Cells and tissues

Structure and function of cellsOrganization of cells into tissues

A “generalized” cellAll living things are made of cells

Major components of the cell

• Membrane• Nucleus• Cytoplasm

– Cytosol– Organelles

The plasma membrane controls the movement of materials into and out of cells

The nucleus

• Most cells have one nucleus

• Contains chromosomes (genetic material)

• Nucleolus• Nuclear pores control

movement across membrane

Components of the cytosol

• Cytosol– Fluid part of cell– Many ions, proteins, etc. dissolved in it– Many chemical reactions occur there

• Organelles– Specialized structures– Compartmentalized functions

Functions of organelles• Movement, support

– cytoskeleton• Protein synthesis

– Ribosomes, rough ER, Golgi

• Waste disposal– lysosomes

• Metabolism– mitochondria

• Genetic information– nucleus

• Transport– Plasma membrane

Cell division

• Reproduction, replacement• Some cells divide rapidly• Some cells divide slowly• Some cells divide abnormally

Specialized cells form tissues

• Epithelial tissue– One or more continuous sheets of cells– Tightly bound together

• Basement membranes are formed beneath epithelia

• Major functions– Covering or lining– Glandular

Types of epithelium

• Epithelium is categorized by shape and arrangement

• General functions: protection, secretion, absorption

Some types of epithelium

• Simple squamous– Lines blood vessels,

alveoli, etc.– Materials move

through it (diffusion, osmosis)

• Simple columnar– Lines intestines– Secretion and

absorption

More epithelium

• Stratified squamous– Skin, mouth,

esophagus, vagina– Protection

• Pseudostratified ciliated columnar– Upper respiratory tract– Cilia help move mucus

Connective tissue

• Protection• Insulation• Compartmentalization

• Component of body membranes– Cutaneous– Serous– Mucous– synovial

Types of connective tissue

• Loose• Dense• Cartilage• Bone• Blood and lymph

• See plates starting p. 63

Examples of connective tissue

Membranes

• Cutaneous– Covers the body– Keratinized cells

• Serous– Line peritoneal,

pleural, pericardial cavities

• Mucous– Line passageways

that connect to the exterior

• Synovial– At joints– Anti-inflammatory

function

Muscular tissue

• Skeletal, cardiac, smooth

• Voluntary or involuntary

• Location in body

• See table 3.4

Cardiac and smooth muscle

Nervous tissue

• Neurons • Glial cells• Conduct electrical

stimuli• Support neurons

Summary

• Living organisms are composed of one or more cells

• Cells are organized into tissues• Type and arrangement of cells (and

extracellular materials) are unique to the tissue

• Organs are formed from tissues that perform characteristic functions