INTRODUCTION TO BODY STRUCTURE BODY ORGANIZATION 1 The

INTRODUCTION TO BODY STRUCTURE

BODY ORGANIZATION 1. 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 2. List the 4 types of body tissues: epithelial- line the body surfaces. nervous- nerve cells connective- fat, cartilage, bone, and tendon muscle- smooth, skeletal and cardiac

BODY ORGANIZATION n ORGANS AND ORGAN SYSTEMS See table 1 on page 848

BODY ORGANIZATION Maintaining homeostasis requires: 1. 2. 3. 4. 5. Body’s organs functioning together. Temperature regulation (endotherms) Adjusting metabolism Detecting and responding to stimuli Maintaining water and mineral balances

SKELETAL SYSTEM Functions of the skeleton: 1. 2. 3. Support the body Provide protection for the internal organs Enables movement

SKELETAL SYSTEM There 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.

SKELETAL SYSTEM Early in development, the skeleton is made mostly of cartilage. Bones hardens as calcium and other mineral deposits build up. Bones thicken and elongate as development continues.

SKELETAL SYSTEM Three types of joints: 1. Immovable permits little or no movement. ex. skull joined by sutures. 2. Slightly moveable ex. Spine and ribs 3. Freely moveable joints (see table 2 p. 854) ex. knee

SKELETAL SYSTEM 1. Ligament: a type of tissue that holds together the bones in a joint. 2. Tendon: a tough connective tissue that attaches a muscle to a bone or to another body part.

MUSCLE 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.

MUSCLE Voluntary 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

MUSCLE Page 857 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 (myosin filaments do not move)

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.

NERVOUS Structure 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

NERVOUS Myelin sheath is a layer of insulation found on some neurons. Myelin sheaths causes nerve impulses to travel faster down the axon. Nodes of Ranvier – gaps between the 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 n consists of the brain and spinal cord n controls the body n responds to stimuli from the environment

NERVOUS Peripheral nervous system contains: Sensory neurons – send information from sense organs to the CNS. n Motor neurons – send commands from the CNS to muscles and other organs. n