1. Cell is the lowest level that can live as an organism.
2. Tissues (weave) groups of cells with a common structure and function. Tissues are held together by an extracellular matrix.

1. Human Tissues

1. Epithelial
2. Connective
3. Muscular
4. Nervous

1. Organs have several types of tissues

1. Organs are grouped into organ systems, which have specialized functions.
2. Organs help maintain constant conditions in the internal environment (homeostasis).
3. All organ systems contribute to homeostasis.

1. Epithelial Tissue

1. Characterized by having a free surface, which is exposed to air, and having a basement membrane at the base on which sequential events in cell metabolism can be organized.
2. Tightly Packed cells forming a continuous sheet over the entire body surface and the bodies inner cavities. On the outside it protects from injury and drying out and on the inside it secretes mucus, has cilia for sweeping, and cells for absorption of molecules from kidney via micorvilli. Microvilli can secrete or absorb chemicals.
3. Shapes

1. Squamous-flattened cells like flat floor tiles.
2. Cuboidal-cube shaped cells look like dice.
3. Columnar-resemble columns like bricks.

1. Layers

1. Simple- a single layer.
2. Stratified- piled on top of each other.
3. Pseudostratified- single layer with varying length of cells.
4. Layer(s) connected to basement membrane.
5. Basement membrane joins epithelium to connective tissue

1. Junctions join epithelial cells

1. Tight impermeable junction-liquid must go into and not around a cell.
2. Adhesion junction-in areas of stretch and stress.
3. Communication junction-for cells that must work together.

1. Glands

1. Can secrete a product
2. Glands can be single cells such as a mucus secreting goblet cell in the digestive tract, or many cells.
3. Exocrine secretes product into ducts.
4. Endocrine secretes product into blood.
5. Pancreas is an exocrine (digestive enzymes) and endocrine gland (Insulin).

1. Connective Tissue

1. Bind and support other tissues and is characterized by a space population of cells scattered in an extrcellular matrix.
2. Binds structures together, protection, stores fat, fills spaces, form blood cells. A matrix separates connective tissue cells.
3. A matrix is non-cellular material between cells.
4. Fibers

1. White-collagen
2. Yellow-elastin

1. Loose connective tissue: Adipose tissue is an example. Binds structures. Just below epithelial layers. Cells are far apart. Cells called fibroblasts.
2. Fibrous connective tissue: Tendons and ligaments. Collagenous fibers are close together. Tendons connect muscles to bones and ligaments connect bones to bones at joints. It takes these tissues a long time to heal because they have a low blood supply. Fibers are arranged in parallel bundles. Cells also called fibroblasts.
3. Cartilage: less rigid matrix, solid yet flexible. Cells lie in small chambers called lacunae, and are separated by a matrix. Rubbery matrix (chondroitin sulfate).

1. Hyaline- nose, long bones, ribs, supporting rings of the windpipe and fetal skeleton
2. Elastic-external ear, part of larynx,
3. Firbrocartilage-pads between vertebrae knee joint. Degrades as person ages.

1. Bone: Rigid Matrix(mineralized)

1. Most rigid connective tissue.
2. Hard matrix of calcium salts and protein fibers (like steel rods).
3. Compact bone (found in shaft)-a osteoblast is strapped in its secretions and becomes an osteocyte (bone cell). Bone cells are in lacunae.
4. Lacunae are in concentric circles around Haversian canals.
5. Nerve fibers and blood vessels are in the canals. Nutrients travel to bone cells via canaliculi.
6. Spongy bone has numerous bony bars and plates separated by irregular spaces. Spongy bone is lighter than compact bone.

1. Blood: liquid matrix called plasma

1. Cells are separated by plasma
2. Red blood cells (RBC) called erythrocytes. RBC carries oxygen.
3. White blood cells (WBC) called leukocytes. WBC fight infection
4. Platelets are involved in clotting. Platelets are cell fragments.
5. Plasma has ions and molecules.
6. You can bleed to death in one minute or less.
7. If you lose one quart of blood you go into shock and then die.

