Panda Wilson 1

Human Anatomy & Physiology

Chapter 5: Tissues

Panda Wilson 2

II. A. What are tissues? and C. What is the matrix?A tissue is a group of similar cells specialized to carry out a specific function• In addition to cells, all tissues include a non-living portion

called the extracellular matrix (composition of the matrix varies from tissue to tissue). The function of the extracellular matrix is: to support the cells within the tissue andto transmit signals from outside the cells into cells (these

signals influence how cells function

Panda Wilson 3

II. B. The major tissue types & their functions1. Epithelial – cover & protection of organs, to participate in

secretion, absorption, excretion of various substances, and sensory reception

2. Connective – bind body parts together, support & protect softer body parts, and produce blood cells

3. Muscle – produce movement by contraction & relaxation4. Nervous – sensory reception and transmitting impulses for

coordination, regulation, & integration of body functions

Panda Wilson 4

III. Epithelial Tissues

• Epithelial tissues cover body surfaces & organs; lines inner surface of body cavities and inner surface of hollow organs; compose glands.• Characteristics are:

Lack blood vessels so nutrients must diffuse into epithelium from underlying connective tissues; anchored to underlying connective tissue by a thin, non-living layer called the basement membrane (which is part of the extracellular matrix)

Panda Wilson 5

III. Epithelial Tissues

• Classified according to types of cells Squamous: thin, flattened cellsCuboidal: cube-shaped cellsColumnar: tall, elongated cells

• and number of cell layers: Simple: single layerStratified: two or more layersPseudostratified: a single layer of cells that appears to be layered

because the cell nuclei are a varying levels along a row of aligned cells

Panda Wilson 6

Squamous Epithelium

Simple Squamous Stratified Squamous

Panda Wilson 7

Cuboidal Epithelium

Simple Cuboidal Stratified Cuboidal

Panda Wilson 8

Columnar Epithelium

Simple Columnar Stratified Columnar

Panda Wilson 9

Pseudostratified vs Stratified

Pseduostratified Stratified

Panda Wilson 10

III. C. Simple Squamous Epithelium

2. Because substances easily pass through simple squamous epithelium, it is found where diffusion and filtration take place. For example:

• alveoli in lungs where gas exchange takes place•walls of capillaries, linings of blood & lymph vessels• covers membranes that line body cavities

Because it is so thin & delicate, simple squamous tissue is easily damaged.

Panda Wilson 11

III. D. Simple Cuboidal Epithelium

2. Simple cuboidal tissue covers the ovaries, lines most of the kidney tubules and the ducts of certain glands (ex: salivary, thyroid, pancreas, & liver)

3. The functions of simple cuboidal tissue are secretion and absorption and, in glands, secretion of glandular products.

Panda Wilson 12

III. E. Simple Columnar Epithelium

1. Simple columnar tissue is a single layer of elongated (more long than wide) cells that may, or may not, be ciliated (the cilia are in constant motion so they function to move objects along the surface if the tissue).

2. Ciliated simple columnar tissue lines the fallopian tubes from the ovaries to the uterus; non-ciliated simple columnar tissue is found in the digestive tract.

3. Ciliated cells aid in movement of substances; in the digestive tract, non-ciliated cells protects underlying tissues, absorbs nutrients, and secretes various fluids.

Panda Wilson 13

III. F. Pseudostratified Columnar Epithelium

Cilia are a characteristic of pseudostratified columnar epithelial which lines the passages of the respiratory tract.• The respiratory tract linings are mucous-covered & sticky in order

to trap dust and microorganisms entering with air. The cilia move the mucous & its captured particles upward and out of the respiratory airways.

Panda Wilson 14

III. G . Stratified Squamous Epithelium1. Cell division takes place in the deeper layers that are closer

to the basal membrane & the nutrient supply of the underlying connective tissue. the layers are pushed upward and outward as new cells are produced. As the cells move outward they become more flattened.

2. S. S. E. forms the outer layer of the skin, & is found in the lining of the oral cavity, throat, vagina, and anal canal.

Panda Wilson 15

III.H. Transitional Epithelium

• Transitional epithelium is specialized to change in response to increased tension (in other words, it “stretches”).• T. E. forms the inner lining of the urinary bladder (where it also forms

a barrier to prevent contents of the urinary system from diffusing back into the internal environment).• T. E. also lines the ureters (from kidney to bladder) and part of the

urethra (bladder to outside).

