Anatomy & Physiology

Cells, Tissues, and Membranes

CELLS

A cell is microscopic in size.The cell is the basic unit of a

structure and function of all living things.

Special units are used when describing the size of cells, μm = micrometer and μ = micron.

Cells are classified by size and shape.They contain a cytoplasm which is a

living matter.Each cell is surrounded by a thin

membrane called the plasma membrane.Organelles are specialized structures and

are found in the cytoplasm of each cell.

Cell Membrane

Every cell is surrounded by a cell membrane, aka: plasma membrane.

Cell membrane separates the cell from it’s external environment.

Regulates the passage or transport of molecules in and out of the cell. Like a door watchman who allows people to enter or leave a private building.

It has a selective semi-permeable membrane, only lets certain things in or out of the cell.

Composed of lipids (steroids)Arranged in a double layer, like a

double set of entry doors.

Nucleus

It is the most important organelle within the cell.

It contains both DNA and RNA.Nucleus controls the cell function

(like an operator or director).Facilitates cell division, (46

chromosomes) in order for the cells to reproduce.

Nuclear Membrane

Is a double-layered membrane that has openings at regular intervals.

Through these ports, materials can pass from either the nucleus to the cytoplasm or from the cytoplasm to the nucleus. It works similar to valves by opening one section at time.

Cytoplasm

Sticky-semifluid material located between the nucleus and cell membrane. Has proteins, lipids, carbohydrates,

minerals, salts, and water.Background area for all chemical

reactions taking place in each cell.Organelles are within the cytoplasm and

they help the cell function.

Centrosome and Centrioles

Centrioles are 2 cylindrical organelles found near the nucleus in a small round, ribbed body called a centrosome.(looks like a pasta noodle)

During mitosis (cell reproduction), the centrioles separate to make 2 identical cells.

Endoplasmic Reticulum

Is a thin network of tubes that are inside the cell connecting the nuclear membrane to the cell membrane.

The network acts as a passageway or road for materials to travel in and out of the cell.

It can also store large amounts of protein for the cell.

Rough Endoplasmic Reticulum

Has ribosomes on it’s outer surface and this is where protein synthesis takes place.

Smooth Endoplasmic Reticulum

Is the site of cholesterol synthesis, fat metabolism, and detoxification of drugs.

Mitochondria

Supply energy to the cell.“Powerhouse” or PGE of the cell.

Golgi Apparatus

Synthesizes (breakdown) carbohydrates and combines them with the protein molecules as they are passing through the Golgi Apparatus.

The Golgi stores this products and packages it up to be discharged from the cell.(stores the trash or waste of the cell).

Lysosomes

Are oval shaped and found in the cytoplasm of the cell.

Help to digest protein molecules, old and worn out cells, bacteria, and foreign matter.

AKA as the suicide bags, if they rupture, they will cause the cell to die.

Perioxisomes

Sac that contains oxidase enzymes and they help to digest (breakdown) fats and neutralize harmful substances.

Cytoskeleton

Helps support the cell and aidsin movement.

Cell Division: Mitosis

Mitosis is the act of the cell reproducing itself.

It makes an exact duplicate of the first cell.

Our body does this to maintain a healthy system or environment.

Cells die or are destroyed by bacteria or tumors so we need to be able to make new ones to keep us alive.

Diagram of cell mitosisor cell reproduction.

Protein Synthesis

Cells produce proteins which are essential to life.

Depending on the type of cell it is, the amount and kind of protein may be different.

The DNA determines what kind of proteins the cell will produce.

Movement of Materials Across the Cell Membrane

The membrane controls what goes into and out of the cell. Much like a gatekeeper. Active transport means that the action

requires energy in order for it to take place.

Passive transport means that no energy is needed to move substances in and out of the cells.

Permeable Membrane

This is a membrane that only allows certain material to pass in and out based on it’s size.

Think of it like a strainer that you use when draining noodles. Only the water is released, not the noodles. Or a screen on a door. It lets the air through but keeps bugs out.

Phagocytosis

Act of cell eating.Here in this picture you can see the cell change shape as itsurrounds the green bacteria.Once it has surrounded the invader, the cell eats the bacteria away.

Regeneration

Cells regenerate at different times. Constant production:

Blood, Skin, and cells of the intestinal tract.

Every few years:Muscles

NEVER:Neurons or nerve cells or cells that have received

heavy damage such as heart cells during a heart attack. The cells turn black and die and do not regrow so the damage is permanent.

Disorders of Cells

Increase in size = hypertrophyDecrease in size = atrophyIncrease in number = hyperplasiaChange into another type of cell =

metaplasiaChange size, shape, and organization

= dysplasia

Sickle-cell

Cell injury

Basal cell carcinoma

lymphoma

Breast ca cell

AbnormalProstate cell

Dysplasia can lead to neoplasia which is an abnormal growth and cell structure change.

