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INTRODUCTION TO BODY
STRUCTURE
BODY ORGANIZATION1. The levels of organization of the body:
cells- individual unit
tissues- Similar cells that work together to perform a common function.
organs- Combination of 2 or more tissues that work together to perform a common function
organ system- Group of organs that work together to perform a specific function.
BODY ORGANIZATION
Maintaining homeostasis requires:
1. Body’s organs functioning together.
2. Temperature regulation (endotherms)
3. Adjusting metabolism
4. Detecting and responding to stimuli
5. Maintaining water and mineral balances
IntegumentarySystem
Consists of:Skin, Hair, &
Nails
Skin
The largest organ in your body. Yes, skin is an organ.
Functions of the Skin Protective barrier against pathogens Prevents water loss Offers body protection Regulates body temperature through sweating
Four Tissues of the Integumentary System
•Epithelial- covers body surfaces•Connective- provides support and protection•Muscle – body movement•Nerve- forms body’s communication network
3 layers of skin
1. Epidermis: Top layer Constantly makes new skin cells to replace dead
ones Contains keratin, which as a waterproof barrier Also contains melanin, a brown pigment that
helps protect you from UV rays. (This is why people tan)
3 layers of skin
2. Dermis: The 2nd layer of skin Contains hair follicles (each follicle contains 1
hair) Contains the sebaceous glands which produce
an oil called sebum. This lubricates the skin and hair.
Contains sweat glands. These release water and some wastes to cool the body and maintain homeostasis
3 layers of skin
3. Subcutaneous tissue: The 3rd layer Composed of fat cells This is used for insulation and an energy supply
SKIN LAYER DIAGRAM
HAIR FOLLICLESWEAT GLAND
SEBACEOUS
GLAND
EPIDERMIS
DERMIS
SUBCUTANEOUS
TISSUE
SKELETAL SYSTEM
Functions of the skeleton:
1. Support the body
2. Provide protection for the internal organs
3. Enables movement
SKELETAL SYSTEMThere are 206 bones in the skeleton.
The skeleton is divided into 2 parts:
1. axial- includes the skull, spine, ribs, and sternum
2. appendicular- includes shoulders, arms,
hips, and legs
SKELETAL SYSTEM
Bone is made of hard compact bone
surrounding porous bone.
BONE MARROW RED – makes all blood cells for body (RBC,
WBC, & platelets)
YELLOW = stores fat tissue
SKELETAL SYSTEMEarly in development, the skeleton is made mostly
of hyaline cartilage.
Bones hardens as calcium, phosphate and other mineral deposits build up.
Osteoblasts make bone tissue.
Bones thicken and elongate as development continues.
SKELETAL SYSTEMJOINT = where 2 bones meet.Three types of joints:1. Immovable
permits little or no movement.ex. skull joined by sutures.
2. Slightly moveableex. Spine and ribs
3. Freely moveable joints (see table 2 p. 854)
ex. knee
SKELETAL SYSTEM
1. Ligament: Connects bone to bone
2. Tendon: Connects muscle to bone
Osteogenesis Imperfecta
MUSCULAR SYSTEM
Functions Include: Movement in body Generate Heat for Body Temperature
MUSCLES Involuntary muscles – not under conscious control.
1. Smooth muscles – line internal organs & blood vessels.
a. Function of smooth muscle is to contract. b. Smooth muscle contractions are slow.
MUSCLE
2. Cardiac muscle – heart muscle.
Adapted to conduct electrical
impulse.
MUSCLEVoluntary muscles – under conscious control skeletal system.
3. Skeletal muscles – attached
to the bones & skeletal system.
a. Majority of muscles are skeletal b. Contractions are short & strong
MUSCLEPage skeletal muscle structure
1. Skeletal muscle are made up of bundles of muscle fibers.
2. Each muscle fiber is made up of myofibrils.
MUSCLE
3. Myofibrils are made up of smaller
proteins filaments.
a. Myofibrils are striated or divided
into sections called sarcomeres
which are the functional units of the
muscle
MUSCLE
4. Two types of filaments
a. Thick filaments are made up
myosin.
b. Thin filaments are made up of
actin.
MUSCLES
Sliding Filament Theory
1. during contractions, actin filaments
move towards one another from the pulls of myosin heads
Muscular Dystrophy
NERVOUS
The function of the nervous system is allow an organism to think, learn, perceive, move, and express emotion.
Neurons are specialized cells that transmit information thought the body by conducting
electrical signals called nerve impulses.
NERVOUSStructure of Neurons: (see p. 944)1. Dendrites – receive information from other cells.2. Cell body – collects information from the
dendrites, relays the information, and maintains the neuron.3. Axon – conducts nerve impulses.4. Axon terminals – Where neuron communicate
with other cells. 5. Nerves- bundles of axons
NERVOUSMyelin sheath is a layer ofinsulation foundon some neurons.
Myelin sheaths causes nerveimpulses totravel faster down the axon.
Nodes of Ranvier – gaps betweenthe myelin sheath.
NERVOUS - see p. 948
Synapse – where a neuron meets another
cell.
Neurotransmitters – a chemical that transmits
the electrical impulse across the synapse.
NERVOUS
The central nervous system consists of the brain and spinal cord controls the body responds to stimuli from the environment
NERVOUS
Peripheral nervous system contains:
Sensory neurons – send information from sense organs to the CNS.
Motor neurons – send commands from the CNS to muscles and other organs.