Panda Wilson 16

III.I. Glandular Epithelium

• Glandular epithelium is composed of cells that are specialized to produce & secrete substances into ducts or into body fluid. (Usually cuboidal or columnar epithelia.)

Note: exocrine vs endocrine glands• Exocrine glands secrete their products into ducts that open

onto surfaces (such as the skin or the lining of the digestive tract).• Endocrine glands secrete their products into tissue fluid or

blood.

Panda Wilson 17

III.J. Types of Glandular Secretions•Merocrine

a water, protein-rich fluid product is released through the cell membrane by exocytosis

ex: salivary glands, sweat glands, pancreatic glandsmerocrine glands release secretions without losing any of

the cell’s cytoplasm

Panda Wilson 18

III.J. Types of Glandular Secretions•Apocrine

The secretions apocrine glands consist of cellular product & portions of the free end of glandular cells is released through the cell membrane by exocytosis

ex: mammary glands, ceruminous glands lining the external ear canal

apocrine glands lose small portions of their bodies during secretion

Panda Wilson 19

III.J. Types of Glandular Secretions•Holocrine

entire cells filled with secretory products disintegrateex: sebaceous glands of the skin

Panda Wilson 20

IV. Connective Tissues: Structure &Characteristics• cells are farther apart than epithelial cells & have an

abundance of extracellular matrix (consistence varies from fluid to semisolid to solid)• can usually divide• varying degrees of vascularity (blood vessels) but usually have

good blood supplies and are well nourished• Types: bone (most rigid), cartilage (less rigid than bone), dense

connective tissue (more flexible; ex: tendons & ligaments), adipose tissue, loose connective tissue (aka areolar tissue), blood (fluid)

Panda Wilson 21

IV. A. Connective Tissues: Functions

• bind structures• provide support & protection• serve as frameworks• store fat• produce blood cells• protect against infections• help repair tissue damage

Panda Wilson 22

IV. Connective Tissues: Components of Connective Tissue

Cell Type• Fibroblast – produce fibers•Macrophages – carry on

phagocytosis•Mast cells – secrete heparin

& histamine

Tissue Fiber• Collagenous –tensile

strength• Elastic – stretches• Reticular – very thing

collagenous fibers that provide net-like, delicate support networks

Panda Wilson 23

IV. B. Connective Tissues: Cell Type Functions• Fibroblast

most common “fixed” cells (fixed = not mobile)produce fibers by secreting protein into the matrix

• Macrophagesaka histiocytes; begin as white blood cellsact as scavengers & defensive cells against foreign particles; they are

phagocytes (“eat” cell!! – engulf & break down foreign particles)

• Mast cellsvery large cells found near blood vesselsrelease heparin (prevents blood clotting) & histamine (promotes reactions

associated with inflammation & allergies)

Panda Wilson 24

IV. C. Collagenous vs Elastic

•Collagenous FibersVery strong which allows the tissues to withstand pulling forcesLittle ability to stretch

• Elastic FibersGreat ability to stretchNot as strong as collagenous fibers

Note: blood supply to dense connective tissue (make up tendons & ligaments) is poor = SLOW to heal

Panda Wilson 25

IV. D. Ligament vs Tendon

Note: blood supply to dense connective tissue (make up tendons & ligaments) is poor = SLOW to heal• BOTH are collagenous fibers• Ligaments connect bones to bones• Tendons connect muscles to bones

Panda Wilson 26

IV. E. Adipose Tissue

• Specialized form of loose connective tissue that develops when fat droplets are stored in the cytoplasm of adipocytes• Lies beneath the skin between muscles, around the kidneys, behind

the eyeballs, in certain abdominal areas, on the surface of the heart, and around certain joints.• Adipose tissue cushions joints & some organs (ex: kidneys); it also

provides insulation and energy storage (in fat molecules)