Neoplasia can change to cancerous cells.

mouth kidney Left lung

Trauma or injury to cells

Hypoxia = not enough blood flow to the cell structures

Anoxia = not enough or no oxygen to the cell will cause death

Bacterial or viral infections can also cause death to the cells

Tumors

Commonly known as neoplasms2 groups

BenignCells are confined to a local areaMost can be surgically removed

MalignantCancerousContinues to grow, interferes with other body

functions• If it spreads to another area in the body, it has

metastasized.

TISSUES and MEMBRANES

Cells that are grouped together are called tissues.

There are 4 main types of tissues. Epithelial Connective Muscle Nervous

Epithelial tissue

Protects the body by covering internal and external surfaces.

Can also produce secretions.Regulate passage of materials across

themselves.Form a continuous layer to cover

surfaces.

Epithelial

Can be stratified ( layered)

ciliated (hair-like)

keratinized (hard, nonliving)

Squamous epithelial cells

Flat, irregular shaped cells.Line the heart, blood & lymph vessels, body cavities, and the air sacs (alveoli) in the lungs.

Cuboidal epithelial cells

Cube-shaped cells that line the kidney tubules, cover the ovaries,And secretory parts of certain glands.

Columnar epithelial cells

Elongated cells that usually have the nucleus towards the bottomand are often called ciliated on the surface. They line the ducts, digestive tract, parts of the respiratory tract, and glands.

Epithelial

Glandular or secretory tissue

Specialized cells that secrete materials like digestive juices, milk,hormones, perspiration, and wax.Endocrine – form ductless glands that secrete hormones.Exocrine – cells secrete substances into ducts like sweat glands.

Connective Tissue

These are cells that support and connect organs and tissues of the body (matrix).

Found in bones, cartilage, mucous membranes, muscles, nerves, skin, and all internal organs.

6 classifications of connective tissue

Connective Tissue

1: Adipose tissue

It stores lipid (fat), acts as a filler tissue, cushions, supports, andinsulates the body.Loose type of connective tissue that has saclike cells for fatstorage. Found throughout the body, subcutaneous layer of theskin, around the kidneys, within padding around the joints, and In the marrow of long bones.

2: Areolar tissue

Surrounds various organs, temporarily stores glucose, salts, andwater. Supports nerve cells and blood vessels.Large semi-fluid matrix with cells and fibers embedded in it.The fibers are white fibrous protein called elastin and collagen.Found in the epidermis of the skin and subcutaneous layer withthe adipose cells.

3:Dense fibrous tissue

Forms ligaments, tendons, and aponeurosis.Ligaments hold bones together firmly at the joints.Tendons attach skeletal muscles to the bones.Aponeurosis holds one muscle to another or to the periosteum.Fascia wraps around muscles to hold them in place.Tissue is flexible, but not elastic and heals slowly.

4: Supportive tissue Osseous (bone) tissue

This type of tissue comprises the skeleton of the body and supportsand protects the soft tissue organs. It also helps with the attachmentof skeletal muscles.Osseous tissue’s matrix is calcified which gives the bones strength.

Cartilage, provides firm but flexible supportfor the embryonic and part of the adult skeleton.Hyaline cartilage forms the skeleton of the

growing embryo.Fibrocartilage is found between bones and

wherever great strength is needed. It is a strong, flexible and supportive substance.

Elastic cartilage has elastic fibers embedded throughout it’s matrix and this makes it firm but flexible.

• Found in the auditory ear tube, external ear, epiglottis, and larynx

Vascular (liquid blood tissue) tissueBlood transports food and oxygen to the

cells and carries waste products away from the cells. Contains specialized cells that aid in the body’s defense against invaders and also has a clotting factor in it.

Lymph system aids in the transportation of proteins, fats, tissue fluid, and other materials from the circulatory system through the lymphatic vessels.

5: Muscle 3 types

Cardiac Muscle helps the heart contract to pump blood through it. Found only in the heart. These muscles are involuntary.

Skeletal muscles are attached to the moveable parts of the skeleton and aid in movement. They are considered voluntary as we have conscious control over them.

Smooth muscles provide involuntary movement and aid in the movement of materials throughout the body. Such as walking contracts our muscles and helps move the lymph fluid through our body. It lines the walls of the digestive tract, blood vessels, genitourinary tract, and lymphatic system.

6: Nerve tissue Has the ability to react to stimuli.

Irritability = ability of a nerve tissue to respond to environmental changes.

Conductivity = the ability of the nerve tissue to carry the message (impulse) away.

MEMBRANES

Are 2 thin layers of tissue that are together and can secrete fluids.

Classified as epithelial or connective membranes.

Epithelial Membrane Can be mucous or serous

Mucous membranes line the interior surfaces that lead to the outside environment.

It produces mucus to protect and lubricate the lining.Respiratory, Gastric, and Intestinal Mucosa

Serous membraneDouble-walled membraneProduces a watery fluid called serous fluid

• Allows the organ to move without friction

Outer part that lines the cavity = parietal membrane

Cover the organ within = visceral membrane

• Pleural, Pericardial, and Peritoneal membrane

Connective membranes Consist of 2 layers of tissue

Synovial membrane• Prevents friction in a joint cavity