© 2012 Pearson Education, Inc. Tissues A tissue is a group of cells with a common function Four...

© 2012 Pearson Education, Inc.

Tissues

• A tissue is a group of cells with a common function

• Four primary tissues:– Epithelia– Connective tissues– Muscle– Nervous


Epithelial Tissues

• Line body cavities, cover surfaces (i.e.: skin)

• Also are the interior lining of: blood & lymph vessels, heart, G.I. tract, respiratory tract, genital & urinary tracts.

• Everything that goes into the body will have to pass through epithelium.


Glandular epitheliaEpithelial cells adapted to make up glands-Exocrine glands

Secrete into ducts to exterior of body

-Endocrine glandsSecrete into the blood to carry chemical messages throughout the body


Epithelial Tissues: Classification

• Shape– Squamous

• Flattened cells• Line vessels, part of lungs, body surface

– Cuboidal• Cube shaped• Form lining of tubules, glandular tissue

– Columnar• Column shaped• Line respiratory, digestive, reproductive tracts


Epithelial Tissues: Classification

• Number of layers– Simple/single–layered

• Adapted for diffusion across cell barriers• Line glands, and respiratory, digestive, urinary,

& reproductive systems

– Stratified/multiple–layered• Provide protection, as in the skin surface

© 2012 Pearson Education, Inc. Figure 4.1a

Simple squamous• Lines blood vessels and air sacs of lungs• Permits exchange of nutrients, wastes, and gases

Stratified squamous• Outer layer of skin, mouth, vagina• Protects against abrasion, drying out, infection

Stratified cuboidal• Lines ducts of sweat glands• Secretes water and ions

Simple cuboidal • Lines kidney tubules and glands • Secretes and reabsorbs water and small molecules

Simple columnar • Lines most digestive organs • Absorbs nutrients, produces mucus

Goblet cell Basement membrane

Stratified columnar• Lines epididymus, mammary glands, larynx• Secretes mucus

a) Most epithelial tissues line or cover surfaces or body cavities.

© 2012 Pearson Education, Inc. Figure 4.1b

Exocrine gland

Gland cells

Endocrine gland

Gland cellsBlood flow

b) Glandular epithelia secrete a product.


The Basement Membrane Provides Structural Support for Epithelia

• Basement membrane– Provides structural support to overlying cells– Attaches epithelial layer to underlying tissues

• Junctions: hold epithelial cells together– Tight junctions

• Nothing passes

– Adhesion junctions/spot desmosomes• Some movement between cells

– Gap junctions• Protein channels


Tight junction proteins

Intercellular space

a) Tight junctions form leak-proof seals between cells


Protein filaments

Intercellular space

b) Adhesion junctions anchor two cells together, yet allow flexibility of movement

© 2012 Pearson Education, Inc. Figure 4.2c

Protein channel

Intercellular space

c) Gap junctions provide for the direct transfer of water and ions between adjacent cells


Connective Tissue

• General functions– Supports softer organs of body– Connects parts of body– Stores fat– Produces blood cells

• Contains cells embedded in nonliving extracellular matrix

• Matrix provides the strength

• Two general types of connective tissue– Fibrous and special


Fibrous Connective Tissue

• Function: provides strength and elasticity

• Contains fibers and cells embedded in gel-like ground substance (matrix)

• Matrix: intercellular material giving the CT its characteristics

• Cells: fibroblasts (function is to make the protein fibers & matrix), macrophages, lymphocytes, and neutrophils

• Fibers: collagen, elastic, and reticular


Fibrous ConnectiveTissue

• Four general types– Loose: surrounds many organs, lines

cavities around blood vessels– Dense: forms tendons, ligaments, deeper

layers of skin– Elastic: surrounds stomach, bladder,

arteries, maintains shape– Reticular: makes up internal framework of

soft organs (liver) and the lymphatic system

© 2012 Pearson Education, Inc. Figure 4.3

Ground substance

Plasma cell

Neutrophil

Collagen fiber

Lymphocyte

Nerve fiber

Macrophage

Reticular fiber

Elastic fiber

Mast cell Fibroblast

Fat cell Capillary


Elastin fibers

Fibroblast

Collagen fibers

a) Loose (areolar) connective tissue (X 160). In loose connective tissue the collagen and elastin fibers are arrayed in a random

pattern.


Collagen fibers

Nuclei of fibroblasts

b) Dense connective tissue (X 160). In dense connective tissue the fibers are primarily collagen fibers. In tendons and ligaments the fibers are oriented all in the same direction, with fibroblasts occupying narrow spaces between adjacent fibers.


Specialized Connective Tissues Serve Special Functions

• Cartilage: produced by chondroblasts (which are found in lacunae); no blood vessels; high collagen content

• Bone: inorganic matrix with calcium salts for hardness

• Blood: fluid matrix of plasma, red blood cells, white blood cells, and platelets

• Adipose tissue: fat cells; function in insulation, protection, and energy storage


Chondrocyte in lacuna

Ground substance

a) Cartilage from the trachea (X 300). Mature cartilage cells, called chondrocytes, become trapped in chambers called lacunae within the hard, rubbery ground substance. Ground substance is composed of collagen fibers, polysaccharides, proteins, and water.


