Unit 10 Chapter 34 Protection, Support, and Locomotion

Functions of Skin? Sensory. Is it important that all skin is equally sensitive? Partner up. One will be the subject, one is the experimenter. The subject’s eyes should be closed during the testing. The experimenter touches the palm of the subject’s hand with a marker. The subject should then try to touch the exact point with his/her own marker (different color) with eyes still closed. Next, forearm, then fingertip. Measure the error of localization in millimeters. Record on board. Which areas have the most sensory receptors? Why?

Skin: the Body’s Protection Integumentary System Contains skin and its related parts— hair, nails & glands Four tissue types: Epithelial – covers the surface of the body Connective – tough and flexible protein fibers, acts like an organic glue Muscle – Interacts with hairs to respond to stimuli Nervous – Allows us to detect external stimuli (pain, pressure etc)

Skin: the Body’s Protection Layers within layers Two principle layers, each with unique structure and function Epidermis – has its own layers! Dermis

Epidermis: Outer layer of skin Exterior portion: layers of dead flattened cells Contains keratin: protects and gives elasticity Interior portion: Living cells that replace the dead cells Some contain Melanin, a pigment that colors the skin & protects cell from damage by radiation Takes about 28 days Epidermal ridges for grip.

Dermis: Inner Layer of Skin Thicker than the Epidermis Contains blood vessels, nerves, nerve endings, hair follicles, sweat gland and oil glands Oil glands Prevent hair from drying out. Keeps skin soft. Inhibits bacterial growth

Dermis: Inner Layer of Skin Hair follicles Narrow cavities out of which hair growth Have blood vessels, muscle and oil glands associated with them Sweat Glands Average human loses 900 mL of sweat/day!

Skin: the Body’s Protection Hypodermis (subcutaneous layer) Below the dermis Contains primarily of fat for cushioning & insulation, retaining heat and storing food.

Skin: Functions Regulates body temperature (part of homeostasis) Sweat is released in response to elevated body temperature As sweat evaporates, the body cools. Functions as a sense organ Nerve cells receive stimuli from outside and relay information on the inside. Produces vitamins – Vitamin D when exposed to light Helps the blood absorb Calcium Protects underlying tissues From physical & chemical damage and microbe invasion

Skin Injury and Healing Repair Stages (in response to injury) Blood flows to the wound until a clot forms Scab develops (barrier between bacteria and underlying tissues) New skin cells repair the wound from beneath

Bones: the Body’s Support Adult skeleton contains approximately 206 bones

Skeletal System Structure Two Divisions: Axial skeleton Includes the skull, vertebrae, ribs & sternum Appendicular skeleton Includes bones of the arms & legs, and shoulder & hip bones

Joints: where bones meet Joints Where two or more bones meet Usually facilitate the movement of bones in relation to one another Ends of moveable bones covered with cartilage for smooth movement.

Joints: where bones meet Joint Types Ball and Socket- hip, shoulder. Pivot – twisting, arm, head Hinge – elbow, knee, fingers, toes Gliding – wrists and ankles

Bones: the Body’s Support Ligaments Connective tissue that attaches one bone to another Tendons Connective tissue that attach muscles to bones

Two types of bone tissue Compact bone – layer of hard bone that surrounds every bone. Composed of osteon/Haversian systems Circular areas containing blood vessels, nerves and mature cells called osteocytes.

Two types of bone tissue Spongy bone Less dense bone filled with holes and spaces.

Formation of Bone In embryo, the vertebrate skeleton is made of cartilage By week 9, bone begins to replace the cartilage

Formation of Bone Blood vessels penetrate the cartilage and the cells become osteoblasts (potential bone cells) Osteoblasts secrete collagen (a protein) and causing minerals to be deposited. Calcium salts and ions harden, trapping the osteoblasts and they become osteocytes.

Bone Growth Growth in Length: Occurs at the ends of bones in cartilage plates Growth in Diameter (thickness) Occurs at the outer surface of the bone Accelerated by sex hormones during puberty

Skeletal System Functions Provides framework for the tissues in our body Protects internal organs Produces blood cells Red marrow- produces RBCs, WBCs and clotting agents (platelets) Yellow marrow – stores fat Stores minerals, including calcium and phosphates. Needed for strong, healthy bones, important part of diet.

Bone Injury and Disease Osteoporosis Loss of bone volume and mineral content. Bones become more porous and brittle with age. Broken bones Shown by X-ray images. Bones are moved back into position and immobilized for regrowth.

Muscles for Locomotion

Three types of Muscles

Muscles for Locomotion Smooth muscle Involuntary movement Found in hollow body organs, i.e. digestive tract, blood vessels Spindle-shaped cells, non-striated, one nucleus per cell

Muscles for Locomotion Cardiac muscle Involuntary movement Found only in the heart Interconnected to form a network for efficiency Generate and conduct electrical impulses Branching, striated (striped) cells, with one nucleus per cell

Muscles for Locomotion Skeletal muscle Voluntary movement Attach to and move bones, i.e. biceps, triceps, hamstrings, etc Long, striated (striped) cells, with many nuclei

Skeletal Muscle The majority of skeletal muscles work in opposing pairs. (i.e. flexor and extensor)

Muscles for Locomotion Common Skeletal muscles

Skeletal Muscle Contraction Muscle tissue is made up of muscle fibers (long fused cells): Muscle fibers (cells) are made up of smaller units called myofibrils.

Skeletal Muscle Contraction Myofibrils are composed of thick and thin filaments. Thick filament – myosin Thin filament – actin Each myofibril can be divided into sections called sarcomeres – functional unit of muscle.

Skeletal Muscle Contraction Muscle contraction: Sarcomeres contract (shorten) as the filaments, myosin & actin, slide toward one another. Sliding filament theory – best explanation, current model. link

Exercise The number of muscle cells are fixed at the time of birth. Working out makes you stronger, but you don’t get more muscle Muscle fibers increase in diameter in response to regular exercise. Muscle contraction requires ATP. How do we get ATP? Produced during cellular respiration in mitochondria!

Exercise During exercise, muscles use oxygen (aerobic respiration) This eventually shifts to anaerobic respiration and lactic acid is produced (fermentation). Lactic acid builds up. As you catch your breath, more oxygen is delivered and lactic acid is broken down. Regular exercise results in improved performance of muscles.