Anatomy and Physiology chapter 4 - histology

4 primary tissues

1. epithelium (covering)

2. connective tissue (support)

3. muscle (movement)

4. nervous (control)

histology

the study of tissue

basic functions of epithelial tissues

protection

absorption

filtration

excretion

secretion

sensory reception

special characteristics of of epithelium

1. cellularity - closely packed cells

2. specialized contacts - demosomes (anchors cells together); tight junctions (form impermeable layers); gap junctions (communication)

3. polarity - apical surface (faces free space); basal surface (closer to basal membrane)

4. supported by connective tissue - areolar connective tissue (reticular lamina lies below basal lamina and secreted by connective tissue)

5. avascular but innervated

6. regeneration

basement membrane

basal lamina + reticular lamina of connective tissue

resists tearing and stretching forces

defines epithelial boundary

simple squamous epithelium

structure: single layer of flat cells; nuclei often seen as bumps

function: diffusion, filtration

location: lungs, kidneys, and blood vessel walls, serous membranes

simple cuboidal epithelium

structure: single layer, cube shaped, some have microvilli

function: secretion and absorption

location: kidney tubules and glands

simple columnar epithelium

structure: single layer of tall, narrow cells

function: secretion and absorption, movement of particles

location: lines digestive tract

*microvilli and goblet cells

pseudostratified columnar epithelium

structure: 1 cell thick, looks stratified, nuclei at different levels (none at apical side), cilia

function: secretion and absorption, secrete mucus

location: respiratory tract

stratified squamous epithelium

structure: multiple layers, cube shaped in basal layer and progressively flattened towards apical layer

function: protection against wear and tear

location: skin, anus, nose, esophogus

stratified cuboidal epithelium

structure: multiple layers, cube shaped

function: secretion

location: sweat glands and mammary glands

stratified columnar epithelium

structure: multiple layers with tall, thin cells

function: protection, secretion

location: glands, male urethra, pharynx, and transitional areas

transitional epithelia

structure: multiple layers; cube shaped when not stretched and squamous when stretched

function: accommodate fluctuations in amount of fluid

location: lining of urinary organs

gland

consists of one or more cells that make and secrete a product (goblet cell = gland)

glandular epithelia

endocrine glands - ductless that secrete hormones into the blood (not lined with glandular epithelium)

exocrine glands 0 secretes products onto body surfaces or into body cavities (using a duct)

types of glandular epithelia

unicellular exocrine glands - goblet cells

multicellular exocrine glands - 2 parts; acini cells - secretory cells of gland, duct cells - form a duct for passage of product onto surface or body cavity

3 modes of secretion

merocrine glands - exocytosis (sweat glands, salivary glands)

holocrine glands - accumulate products until they rupture; constant mitosis

apocrine glands - excrete by pinching off apical portion of the cell (mammary glands)

4 main classes of connective tissue

connective tissue proper

cartilage

bone

blood

four main functions of connective tissue

binding and support - tendons

protection - immune system

insulation and cushioning (fat)

transportation - blood

storage (fat)

common characteristics of connective tissue

1. common origin (derived from mesenchyme)

2. varying degrees of vascularity

3. extracellular matrix - withstand weight and endure abuse; formed by ground substance and fibers

3 structural elements of connective tissue

1. ground substance

2. fibers

3. cells

ground substance

unstructured material that fills the space between the cells and contains the fibers

composed of interstital fluid, cell adhesion proteins, GAG's (proteoglycans) (more GAG = stiffer ground substance)

fibers of connective tissue

collagen

elastic

reticular

collagen

formed by protein collagen

high tensile strength

white fibers

elastic fibers

thin, branched fibers

formed by elastin

found where elasticity is needed

yellow fibers

reticualr fibers

fine collagenous fibers

branch extensively forming networks that surround small blood vessels and support the soft tissue of organs

connective tissue proper cell type

fibroblast

cartilage cell type

chondroblast

bone cell type

osteobalst

blood cell type

hematopoietic stem cell

embryonic connective tissue

1. mesenchyme - first tissue formed from mesoderm

2. mucous connective tissue - forms whartons jelly of umbilical cord

areolar connective tissue

loose connective tissue proper

structure: cells (fibroblasts, WBC's mast, macrophages), fibers (collagen, elastic, and reticular) criss-crossing

function: supports and binds tissue, holds body fluids, defends against infection, stores nutrients as fat

location: epithelial basement membranes rest on this, attaches skin to underlying tissue

adipose tissue

loose connective tissue proper

structure: cell (adipocytes), very few fibers, little extracellular matrix

function: nutrient storing, shock absorber, insulator, supports and binds other tissue

