Transcript Introduction To Body Structure

Introduction To Body Structure
Chapter 38
Body Organization
• 4 Kinds of body tissues
– Epithelial Tissue:
• Lines most body surfaces
• Protects other tissues from
dehydration and physical damage.
– Nervous Tissue:
• Consists of nerve cells and their
supporting cells.
– Connective Tissue:
• Support, protect, and insulate the
body.
– Ex. Fat, cartilage, bone, tendons, and
blood.
– Muscle Tissue:
• Enables the movement of body
structures by muscle contraction.
– 3 kinds of muscle tissues
» Skeletal Muscle
» Smooth Muscle
» Cardiac Muscle
Body’s Major Organ Systems
Skeletal System
• Skeleton has two main parts
– Axial Skeleton:
• The skull, spine, ribs and sternum
• The axis of the skeleton
– Appendicular Skeleton:
• Shoulder and arm bones, hip and leg
bones
• All the bones of the limbs
(appendages)
– Scapula, Clavicle, Humerus, Ulna,
Radius, Carpals, Phalanges
– Pelvis, Femur, Patella, Tibia, Fibula,
Tarsals, Phalanges
Structure of Bone
• Periosteum:
– Outer lining of bone
• Compact Bone:
– Hard dense bone
• Spongy Bone:
– Hard, holey bone
• Bone Marrow:
– Soft center where blood cells are produced
• Haversian Canal:
– Tubes which contain blood vessels and nerves
• Osteocytes:
– Living bone cells found in compact bone
Structure of Bone Cont.
Joints Fasten Bones Together
• Three main types of joints
– Immovable
– Slightly moveable
– Freely moveable
• Joint:
– A place where two or more bones meet.
• Cartilage:
– Covers the ends of bones at joints and provides a cushion
• Ligaments:
– Strong connective tissue that holds a bone to another bone,
while being flexible enough to allow movement
Muscular System
• Functions of the Muscular System
– Allow for voluntary movement
• Ex. Walking and Talking
– Allow for involuntary movement
• Ex. Blood flow, heart beat, and food digestion
• 3 Type of Muscle
– Smooth:
• Lines the walls of blood vessels and intestines
and is controlled unconsciously
– Cardiac:
• Found only in the heart and is controlled
unconsciously.
– Skeletal:
• Connected to bones and allows for voluntary
movement.
Muscle Contraction
• Muscles work in opposing
pairs.
– When one muscle
contracts, the other relaxes.
• Each muscle fiber is made of
small cylindrical structures
called
• Myofibrils:
• Segments that come together
are called
– Sarcomeres:
» Composed of 2 proteins
• Myosin:
• Thick protein
filaments
• Actin:
• Thin protein
filaments
Fiber
Steps of Muscle Contraction
1. Nerve impulse is sent to the muscle
2. Myosin attaches to actin
–
Need calcium
3. Myosin head rotates, causing actin to slide
past myosin.
4. ATP is used to detach myosin head from
actin.
–
It will then reset itself to normal position.
5. If calcium is still present, the myosin will
bind to actin again.
Muscle Contraction Cont.
• Sliding filament theory:
– When signaled, actin filaments slide toward one
another, shortening the sarcomere
Skin, Hair, and Nails
• Skin has 2 distinct layers
– Epidermis:
• Outer layer of skin
– Exterior layer
» Dead skin cells that contain keratin, which protect the living
skin underneath.
– Interior layer
» Living skins cells that continually die and replace the
exterior layer above.
• Contains melanin, which gives skin its color and helps
protect the body from solar radiation.
– Dermis:
• Thick layer of living skin. Contains blood vessels, hair follicles,
nerves, sweat and oil glands.
Skin, Hair, Nails Cont.
•
Hair - Provides protection and insulation
• Grow from bulb
• Dead cells (shaft) pushed out
• Serves to retain body heat
•
Nails – Provide protection
• Grow from nail bed (lunula)
• Fill with keratin (protein for hardening)
• Dead cells pushed out