Ch. 4 - Tissues

What is the definition of a tissue?

a group of cells that are similar in structure and perform a common or related function

Functions of epithelial tissues? (how epithelia are modified for some functions)

• Protection (many layers, desmosomes)

• Absorption (tight junctions, simple, microvilli)

• Filtration (simple)

• Secretion (simple)

• Exchange (simple, flat cells)

5 properties of epithelial tissue

• polarity (apical/basal)

• specialized cell-cell contacts (junctions)

• supported by underlying connective tissues (epithelial + connective)

• avascular but innervated

• regenerative

2 layers that make up basement membrane?

basil lamina (epithelial) and reticular lamina (connective)

cilia? microvilli? structure/function differences? where are they found?

cilia are extensions that propel substances across the membrane, microvilli increase surface area for diffusionand providing nutrients

cilia found in trachea/respiratory tract, microvilli found in uterine tubes and small bronchi of lungs

what does avascular mean? innervated?

avascular means no blood supply, innervated means nerve endings

how are epithelial tissue named? what do you look for?

simple/psuedostratified and stratified is single layer/multiple layers, cuboidal (cube, circle nucleus) columnar (column and oval nucleus) and squamous (flat, scale) like are shape

structure and functions of simple squamous

simple, thin, flat layer of cells for absorption, filtration, secretion, and exchange - air sacs (diffusion) kidney glomeruli (filtration) walls of capillaries/endothelium (gas exchange)

structure and functions of simple cuboidal

simple, cubed for absorption, secretion - small glands, kidney tubules, ovaries

structure and functions of simple columnar

simple, columnar/long for absorption, secretion of mucus (ciliated or non) - digestive tract (microvilli not cilia) small bronchi of lungs + uterine tubes (ciliated)

structure and functions of psuedostratified columnar

looks like multiple layers for secretion, propel (ciliated) - upper respiratory tract (trachea) to propel mucus away from lungs in one direction

structure and functions of stratified squamous

several layers (top dead keratinized (tough, fibrous)) protection - skin (dry), mouth, esophagus, vagina (all wet)

structure and functions of transitional

change shape depending on degree of organ stretch - urinary system organs (basal cells will look column/cube, apical cells squamous-like when stretched)

What are glands?

a single cell or a group of cells that make and secrete substances into ducts, onto a surface, or into the blood

How are glands classified?

endocrine glands: secrete substances (hormones) into blood

exocrine glands: secrete substances onto body surfaces or into cavities

Main difference between exocrine and endocrine?

endocrine secretes into blood, while exocrine are onto surfaces and cavities

Endocrine / exocrine gland examples:

endocrine: testes/ovaries, pituitary, pineal, adrenal, thyroid, pancreas

exocrine: sweat glands, oil, salivary, pancreas

Two modes of secretion of multicellular exocrine glands - how are they different?

Merocrine: glands secrete products by exocytosis (pancreas, sweat, salivary)

Holocrine: accumulate product until rupture (oil glands)

Types of connective tissues and their functions?

Connective tissue proper, cartilage, bone, blood - support, protection, insulation, fuel storage, transport

Common characteristics of connective tissues - how are they different to epithelial

• all types arise from same embryonic tissue (mesenchyme)

• various degrees of vascularity (blood supply)

• composed of “living” cells and a “non-living” extracellular matrix

Which connective tissues are vascular, avascular?

Cartilage is poorly vascular (low blood supply), and bone, adipose is highly vascular (high blood supply)

Where do all connective tissues originate?

the same embryonic tissue (mesenchyme)

How does function of immature and mature cells of connective tissue differ?

immature are actively dividing, fast mitosis, secrete ECM, -blast

mature have slow mitosis, maintain health of ECM, carry out specialized function, -cyte

What is the resident cell type of each type of connective tissue?

fibro- (connective tissue proper), chondro- (cartilage), osteo- (bone)

What is found in the extra cellular matrix of connective tissue?

Ground substances (fills space between cells, ECF)

Fibers (in ground substance)

• collagen (high tensile strength)

• elastic (allows stretch)

• reticular (support soft tissues/small blood vessels)

• functions to provide support

macrophage, fibroblast, lymphocyte, fat cell, mast cell, neutrophil, capillary

Various tissue types of connective tissue proper… “loose” or “dense”?

loose

• adipose

• areolar

dense

• regular

• irregular

• elastic

Structure and functions of loose areolar - where do you find them?

gel-like matrix with all 3 fiber cells, wraps and cushions organs, support, immune, inflammation, fluid reservoir (edema: fluid retention in areolar tissue)

• under epithelia of body, surrounds capillaries, packages organs

Structure and functions of adipose - where do you find them?

Closely packed adipocytes (store lipids), little matrix and is highly vascularized, insulates, reserves fuel, supports/protects, in subcutaneous tissue (around kidneys/eyeballs, abdomen, breasts)

Structure and functions of dense regular - where do you find them?

Few cells, little ground substance, lots of collagen fibers running parallel in one direction, poorly vascularized (high tensile strength in one direction) - tendons, ligaments, aponeuroses

Structure and functions of dense irregular - where do you find them?

Few cells, very little ground substance, less vascular, high tensile strength when pulled in many directions, withstands tension - dermis of skin

Compare and contrast: intradermal, subcutaneous, intramuscular injections?

• Target tissue, injection angle, drugs administered

Intradermal: Into dermis, easily visible, TB/allergy tests, 15 angle

Subcutaneous: into adipose tissue just below skin, insulin, 45 or 90 angle

Intramuscular: through skin and subcutaneous into underlying muscle, 90 angle, antibiotics/hormones/vaccines/EpiPen

Structure and functions of hyaline cartilage - where is it found/most abundant, strong/weak?

Most abundant, flexibility and support while absorbing some shock, weakest in the body, ends of long bones and embryonic skeleton (also nose and trachea)

Structure and functions of fibrous cartilage - where is it found/most abundant, strong/weak?

Strongest in the body (thick and many collagen fibers), strong support and withstands heavy pressure but less flexible, in intervertebral discs, pubic symphysis, discs of knee

Structure and functions of elastic cartilage - where is it found/most abundant, strong/weak?

Same structure as hyaline but more elastic fibers, external ear and epiglottis, no nerve endings or blood supply, weak

Structure and functions of bone tissue (how is different from cartilage?)

Extra collagen fibers and inorganic calcium salts in matrix for bone to support and protect body structure, highly vascularized, hematopoiesis, fat storage

Structure and function of blood, why is it classified as connective?

Transport, red/white blood cells in plasma, within blood vessels, connects all system and transports

Structure and functions of skeletal muscle and nerve tissue

Skeletal: Voluntary movement, thermoregulation/locomotion, striations (skeletal muscles/some skin)

Nerve: Communication, electrical signals (brain, spinal cord, nerves)

How do skeletal, smooth, and cardiac muscles differ in terms of where they are found and nervous system control?

Skeletal: voluntary; skeletal muscles/skin

Cardiac: involuntary; heart

Smooth: involuntary; vessels, digestive

Difference between neurons and neuroglia?

Neurons: generate nerve impulses

Neuroglia: no nerve impulses; support, insulate, protect neurons

Describe regenerative capacity of epithelia, connective tissue, cartilage, muscle, and nervous tissue

High: epithelial

Moderate: tendons + ligaments

Weak: cartilage

Little/no: nervous tissue + cardiac (forms scar tissue)