location: subcutaneous areas, mammary glansds

reticular connective tissue

loose connective proper

structure: cell (fibroblast, WBC's, macrophages, mast) fiber (reticular)

function: forms stroma or internal framework of many organs (mainly immune), support many blood cells

location: spleen, lymph, and bone marrow

dense regular collagenous

dense regular connective proper

structure: collagen fibers in somewhat the same direction

function: able to withstand great pulling forces, tensile strength, stretch resistance

location: tendons and ligaments

dense regular elastic

dense regular connective tissue proper

structure: collagen and elastic fibers

function: able to stretch and recoil but strength in direction of the fibers

location: vocal folds

dense irregular collagenous

dense irregular connective tissue proper

structure: collagen fibers that run in all planes

function: able to withstand stretching in all directions

location: dermis of skin, joint capsules and organ cpsules

dense irregular elastic

dense irregular connective tissue proper

structure: collagenous and elastic fibers in multiple directions

function: strength, stretching and recoiling in many directions

location: elastic arteries

cartilage

Resist tension and compression

Avascular

Lacks nerve

Large amount of GAG

Chondroblasts (chondrocytes in lacumae)

Hyaline cartilage

Most abundant

Structure: chondroblast, a lot of GAG, collagen

Function: strong support, flexibility

Location: nose, ribs, end of bones, growth plate of bones

Elastic cartilage

Structure: chondroblast, a lot of GAG, elastic fibers

Function: rigid but elastic

Location: ear, epiglottis

Fibrocartilage

Structure: collagen fibers, more fibrous than hyaline

Function: slightly compressible, very tough

Location: joints with a lot of pressure (knee, jaw, between vertebrae)

Osteoblast

Produce organic portion of the matrix

Osteocalst

Break down previously existing bone

Osteocyte

Mature bone cell, reside in lacunae

Bone tissue

3 cell types: osteoblast, osteoclast, osteocyte

Structure: osteoblast, collagen, matrix (inorganic calcium salts)

Function: supports and protects, fat storage, make blood

Location: bones

Blood tissue

Structure: cells (RBC's, WBC's, and patelets), fibers (fibrin), ground substance (plasma)

Epithelial membranes

Covering and linings - considered simple organs because they incorporate both epithelium and connective tissue.

4 types of epithelial membranes

1. Cutaneous membrane

2. Mucous membrane

3. Serous membrane

4. Synovial membrane

Cutaneous membrane

Skin

2 layer:

Keratinized stratified squamous epithelium (epidermis)

Dense irregular connective tissue (dermis)

Dry membrane

Mucous membrane

Line body cavities that open to the exterior (digestive and respiratory)

Wet or moist

Mucosa refers to location and not composition

2 layers:

Epithelial - simple columnar or stratified squamous

Areolar - forms the lamina propria

Function: absorption and secretion

Serous membranes

Moist membranes that line the ventral body cavity

Secrete serous fluid (lubricates the faces of the parietal and visceral layers so they can slide across one another

Serous membranes formed by:

1. Mesothelium - simple squamous

2. Areolar connective tissue

2 layers of serous membranes

1. Parietal layer - lines the cavity

2. Visceral layer - lines the organ

3 sets of serous membranes

1. Pleural membranes - lungs

2. Pericardial membranes - heart

3. Peritoneal membranes - abdominal cavity

Nervous tissue

Main component of the nervous system

Neurons - nerve cells that generate and conduct nervous impulses

Supporting cells - nonconducting cells. Provide support, insulation, and protection to the neurons

3 types of muscle tissue

1. skeletal

2. cardaic

3. smooth

skeletal muscle

striated

cells are straight but not branched

cells are multinucleated

cells are voluntary

structure: striated, long, cylindrical

function: moves body voluntarily

location: attached to bone or connective tissue

cardiac muscle

striated

cells are branched

uninucleated

involuntary control

structure: cylindrical, striated, branched

function: pumps blood

location: heart

smooth muscle

found in walls of hollow organs involuntary control

structure: not striated, spindle shaped, uninucleated,

function: forces fluid through tubes, regulates size of organs

location: in hollow organs (stomach, intestines)

regeneration

replacement of destroyed tissue with the same kind of tissue

fibrosis

replacement of destroyed tissue with fibrous connective tissue (scar tissue)

3 steps of tissue repair

1. inflammation - clear the debris from a clot (red, hot, swelling)

2. organization restores blood supply (blood clot replaced granulation tissue which contains blood vessels and fibers)

3. regeneration and fibrosis effect permanent repair (epithelium regenerates and underlying area forms a scar)