Anaphy - Unit 3

Biological organization

• Molecules -> Cells: Molecules (like carbohydrates, lipids, proteins, nucleic acids) combine to form cellular structures.

• Cells -> Tissues: Cells with similar shape and function combine to form tissues. A key theme is that cell shape relates to cell function.

• Tissues -> Organs: Organs are clusters of different tissues specialized for particular functions (e.g., the heart contains all four tissue types).

• Organs -> Organ Systems: Organ systems are groups of organs with related functions (e.g., digestive system).

The Four Types of Human Tissues

1. Epithelial Tissue

2. Muscle Tissue

3. Nervous Tissue

4. Connective Tissue

Epithelial Tissue

Covers and protects surfaces (internal or external). Cells are often stacked in layers, appearing cuboidal or columnar.

Example: Skin (outer covering), lining of the mouth, lining of the stomach, lining of blood vessels.

Muscle Tissue

Cells contract (pull, never push) to cause movement. Muscles work in antagonistic pairs.

Example: Skeletal, smooth, and cardiac muscle

Skeletal Muscle

Striated (vertical stripes/bands). Controls the movement of the skeleton. Fast and strong, but tires/fatigues

Examples: Muscles attached to bones (e.g., biceps, triceps).

Smooth Muscle

Non-striated (no stripes). Found in internal organs. Not fast or strong, but has high endurance (never gets tired).

Example: Walls of the stomach, esophagus, and pharynx.

Cardiac Muscle

Found only in the heart. Has properties of both skeletal (fast/strong) and smooth (high endurance).

Example: Heart walls

Nervous Tissue

Made of nerve cells (neurons). Responsible for sending electrical signals/impulses (messages) throughout the body.

Example: Brain, spinal cord, nerves.

Connective Tissue

Supports, interlinks, and transports.

Example: Bone, cartilage, ligaments, blood (interconnects all body parts), and fat tissue (insulation, shock absorption, holds organs in place).

The Danger of Air in the Bloodstream

Blood is considered a connective tissue that transports nutrients and interconnects the body.

• The blood system operates on principles of hydraulics (continuous fluid flow).

• Introducing a gap, such as a large air bubble, disrupts this flow because liquids are incompressible, but gas is compressible.

• The force required to push the blood hits the air bubble, which compresses and absorbs the force without transferring it to the liquid beyond the gap, effectively stopping blood movement.

Digestion

Digestion is the process of breaking down food, absorbing nutrients, and eliminating waste.

Four stages of Digestion

Ingesting (eating), Digesting (breaking down), Absorbing (nutrients), and Eliminating (pooping/defecation; distinct from peeing/excretion)

Mechanical Digestion

A physical change that breaks food into smaller pieces. This includes mastication (chewing) using teeth and tongue, and the churning action of smooth muscle in the stomach walls.

Chemical Digestion

Changing the chemistry of the material (e.g., starches to glucose, proteins to amino acids). This process requires the aid of enzymes

Taste

Taste buds are spread around the entire tongue, correcting the previously mistaken idea that specific areas (like the tip) taste only one sensation (like sweet).