1. Muscular Tissue

1. Muscle fibers are cells made of muscular contractile tissue. Composed of actin and myosin filaments.
2. Types of muscle tissue

1. Skeletal-attached to bone via tendons. Moves body parts. Fastest contractor. Cylindrical and long, with multiple nuclei, striated. Light and dark bands due to actin and myosin placement. Under voluntary control.
2. Smooth-lack striations. Involuntary control. Found in intestine and stomach. Slower than skeletal muscle. Contracts intestine walls and moves food along digestive tract.
3. Cardiac-Wall of heart. Striated but under involuntary control. Only one nucleus. The cells are branched and fused at the ends. Bound at intercalated disks. The ends are folded and have desmosomes and gap junctions.

1. Nervous Tissue

1. Functions to sense stimuli and transmit signals.
2. The functional unit is a neuron.

1. Dendrite-conducts impulse towards cell body.
2. Cell body- has the nucleus.
3. Axon-conducts impulse away from cell body.

1. Nerve fibers are outside the brain and spinal cord. They are bound by connective fibers to make nerves.
2. Neuroglial cells support, protect and feed neurons.
3. An axon can be 1 Meter is length.
4. Brain shrinks as you age. In Alzheimer’s brain can shrink a lot.

1. Skin as an organ (Integumentary system)

1. Function

i. Protects from physical trauma, microbial invasion, water loss, regulates body temperature, and senses the environment.

2. Skin Layers

1. Epidermis is the outer layer. Stratified squamous epithelium. Produced by a bottom layer of cells called the basal cells. New cells push to the surface. Then they flatten and harden. This is due to a waterproof protein called keratin. Dandruff is keratinization 2,3 times the normal rate. Fingerprints and footprints are dead keratinized cells. Melanocytes produce melanin. This produces skin color. Melanin is more active in sun to protect the skin from UV light.
2. Dermis is thicker with elastic and collagen fibers. Age and sun decrease these fibers and the skin is less supple and prone to wrinkling. Location of hair shaft, hair follicle, and oil glands. A blackhead is oxidized sebum. Pus-inducing bacteria leads to a boil or pimple. Arrector pili muscle is attached to hair and when it is cold this muscle will straighten hair. Location of sweat glands. Location of receptors and blood vessels. Skin appears blue when cold, and turns red when you blush.
3. Subcutaneous Layer is loose connective tissue, adipose tissue, and insulation. Gives a rounded appearance. Attached to muscles.

1. Skin Cancer

1. Ozone depletion. O3 barrier is about 50Km in the atmosphere. Keeps UV light out. Less ozone means more UV light and more mutations in DNA, more cataracts, kills krill in ocean, and bad for the immune system.
2. 10 % decrease in ozone = 26 % increase in skin cancer/cataracts.
3. Gene patched is responsible for basal cell carcinoma.
4. Tanning is when melanocytes rise to surface to protect skin.
5. CL in atmosphere, CFC’s from Styrofoam, and air conditioners destroys ozone.
6. UV damage = sunburn and wrinkling of skin, and skin cancer.

1. Burns

1. 1st Degree: Epidermal layer, redness, pain and swelling. Skin peels off.
2. 2^nd Degree: Epidermis and Dermis. Pain and blistering.
3. 3^rd Degree: Not painful because nerve endings are destroyed. Infection is a problem. A graft or artificial skin (made from shark cartilage and collagen fibers from cowhide or silicone plastic) can be used to repair damage.

1. Homeostasis

1. Maintenance of constant internal conditions.
2. French physiologist Claude Bernard "maintain constant conditions in the internal environment".
3. Blood glucose concentration is at 0.1 %
4. pH of blood in 7.4
5. Blood pressure of brachial artery is 120/80
6. Body temperature is 37 degrees C.

10. Body cavities

11. Organ Systems