Chapter 5 (not done)

Four Primary Tissues

Connective, Epithelial, Muscle, Nervous

Epithelial tissue covers

all body surfaces (internal and external

Apical surface

faces external environment [e.g. lumen of intestinal tract, air side of

lungs, line blood vessels, skin]

Basal surface

side attached to basement membrane

vasculature

blood vessels

lacking or without

“a”

Muscular Tissue

connective tissue

Nervous tissue

Epithelial tissue

Epithelia are avascular

no blood supply [within the tissue]

Epithelia are innervated

have a nerve supply

Epithelia re—-

regenerate [regrow]

Epithelial tissue Function: Protection

prevents water loss (skin)

protects underlying tissues

resists physical stress

Epithelial tissue Function: Secretion

glands produce hormones, sweat, mucus

Epithelial tissue Function: Absorption

takes up material from the environment

(e.g., circulation, digestive tract, lungs)

Epithelial tissue Function: Filtration and selective movement

filtrate formation in kidney

transporters for specific molecules (e.g., glucose, ions)

Epithelial tissue Function: Excretion (one way waste products are released

movement of CO2 from blood into alveoli

sweat contains ammonia, urea, NaCl

Epithelial tissue Function: Sensation

nerve endings in detect pain (paper cut, stomach pain)

specialized cells detect changes in internal and external environments

Examples of Sensation in Epithelial tissue

Taste and smell, Touch and vibration

Epithelial tissue Function: Immune defenses

physical barrier

some cells of immune system here [additional protective function]

Epithelia can be classified according to

cell shape of the layer closest to the environment, and number of cell layers

Simple Epithelium

Squamous Cell

Columnar cell

Stratified Epithelium

One cell layer thick

simple epithelium

two or more cell layers thick

stratified epithelium

Pseudo

false

pseudostratified

falsely layered

Osteoblasts

build bone

Osteoclasts

Breakdown bone

Merocrine gland

secretions packaged into vesicles, released by exocytosis

e.g., Lacrimal (tear) and salivary glands

Apocrine gland

accumulates secretion in apical region of cell

apical membrane pinches off forming a vesicle containing the secretion

e.g., mammary and ceruminous glands

Holocrine gland

cell ruptures becomes part of secretion

e.g., sebaceous (oil) glands

Extensibility

a change in length [stretching]

allows stretching without breaking (~1 ½ increase

Elasticity

allows fibers return to resting length after stretching

Areolar connective tissue [all three fibers]

well vascularized

e.g., beneath skin, surrounds nerves and blood vessels

Reticular connective tissue [mostly reticular fibers]

e.g., lymph nodes, spleen, thymus, bone marrow

Dense regular - parallel collagen fibers

resistant to tension in one direction

fibroblasts between fiber bundles

little ground substance and few blood vessels

e.g., tendons and ligaments [one plane of movement]

Dense regular elastic connective tissue

mostly parallel-oriented elastic fibers

in walls of structures that stretch to perform their function,

e.g., large blood vessels near heart and certain ligaments

Dense irregular

random direction of collagen fibers) [disorganized fibers]

some open space with ground substance and some cells

strong and resists tension in all directions

e.g., dermis, fibrous sheath around bones, nerves, organs and joints

Two types of fat

white and brown

White adipose tissue

see one large lipid inclusion (triglycerides) in cytosol

cell size varies

fat storage (major energy reserve)

insulation (retains warmth)

shock absorption and protection

secretes hormones

[e.g., appetite regulation, reproduction, metabolism]

White adipose tissue

Brown adipose tissue

more in infants and children

brown color due to numerous mitochondria and rich blood supply

fat readily converted to energy to produce heat in cold temperatures amount increases in cold-acclimated adults

Chondroblasts

cells that synthesize extracellular matrix

Chondrocytes

mature, inactive chondroblasts

trapped in matrix spaces called lacunae

elastic fibers predominate

allows for flexibility and return to shape after stretching or deforming

Elastic cartilage

Liquid Connective Tissues

Blood and Lymph

Difference in fiber types is the

basis for subclassifications

hyaline, elastic and fibrocartilage

Endocrine glands

ductless and secrete products directly into interstitial fluid and bloodstream

products, usually hormones

systemic effects

[e.g., insulin and glucagon]

Exocrine glands

have ducts and release products onto an epithelial surface

(e.g., salivary and mammary glands

Serous glands

produce thin, watery fluids

[e.g. perspiration, milk, and tears]

Mucous glands

actually secrete mucin (glycoprotein), which absorbs water, forming mucus

[e.g., respiratory and digestive tracts]

Mixed glands

produce a mixture of secretions

[e.g., salivary glands –produce secretion that is both mucus and serous composition]

Goblet cells

unicellular exocrine gland, secrete mucus thick, sticky liquid that protects underlying epithelium

Examples: digestive and respiratory tract