Panda Wilson 27

IV. F. Types of CartilageGeneral Characteristics• A rigid connective tissue that provides support, frameworks,

and points of attachment ; also forms structural models for many developing bones• Has no direct blood supply; nutrients diffuse into cartilage

from surrounding perichondrium This is reason that torn cartilage heals slowly and why chondrocytes do not

divide frequently

Panda Wilson 28

IV. F. Types of Cartilage•Hyaline cartilage

Most common; very fine fibers (looks ~ like white glass)Found on the ends of bones in many joints, soft part of

the nose, & in the supporting rings of the respiratory passages

Function to cushion shock in joints and as a model for development & growth of some types of bone)

Panda Wilson 29

IV. F. Types of Cartilage• Elastic cartilage

More flexible than hyaline due to having a network of elastic fibers

Provides the flexible framework for external ear (pinna) and the larynx

• FibrocartilageVery toughActs as a shock absorber for structures subject to pressure;

for ex: forms pads (intevertabral disc )between vertebrae and cushions bones in the knee and pelvic girdle

Panda Wilson 30

IV. G. Bone

1. Bone is the most rigid of the connective tissues:• Hardness due to the deposition of mineral salts between the

cells• Functions are:

supports body structure protect vital body parts provide points of attachment for muscles (making movement possible) Contains red marrow which forms blood cells and maintains calcium &

phosphorus balance

2. Bone injuries heal relatively quick

Panda Wilson 31

IV. G. Bone

2. Bone injuries heal relatively quick because of good blood supply. (The central canal of bones contains a blood vessel.)

Panda Wilson 32

IV. H. Blood (Vascular Connective Tissue)1. Blood is composed of formed elements (cells)

suspended in a fluid extracellular matrix called blood plasma.

2. The formed elements (cells) are • red blood cells (RBCs)•white blood cells (WBCs)• platelets (cell fragments)

Panda Wilson 33

IV. H. 3. Connective Tissue Matrix

The connective tissue matrix is the key to connecting cells to tissues:• it is composed of the basement membrane and the interstitial matrix

(the material between cells)• serves as a scaffolding to organize cells into tissues• it relays biochemical signals that control cell division, differentiation,

movement, & migration.

Panda Wilson 34

V. Muscle

A. The characteristic of muscle tissue is its ability to contract (shorten) in response to stimuli. As they contract, the muscle fibers pull at their attached ends and thus move body parts.

Panda Wilson 35

V. Muscle

Skeletal muscle• long, thread-like cells that have alternating light & dark

striations • controlled by conscious effort (hence the alternative

description of “voluntary muscle”)• Skeletal muscle is found in muscles that attach to bone

allowing body movement

Panda Wilson 36

V. Muscle

Smooth muscle• no striations, shorter than skeletal muscle cells and are more

spindle-shaped• not controlled by conscious effort – its actions are involuntary • comprises the walls of hollow organs such as the stomach,

intestine, urinary bladder, uterus, and blood vessels•Moves food through the digestive tract, constricts blood

vessels, and empties the urinary bladder

Panda Wilson 37

V. Muscle

Cardiac muscle• Striated and branched; are joined end-to-end forming

complex networks• not controlled by conscious effort – its actions are

involuntary • comprises the bulk of the heart• pumps blood through the heart chambers and into blood

vessels

Panda Wilson 38

VI. Nervous Tissue

A. The basic cell of nervous tissue is the neuron.B. Neuroglial cells support and bind cells, carry on

phagocytosis, & help supply nutrients to nerve cells by connecting them to blood vessels.

C. Nervous tissue senses changes in the internal & external environment, interprets those changes, and responds by sending impulses to effectors (such as muscles, glands, or organs)

Panda Wilson 39

VII. Membranes

Membranes are considered organs because they are comprised of at least two kinds of tissues. There are 3 major types of membranes:

1. Serous membranes2. Mucous membranes3. Cutaneous membranesA fourth type of membrane, synovial membrane, lines joints such as

the knee.

Panda Wilson 40

VII. Membranes• Serous membrane

Lines body cavities that lack opening to the outside; form the lining of the thorax (parietal pleura), and abdomen (parietal peritoneum), and the organs within these cavities (visceral pleura & peritoneum)

•Mucous membraneline cavities that open to the outside of the body; ex: oral & nasal

cavities and the tubes of the digestive, respiratory, urinary, & reproductive systems

mucous membranes contain goblet cells that secret mucus

Panda Wilson 41

VII. Membranes•Cutaneous membrane is more commonly referred to

as the skin.