)

examples of collagenous dense regular CT

tendons and ligaments

examples of elastic dense regular CT

elastic ligaments

Two types of adipose tissue

White (unilocular); Brown (multilocular)

Loose irregular (areolar) CT

Irregular orientation, thin/small collagen bundles, fibroblasts, ground substance relatively abundant

Dense irregular CT

Irregular orientation, thicker/larger collagen bundles than loose CT, less ground substance, fibroblasts

Dense regular CT

Collagen bundles oriented in the same direction, fibroblasts; tendons/ligaments

Reticular CT

Mesh-like network of reticular fibers/cells; framework of bone marrow, lymph nodes, spleen, liver, endocrine glands

Adipose tissue

Dominated by adipocytes with a delicate collagen/reticular network; white or brown

"Hydrated gel" polymer in cartilage ECM

ground substance, GAGs/proteoglycans (aggrecan) bound together by hyaluronic acid

Two cell types of cartilage

chondroblasts and chondrocytes

chondroblasts

actively dividing and secreting in matrix

chondrocytes

mature, maintain matrix

Fiber visible in fibrocartilage

Type I collagen, herringbone (zigzag) pattern

Fiber visible in elastic cartilage

Elastic fibers (plus type II collagen)

Fiber invisible in hyaline cartilage

Type II collagen — blends into the matrix

Hyaline cartilage

Type II collagen; chondrocytes in lacunae/isogenous groups; perichondrium (except articular surfaces); fetal/young bone-forming sites, larynx/nose, airways

Elastic cartilage

Like hyaline + visible elastic fibers; frequent isogenous groups; external ear, auditory canal/tube, laryngeal/epiglottic cartilage

Fibrocartilage

Type I collagen; small chondrocytes in lacunae between dense bundles; no perichondrium; discs, tendon/ligament-to-bone, menisci

Interstitial cartilage growth

from within (lacunae form isogenous groups, expand inside)

appositional cartilage growth

on the surface (perichondrial stem cells secrete matrix onto surface)

osteoblasts

Cover inner/outer bone surfaces, secrete osteoid; inactive = bone-lining cells; NOT in lacunae

Osteocytes

Derived from osteoblasts; in lacunae; communicate via canaliculi

Osteoclasts

Multinucleated giant cells; resorb bone (enzymes + acids); create erosion lacunae

ECM of bone, its collagen, and its mineral

Osteoid; type I collagen; hydroxyapatite crystals mineralize it

Woven bone

Immature; no Haversian systems; rapid, irregular formation; fetal bone/fracture repair; later replaced by lamellar bone

Lamellar bone

Mature; has Haversian systems; slow remodeling of woven bone; organized lamellae; most of adult skeleton

parts of the haversian system

central canal, lamellae, osteocytes in lacunae, canaliculi, perforating canals, interstitial lamellae, inner circum lamellae, outer circum lamellae

central canal

center of osteon, contains blood/lymph vessels & nerves

lamellae

Concentric layers of bone matrix; alternating collagen direction

osteocytes in lacunae

Reside at regular intervals between lamellae

canaliculi

Connect adjacent lacunae; cell communication, nutrient/waste flow

perforating canals

Interconnect central canals & the medullary cavity

interstitial lamellae

Orphan fragments of degraded osteons; no central canal

inner circumferential lamellae

Circle marrow cavity, smooth inner surface, covered by endosteum; not part of osteons

outer circumferential lamellae

Smooth outer surface, covered by periosteum; not part of osteons

CT proper of endosteum

Loose collagenous CT; lines all inner bone surfaces & surrounds blood vessels within bone

CT proper of periosteum

dense CT overall

2 layers of periosteum

fibrous and cellular

fibrous layer

outer, dense regular to irregular CT, acts as a capsule, fibroblasts are primary cells

cellular layer

inner, between the fibrous layer & cortical bone, highly cellular & filled w/osteoprogenitor cells

Fibrous structures anchoring periosteum to bone

Perforating (Sharpey's) fibers — type I collagen; also anchor tendons, ligaments, periodontal ligament

myocyte

Individual muscle cell (myofiber)

What creates the "stippled" pattern (transverse)?

Myofibrils cut in cross-section

What creates light/dark banding (longitudinal)?

Alternating thick (myosin)/thin (actin) filaments forming A bands (dark)/I bands (light) in sarcomeres

cardiac muscle has

Branching pattern + gap junctions in intercalated discs

smooth muscle has

a Fusiform shape, small diameter (transverse)

skeletal muscle has a

Endomysium surrounds each cell

Multiple peripheral nuclei?

skeletal muscle

Central nucleus with glycogen halo?

cardiac muscle

Central nucleus filling small cell diameter?

smooth msucle

endomysium encloses

one cell

perimysium encloses

groups of cells (fascicles)

epimysium encloses

the entire muscle

key features of skeletal muscle

Voluntary, striated, multinucleated/peripheral nuclei; syncytium; endomysium/perimysium/epimysium

key features of cardiac muscle

Involuntary, striated (less prominent); branching, intercalated discs; usually 1 central nucleus; only in heart

key features of smooth muscle

Involuntary, non-striated (crisscrossed filaments); fusiform cells; 1 central nucleus filling cell width

Components of the CNS

Brain and spinal cord

Components of the PNS

Cranial nerves, spinal nerves, sensory ganglia

Components of the ANS

Motor ganglia/nerves to organs (glands, cardiac & smooth muscle); sympathetic + parasympathetic

Components of the SNS

Motor nerves to skeletal muscle

Unipolar neuron

Single axon bifurcating into central & peripheral branches; sensory ganglia, dorsal root ganglia

Bipolar neuron

One axon + one dendrite; retina, olfactory epithelium, vestibulocochlear ganglia

Multipolar neuron

Many dendrites + one axon; motor neurons, interneurons, autonomic ganglion neurons

Sensory neuron

Afferent; to CNS; e.g., dorsal root ganglion neurons

Motor neuron

Efferent; away from CNS; e.g., ventral horn motor neurons

Interneuron

Between neurons; e.g., dorsal horn, sensory→motor

Cell body, nucleus, nucleolus of a neuron

Cell body = Nissl-rich cytoplasm. Nucleus = large, central, euchromatic. Nucleolus = large, within nucleus

Axon hillock vs. cytoplasm — staining?

Axon hillock lacks Nissl (not basophilic); cytoplasm is basophilic (Nissl-rich)