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.