Cells and TissuesCells and Tissues

Chapter 3Chapter 3

CellsCells

Cells are the smallest living thing.Cells are the smallest living thing.

MembraneMembrane

MembranesMembranes

The cells connection to the outside world.The cells connection to the outside world.

Absorption done through membrane.Absorption done through membrane.

Microvilli found in places where absorption Microvilli found in places where absorption takes place. takes place.

Membrane JunctionsMembrane Junctions

Where two cells come together.Where two cells come together.Tight Junctions – keep things water tight. Tight Junctions – keep things water tight. Sm. IntestineSm. IntestineDesmosomes – Keeps cells together that Desmosomes – Keeps cells together that are constantly under mechanical stress. are constantly under mechanical stress. Skin. Uses protein filaments to increase Skin. Uses protein filaments to increase stabilitystabilityGap Junctions – Allows for passing of Gap Junctions – Allows for passing of materials from adjacent cells.materials from adjacent cells.

Membrane JunctionsMembrane Junctions

TissuesTissues

Group of cells with similar structure and Group of cells with similar structure and functionfunction

Epithelium (covering), connective Epithelium (covering), connective (support), nervous (control), and muscle (support), nervous (control), and muscle (movement). (movement).

Nervous Tissue

Nervous Tissue helps to control the body and pass signals from one organ to another.

Muscle TissuesMuscle Tissues

Skeletal muscle – Connected to bones for Skeletal muscle – Connected to bones for voluntary movement. Long striationsvoluntary movement. Long striations

Cardiac muscle – tissues of the heart. Cardiac muscle – tissues of the heart. Striated like skeletal muscle, but shorter in Striated like skeletal muscle, but shorter in length. length.

Muscle tissuesMuscle tissues

Smooth muscle – no striations, found in Smooth muscle – no striations, found in hollow organs. Stomach, intestines, etc. hollow organs. Stomach, intestines, etc.

Epithelial TissueEpithelial Tissue

Protection, absorption, filtration and Protection, absorption, filtration and secretionsecretionCharacteristicsCharacteristics– Close together, make sheetsClose together, make sheets– Apical (free) surfaceApical (free) surface– Rests on basement membrane (bottom)Rests on basement membrane (bottom)– Avascular – no blood vessels, depends on Avascular – no blood vessels, depends on

diffusion for oxygen and fooddiffusion for oxygen and food– Regenerate quickly. Regenerate quickly.

Epithelial tissueEpithelial tissue

Two types, simple (one layer) vs Stratified Two types, simple (one layer) vs Stratified (many layers)(many layers)

Squamous – flat cells that fit together like Squamous – flat cells that fit together like floor tiles, making a flat sheet. Lung and floor tiles, making a flat sheet. Lung and esophogus tissueesophogus tissue

Epithelial TissueEpithelial Tissue

Cuboidal – thicker then squamousCuboidal – thicker then squamous

Columnar – elongated cellsColumnar – elongated cells

Connective TissuesConnective Tissues

Protects, supports, and binds tissues Protects, supports, and binds tissues together. together.

CharacteristicsCharacteristics– Vascularized – most have good blood supplyVascularized – most have good blood supply– Extracellular Matrix – nonliving substances Extracellular Matrix – nonliving substances

outside of cells that help perform functionoutside of cells that help perform functionCells make fibers that hold water, making Cells make fibers that hold water, making connective tissue very durable. connective tissue very durable.

Types of Connective TissueTypes of Connective Tissue

Bone – cells surround by an extremely Bone – cells surround by an extremely hard matrix that contains calcium and hard matrix that contains calcium and collagen.collagen.

Types of Connective TissueTypes of Connective Tissue

Cartilage – more flexible then bone (matrix Cartilage – more flexible then bone (matrix is softer). Mostly collagen, between bonesis softer). Mostly collagen, between bones

Types of Connective TissueTypes of Connective Tissue

Dense connective tissue – collagen with Dense connective tissue – collagen with fibroblasts. Tendons, ligaments, and fibroblasts. Tendons, ligaments, and lower skin layerslower skin layers

Types of Connective TissueTypes of Connective Tissue

Loose Connective Tissue – softer with Loose Connective Tissue – softer with fewer fibers fewer fibers

Areolar Tissue – most abundant, keeps Areolar Tissue – most abundant, keeps organs in place as well as stores water organs in place as well as stores water and saltsand salts

Adipose tissue – areolar tissue that has Adipose tissue – areolar tissue that has lipid containing cells in it. lipid containing cells in it.

BloodBlood

Considered to be connective because it is Considered to be connective because it is a cell (erythrocyte) surrounded by a matrix a cell (erythrocyte) surrounded by a matrix (blood plasma). (blood plasma).

Fibers in matrix are only visible during Fibers in matrix are only visible during clottingclotting

Tissue RepairTissue Repair

Three levelsThree levels– Skin and mucus protect the body from the Skin and mucus protect the body from the

outside environment.outside environment.– In case of injury, inflammation occurs to help In case of injury, inflammation occurs to help

stop any further damage.stop any further damage.– Regeneration begins to fix broken or lost Regeneration begins to fix broken or lost

tissuetissue

RegenerationRegeneration

Capillaries open - allows clotting materials Capillaries open - allows clotting materials to exit blood stream and enter the wound. to exit blood stream and enter the wound. Clotting agents seal the wound and stop Clotting agents seal the wound and stop outside invaders from entering the body. outside invaders from entering the body.

Granulation tissue forms – pink tissue, Granulation tissue forms – pink tissue, mostly capillaries, that bring proteins to the mostly capillaries, that bring proteins to the wound site for regeneration. Bleeds freely wound site for regeneration. Bleeds freely (picking a scab before it is fully healed)(picking a scab before it is fully healed)

RegenerationRegeneration

Surface epithelium regenerates – Surface epithelium regenerates – granulation tissue gives way to brand new granulation tissue gives way to brand new epithelium tissue and scar tissue.epithelium tissue and scar tissue.

Skin and mucous membranes heal very Skin and mucous membranes heal very nicely, usually no scaring. nicely, usually no scaring.

Muscle and nervous tissue heal poorly or Muscle and nervous tissue heal poorly or not at all. not at all.

Tissues over timeTissues over time

During childhood and adolescence the During childhood and adolescence the body is growing and almost all tissues are body is growing and almost all tissues are multiplying. multiplying.

After adolescence, this changes.After adolescence, this changes.

Some tissues continue to reproduce Some tissues continue to reproduce normally, skin, intestines etcnormally, skin, intestines etc

Some stops, but can start again. LiverSome stops, but can start again. Liver

Some stops completely. heartSome stops completely. heart

AgingAging

Aging caused by Aging caused by – ToxinsToxins– RadiationRadiation– Genes (telomeres)Genes (telomeres)

Skin loses elasticity and sagsSkin loses elasticity and sags

Bones become porous and weakerBones become porous and weaker

Muscles Atrophy due to lack of useMuscles Atrophy due to lack of use

NeoplasmNeoplasm

Abnormal mass that grows when unneeded, aka Abnormal mass that grows when unneeded, aka tumor.tumor.

Benign – grow in a capsule that does not allow Benign – grow in a capsule that does not allow for cells to migrate, only dangerous if not for cells to migrate, only dangerous if not removed before it gets so large that it pushes on removed before it gets so large that it pushes on important organs.important organs.

Malignant – not in a capsule, can Metastasis Malignant – not in a capsule, can Metastasis and travel around the body. Grows into good and travel around the body. Grows into good tissue causing functionality problems. tissue causing functionality problems.