Vacuole containing stored fat

Blood vessel

Nuclei of fat cells

b) Adipose tissue from the subcutaneous layer under the skin (X 140). Adipose tissue consists almost entirely of fat cells. The fat deposit within a fat cell can become so large that the nucleus is pushed to the side.


Muscle Tissue Contracts to Produce Movement

• Skeletal muscle– Moves body parts– Voluntary, multinucleated

• Cardiac muscle– Functions in the heart– Involuntary, single nucleus

• Smooth muscle– Surrounds hollow structures– Involuntary, single nucleus


Nuclei

Width of one muscle cell

a) Skeletal muscle (X 100). Skeletal muscle cells are very long and have many nuclei.


Intercalated discNucleus

b) Cardiac muscle (X 225). Cardiac muscle cells interconnect with each other.

© 2012 Pearson Education, Inc. Figure 4.6c

Smooth muscle cell

Nucleus

c) Sheet of smooth muscle (X 250). Smooth muscle cells are thin and tapered.


Nervous Tissues Transmit Impulses

• Neuron: specialized nervous system cell– Function: generate and transmit electrical

impulses– Structural components: cell body, dendrites,

axon

• Glial cells support neurons


Axon

Nuclei of glial cells

Cell body

Dendrites


Organs and Organ Systems Perform Complex Functions

• Organs– Contain two or more tissue types joined

together; perform specific functions

• Organ systems– Groups of organs that perform a common

function– Examples

• Digestive system: mouth, throat, stomach, intestines, and liver

• Lymphatic system: lymph nodes, tonsils, and spleen


Body Cavities

• Anterior cavity– Thoracic cavity

• Two pleural cavities (1 for each _________)• Pericardial cavity (for the __________)

– Abdominal cavity

• Posterior cavity– Cranial cavity (for the ____________)– Spinal cavity (for the ________ ______)

• Epithelial tissue membranes (called serous membranes) line anterior body cavities


Pelvic cavity

Abdominal cavity

Anterior cavity

Diaphragm separates thoracic and abdominal cavities

Pleural cavity

Pericardial cavityThoracic

cavity

Posterior cavity

Vertebral canal

Cranial cavity


Tissue Membranes

• Serous membrane: reduces friction between organs

• Mucous membrane: lubricates surface, captures debris

• Synovial membrane: lines spaces in movable joints, lubricates the joint

• Cutaneous membrane: skin


The Skin as an Organ System

• The proper name is integumentary system

• Includes skin, hair, nails, glands

• Functions – Prevents dehydration – Protects from injury – Serves as defense against microorganisms– Regulates body temperature – Makes vitamin D – Provides sensation

© 2012 Pearson Education, Inc. Figure 4.10ReceptorsNerveSweat gland

Adipose tissue

Smooth muscle

VeinArtery

Sebaceous gland

Hypodermis

Dermis

Epidermis

Small blood vessels

Hair shaft Free nerve endings

Hair root

Hair follicle


Skin Consists of Epidermis and Dermis

• Epidermis– Outer layer – Stratified squamous epithelial cells – No blood vessels – Two major cell types

• Specialized keratinocytes• Melanocytes


Dead cells of epidermis

Living cells of epidermis

Dermis with blood vessel

Keratinocyte containing melanin

Melanocyte containing melanin granules

Dividing keratinocyte (basal cell)

Basement membrane

Blood vessel


Skin Consists of Epidermis and Dermis

• Dermis– Lies underneath the epidermis– Supports tissues– Fibers

• Collagen• Elastic

– Cells• Fibroblasts• Mast cells• White blood cells• Fat cells


Accessory Structures of Dermis

• Hair – Shaft– Follicle

• Smooth muscle– Attached to hair follicle, raises hair to

upright position

• Oil glands/sebaceous glands– Secretion moistens and softens skin


Accessory Structures of Dermis

• Sweat glands– Secrete sweat, help in temperature regulation

• Blood vessels– Supply nutrients, remove waste, assist in

temperature regulation

• Sensory nerve endings– Detect heat, cold, touch, deep pressure,

vibration


Multicellular Organisms Must Maintain Homeostasis

• Maintenance of relative constancy of the conditions of the internal environment

• Negative feedback control system: deviations from normal are detected and counteracted

• Components of a negative feedback control system – Controlled variable– Sensor– Control center– Effector


SensorEffector

Control center

Controlled variable

Higher

Set point

Lower

a) An increase in the controlled variable causes events that lower the controlled variable toward its set point again.


Controlled variable

Higher

Set point

Lower

SensorEffector

Control center

b) A decrease in the controlled variable causes events that raise the controlled variable toward its set point again.


Negative Feedback Helps Maintain Core Body Temperature

• Controlled variable: body temperature

• Sensors: temperature sensors in skin and internal organs

• Control center: hypothalamus in the brain

• Effectors– Blood vessels– Sweat glands– Skeletal muscles


Core temperature Core temperature

Higher

Set point Set point

Higher

Lower Lower

Constriction of bloodvessels in skin(saves heat)

Dilation of bloodvessels in skin(promotes heat loss)

SensorsSensors

Shivering(generates heat) Sweating

Control center(hypothalamus)

Control center(hypothalamus)

to to

toto


Homeostasis

© 2012 Pearson Education, Inc. Tissues A tissue is a group of cells with a common function Four...

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