Lesson 2 - Support and Structure

Muscle

A tissue that supports the body and enables movement, made up of strong muscle tissues that can contract and relax.

Types of Muscles

Cardiac muscle

Muscle found in the heart, responsible for involuntary contractions.

Skeletal muscle

Muscle attached to bones, responsible for voluntary movements.

Smooth muscle

Muscle found in blood vessels and organs, responsible for involuntary movements.

Muscle Contraction

The shortening and thickening of a muscle.

Muscle Relaxation

The lengthening and thinning of a muscle.

ATP

Adenosine triphosphate, a molecule that stores energy and is produced in the mitochondria of muscle cells.

Joints

Places where two or more bones meet, providing flexibility and movement.

Ligaments

Tissues that connect bones to other bones, keeping them in place during joint movement.

Types of Movable Joints:

Ball and socket joint

Allows bones to move and rotate in nearly all directions (e.g., hips and shoulders).

Hinge joint

Allows bones to move back and forth in a single direction (e.g., elbows and knees).

Pivot joint

Allows bones to turn (e.g., neck and wrist).

Types of Joints:

Hinge joint

Moves in only one direction (e.g., knees, elbows, fingers).

Pivot joint

Rotates (e.g., neck, wrist).

Ball and socket joint

Moves in all directions (e.g., hips, shoulders).

Immovable joints

Joints where two or more bones are in close contact but no movement can occur (e.g., bones of the skull).

Skeletal System

The system mainly made up of bones that provides support and structure to the body, protects organs, helps in movement, produces red blood cells, and stores calcium and fats.

Types of Skeletons:

Hydrostatic skeleton

A fluid-filled internal cavity surrounded by muscle tissues.

Exoskeleton

A thick, hard outer covering that protects animals.

Plant Support Systems:

Roots

Anchor the plant and help it stay upright.

Stems

Support branches and leaves, transport water, minerals, and food, and produce new cells for growth.

Types of Stems:

Woody stems

Stiff and not green.

Herbaceous stems

Soft and green.

Types of Roots:

Taproot

A large main root with smaller roots growing around it.

Prop root

Small roots above ground for support.

Fibrous roots

Consist of many small branching roots.