Skin: The Body s Protection

Transcription

1 Ch 34: Protection, Support and Locomotion Skin: The Body s Protection Inside This Section... The Structure of Skin The Function of Skin Response to Injury Structure and Function of the skin 4 tissue types in the body: - covers the surface of the body - tough and flexible protein fibers, acts like an organic glue - Interacts with hairs to respond to stimuli such as cold and fright - Allows us to detect external stimuli (pain, pressure etc

2 Structure and Function of the skin 2 layers: - Outer Layer - Inner Layer Epidermis: Outer layer portion layers of dead flattened cells Contains : protects and gives elasticity portion Living cells that replace the dead cells Some contain - colors the skin. Protects cells from damage Takes about 28 days than the Epidermis Thickness varied in different parts of the body Contains blood vessels,, nerve endings, hair follicles, sweat glands and oil glands. glands Dermis: Inner layer Prevents hair from drying out. Keeps skin soft. Inhibits growth

3 Dermis: Inner layer Hair follicles Narrow cavities out of which hair grows Glands Average human looses of sweat/day Regulates internal body Sweat is released in response to elevated body temperature As sweat evaporates, the body cools Functions as a organ cells receive stimuli from outside and relays information to the inside The Functions of the Skin Produces vitamins - when exposed to light. Helps the blood absorb Calcium Protects the underlying The Functions of the Skin

4 Skin Injury and Healing Repair stages (in response to injury): Blood flows to the wound until a forms develops (barrier between bacteria and underlying tissues New repair the wound from beneath The Structure of Skin The Function of Skin Response to Injury Ch 34: Protection, Support and Locomotion - Bones: The Body s Support In Review...

5 Inside This Section... The Structure of the Skeletal System The Formation of the Skeletal System The Function of the Skeletal System Bone injury and disease Skeletal System Structure The adult human skeleton contains approximately 206 bones 2 main parts: The Skeleton: The skull and the bones that support it (vertebral column, ribs, sternum) The Skeleton: Bones of the arms and legs and structures associated with them

6 What are Joints? Where two or more meet Usually facilitate of bones in relation to one another (not the joints of the skull) Held together and enclosed by : Tough band of connective tissue Two types of bone tissue bone: layer of hard bone that surrounds every bone Composed of osteon systems : living bone cells. Receive O2 and nutrients from small blood vessels within osteon system Nerves conduct impulses to and from each cell bone: less dense bone, filled with holes and spaces Formation of Bone In embryo, the vertebrate skeleton is made of By week 9, bone begins to replace the cartilage Blood vessels penetrate the cartilage and the cells become (potential bone cells) Week 7 Compact and Spongy Bone

7 Formation of Bone Osteoblasts secrete the protein Deposits (i.e. calcium) in the bloodstream Calcium salts and other ions cause the osteoblasts to harden and become Week 7 Growth in Length: Occurs at the ends of bones in Growth in Diameter (thickness) Occurs at the outer surface of the bone Accelerated by Sex during teen years. Bone injury and disease Loss of bone volume Bones become more porous and brittle Broken bones Shown by images Bones are moved back into position and so the bone can regrow Bone Growth

8 In Review... The Structure of the Skeletal System The Formation of the Skeletal System The Function of the Skeletal System Bone injury and disease Ch 34: Protection, Support and Locomotion Muscles for Locomotion Inside This Section... The 3 Types of Muscles How Muscles Work Muscles during Exercise

9 3 Types of Muscles muscle muscle muscle Found in the walls of internal (i.e. organs of the digestive tract) and blood Also called muscle (not under conscious control) Cardiac Muscle Found ONLY in the Interconnected to form a network to help muscle cells contract efficiently Adapted to generate and conduct electrical Source: Patrick J. Lynch, medical illustrator Smooth Muscle

10 Skeletal Muscle Attached to, and moves, Also called muscle (under conscious control) The majority of skeletal muscles work in opposing Muscle tissue is made up of muscle fibers (long fused muscle cells) Each fiber is made up of myofibrils (2 kinds): Thick filament ( ) Thin filament ( ) Appears (striped) Exercise The number of muscle cells are fixed at time of birth Working out makes you, but you don t get more muscle Muscle fibers increase in in response to regular exercise Muscle contraction required Skeletal Muscle

11 During exercise, muscles use oxygen ( respiration) This eventually shifts to anaerobic respiration and is produced Exercise Lactic acid builds up. As you catch your breath, more oxygen is delivered and lactic acid is broken down Regular exercise results in improved of muscles In Review... The 3 Types of Muscles How Muscles Work Muscles during Exercise