Objective: ◦ To understand how cells combine to form tissues◦ To differentiate between types of tissues

Journal: What are the levels of organization that are found in an organism?

September 30, 2014

Cells

Cells are the smallest unit of life that can carry out all of the processes of life.

Some organisms are so simple, they are only made up of one cell

Humans are multicellular

Introduction To The Cell

1. ALL LIVING THINGS ARE COMPOSED OF ONE OR MORE CELLS.

2. CELLS ARE AN ORGANISMS’ BASIC UNIT OF STRUCTURE AND FUNCTION

3. CELLS COME FROM OTHER CELLS

Cell Theory

SIZE - Human cells are microscopic, but they vary in exact size

SHAPE - Most are cuboidal or spherical.◦ The size is limited by ratio between

surface area and volume. Supplies to support the volume must be able to enter and exit through the surface area of the cell membrane

CELL DIVERSITY

Cytoplasm Nucleus Cell Wall Mitochondria Cell Membrane

Important Organelles

Tissues

Tissues differ from each other in size, shape and the kind of material between their cells

FOUR MAIN TYPES OF TISSUES1. Epithelial - covers/lines body2. Connective - most abundant - connects body part3. Muscle - responsible for movement4. Nervous - responsible for sending quick messages

BODY TISSUES

Packed closely together Little or no intracellular material (matrix) Form continuous sheets, contain no blood

vessels

Epithelial Tissue

Squamous – flat and scalelike Cuboidal – cube shaped Columnar – higher than they are wide

Shape of Cells

Simple – single layer of cells of the same shape Stratified – many layers of cells of the same

shape Transitional – several layers of cells of different

shape

Arrangement of Cells

FORM:◦ Flat and scale-

like◦ Thin, irregular

shape FUNCTION:

◦ Absorption◦ Substances can

readily pass through

Ex: Oxygen absorbed into blood from lungs

Simple Squamous

FORM:◦ Several layers of

closely packed, scale-like cells

FUNCTION:◦ Protection

Ex: SKIN - protects against microorganisms◦ Microbes can’t go

through this type of tissue

Stratified Squamous

FORM:◦Single layer of cells

that are higher than wide

FUNCTION:◦Absorption

Make up lining of stomach, intestines, some of respiratory and reproductive tract

Simple Columnar

FORM:◦About 10 layers of

cuboidal, a few layers of squamous

FUNCTION:◦Ability to stretch,

withstand stress Ex: Found in wall or

urinary bladder, keeps bladder from tearing

Stratified Transitional

FORM:◦ About 2 layers

thick◦ Have cilia to

move mucous FUNCTION:

◦ Protects lungs against dust, etc

Ex: Lining of trachea

Pseudo-Stratified

FORM:◦ Single layer of cube

shaped cells FUNCTION:

◦ Allow for secretions Ex: saliva, digestive

juices, sweat, hormones

Simple Cuboidal

Most abundant and widely distributed Many different forms

◦ Found in skin, membranes, muscles, bones, nerves, and all internal organs

Connective Tissue

FORM:◦ Delicate webs of fibers

and cells in a loose matrix of soft, sticky gel

FUNCTION:◦ “glue” that gives the

form to internal organs◦ Provides strength,

elasticity and support Most widely distributed

◦ Found around blood vessels, nerves, organs; in mucus membrane; subcutaneous layer

Areolar

FORM: ◦ Large storage cells

FUNCTION:◦ Stores lipids (fats), insulation,

protection, energy reserve, generates heat in newborns

Found around organs, in yellow marrow, in subcutaneous layer

Adipose

FORM:◦ Bundles of strong,

white collagen fibers(for flexibility) in parallel rows

FUNCTION:◦ Flexible and strong

connections Makes up tendons,

ligaments, scar tissue

Dense Fibrous

FORM:◦ Matrix is hard and calcified◦ Made up of bone cells called

osteocytes FUNCTION:

◦ Support, protection, storage for calcium

Bone

Different from bone because:◦ Matrix is gel-like or like firm plastic◦ Breaks down over time◦ Fibers are invisible at regular magnification

Cartilage

Blood has a liquid matrix◦ Most unusual connective tissue

Blood

3 Kinds:◦ Skeletal, cardiac, smooth

Movement specialists of body Ability to shorten or contract Slow to heal

◦ If injured – usually replaced by scar tissue

Muscle Tissue

Also known as striated or voluntary◦ Voluntary muscle contractions possible

FORM:◦ Individual cells known as FIBERS ◦ Long and threadlike◦ Contain many nuclei per cell

FUNCTION:◦ Control body movements and move bones

Attached to bones

Skeletal Muscle

FORM:◦ Branched, lightly

striated, irregular shaped fibers

FUNCTION:◦ Regular, involuntary

contractions of heart to pump blood

FOUND: the heart muscle

Cardiac

Also known as involuntary◦ Not under conscious control

FORM:◦ Long, narrow fibers◦ No cross striations◦ Only one nucleus per fiber

FUNCTION:◦ Contraction of digestive tract, bronchioles in

lungs; changes diameter of blood vessels, pupils, shape of lenses

FOUND in the walls of blood vessels and hollow organs such as digestive system, respiratory system, urinary system etc

Smooth Muscle

FORM (2 kinds): ◦ Neurons – nerve cells

Cell body made up of one axon (transmits impulses away from body) and one or more dendrites (carry impulses towards body)

◦ Glial cells – connecting and supporting cells

FUNCTION:◦ Rapid communication

between body structures and control of body functions

Makes up brain, spinal cord and nerves

Nervous Tissue