Cell Structure – More Detail

Cellular Biology: A Refresher

Anatomy and Physiology 121:

Dr. Jaeson T. Fournier

Cell Structure – More Detail

Compartmentalization

Compartmentalization is an important concept relative to the study of biology.

Biological activities typically occur in defined locales – i.e. separating one environment from another.

Examples of Body Compartments

Unique to Human?

Compartmentalization - Unique

Not unique to humans

Compartmentalization: Anatomical vs. Physiological Compartmentalization

Biological Exchange

Diffusion = the overall (net) movement of molecules from an area where they are more concentrate to an area where they are less concentrated.– Example: Drop of dye spreading throughout the

water cup

Biological Exchange

Why does diffusion occur?– All molecules in the universe are in constant

motion. – In gases (more widespread) molecules move

rapidly and unrestricted; in liquids it move more slowly because molecules are closer. It is slowest in solids, because molecules are the closest.

– Molecules move because of their own energy and as a result of being hit by other molecules.

Biological Exchange

Movement of Molecules– Is usually random and due to their own energy

or being hit by another molecule.– Diffusion though is not random, as molecules

also like to be in equilibrium and will move from an area of high concentration to an area of lower concentration.

Biological Exchange

Gradient = the difference in concentration of a substance from one area to another

Diffusion = net movement of a substance down its own concentration gradient

Biological Exchange

Biological Exchange

Differentially Permeable Barrier – A membrane that surrounds every cell– Membranes act as a selective barrier that

controls the movement of materials in an out of cells.

– This means that some molecules to enter a cell and others do not.

• Water, oxygen, carbon dioxide crosses easily.

• Large molecules do not and usually need assistance.

Biological Exchange

Osmosis = diffusion of water across differentially permeable membranes.

Biological Exchange

Diffusion is a slow process Any organism that is visible to the naked

eye (such as a human) relies on diffusion only.

Levels Of Structural Organization in the Human Body: Tissue = Group of cells with similar

structure and function.– 4 types of tissue in the human body

• Epithelial, Muscle, Connective, Nervous Tissue

Levels Of Structural Organization in the Human Body: Epithelial Tissue

– Covers external and internal body surfaces• Examples

– Skin; alimentary canal

• Function– Protect the body’s surfaces and produce secretions such as

sweat and mucus

Levels Of Structural Organization in the Human Body:

Levels Of Structural Organization in the Human Body: Connective Tissue

– Found throughout the entire body– Secretes nonliving material that forms a matrix

(which may be solid or liquid)• Examples

– Blood; Bone

• Function– Connects, supports and protects body structures

Levels Of Structural Organization in the Human Body:

Levels Of Structural Organization in the Human Body: Nerve Tissue

– Made up of nerve cells (neurons)• Examples

– Brain; spinal cord

• Function– Specialized to transmit an electrical signal from one part

of the body to another

Levels Of Structural Organization in the Human Body:

Levels Of Structural Organization in the Human Body: Muscle Tissue

– Consists of cells that are able to contract in response to stimulation (electrical)

• Examples:– Skeletal; Smooth and Cardiac – actually these are the

types of muscle tissue

• Function– Gives shape and support to the body and produces heat.

– Body motion (segmentally and as a whole)

Levels Of Structural Organization in the Human Body:

Levels Of Structural Organization in the Human Body: Organ

– Group of tissues organized together to form a structural and functional unit.

– Every organ consists of all 4 basic tissue types.– Examples

• Stomach, heart, kidney