Support & Movement Chapter 24

General Info…….. Skin has 2 layers Epidermis - outer layer Dermis – inner layer Has Sweat glands that excrete sweat through the pores. It is the body ’ s first line of defense! It is the largest organ of the body.

Epidermis Contains thin outer layer of dead skin cells called the cuticle. This is the layer that you see everyday. When you complain about being ” ashy ”, it is because this layer of dead skin cells is very rough and raggedy. Most of the “ dust ” you see around your house is made up of dead skin cells! Under the cuticle is another layer of living epithelial cells that make up the rest of the epidermis.

Skin Color Melanin is a pigment in the skin that is mostly responsible for skin color Tan= extra melanin Albinism

Protection Calluses protect your skin once they have formed What is a blister? What other ways does your skin protect you?

Homeostasis When you sweat, heat leaves the body through your pores. When the sweat hits the outer surface of the skin, it is cooled by the air. This lowers your body temperature. Also called perspiration

Parts of the Skeleton  Bones (skeleton)  Joints  Cartilages  Ligaments (bone to bone)  Tendon (bone to muscle)

Functions  Support of the body  Protection of soft organs  Storage of minerals and fats  Blood cell formation  Movement due to attached skeletal muscles

Bones  The skeleton has 206 bones  Two basic types of bone tissue  Compact bone  Homogeneous  Spongy bone  Small needle-like pieces of bone  Many open spaces

Figure 5.1 Classifications

 In embryos, the skeleton is primarily cartilage  During development, much of this cartilage is replaced by bone  Cartilage remains in isolated areas  Bridge of the nose  Parts of ribs  Joints Changes in the Skeleton

A hinge joint allows extension and retraction of an appendage. (Elbow, Knee) Joints

A ball and socket joint allows for radial movement in almost any direction. They are found in the hips and shoulders. (Hip, Shoulder) Joints

In a gliding or plane joint bones slide past each other. Mid-carpal and mid-tarsal joints are gliding joints. (Hands, Feet)

Joints In a pivoting joint the bones act as a hinge but can also pivot. (Arm)

Joints In a fused joint the bones are fused together and do not move at all. (Skull, sacrum)

The Muscular System

Did you know that ? -More than 50% of body weight is muscle ! -Muscle is made up of proteins and water

Info About Muscles Only body tissue able to contract Create movement by flexing and extending joints

Voluntary movement of skeletal parts Spans joints and attached to skeleton Skeletal Muscles

Found in walls of hollow internal organs Involuntary movement of internal organs Elongated, spindle shaped fibre with single nucleus Smooth Muscle

Cardiac Muscle Found only in the heart Striations Involuntary movement of the heart Usually has a single nucleus, but can have more than one

Cardiac muscle Main muscle of heart Pumping mass of heart Critical in humans Heart muscle cells behave as one unit Heart always contracts to it’s full extent

Muscle Control Type of muscle Nervous control Type of control Example Skeletal Controlled by CNS Voluntary Lifting a glass Cardiac Regulated by ANS Involuntary Heart beating Smooth Controlled by ANS Involuntary Peristalsis

Flexion

Extension

Hyperextension

Rotation