Muscular & Skeletal Systems

Muscular SystemMuscles are the motors that move body parts.

Bones and joints have no power to move on their own.

More than 600 muscles in the body– 35–40% of body mass

is muscle

Muscular SystemMuscle—organ that contracts and becomes shorter or expands and becomes longer– Result = Body parts move, energy is

used, and work is done.

Muscular SystemTwo Groups of Muscles1. Voluntary—You can control

these.Arms, legs, hands, face

2. Involuntary—You can’t control these; you don’t have to decide to make these muscles work.Muscles around the heart

Muscular SystemThree Types of Muscle Tissue

1. Skeletal MuscleMost numerous in bodyLooks striped (striated)Attached to the bones by tendons– Tendons—thick bands that pull on

the bone as the muscle contractsVoluntaryContract quickly, tire easily

Muscular SystemThree Types of Muscle Tissue (cont.)

2. Smooth MuscleInvoluntaryFound in: walls of stomach, intestine, uterus, etc.Contracts and relaxes slowlyNo striations

Muscular SystemThree Types of Muscle Tissue (cont.)

3. Cardiac MuscleOnly found in heartInvoluntaryHas striationsContracts 70 times per minute (heartbeat)

Muscles at Work Skeletal muscle movements are

results of pairs of muscles working together.

– One muscle contracts while the other muscle relaxes.

– Muscles always pull; they never push.

Muscles at Work Results of Muscle Action– Muscles contract

This produces thermal energy, and it uses chemical energy.

Thermal energy produces heat that helps keep body temperature constant.

Chemical energy is from glucose. (When glucose is used up, muscles are tired and need to rest.)

Muscles at Work

Results of Muscle action (cont.)– Over time, muscles become larger or

smaller, depending on how much work they do.

Skeletal SystemMade up of all of the bones in your body, it is the framework of the body.– Each bone in your body

is a living organ, made of different tissues.

Cells in bones take in food and use energy.

Skeletal SystemMade up of all of the bones in your body, it is the framework of the body.

- Five Functions of Skeletal System1. Framework gives shape &

support to the body.

Skeletal SystemMade up of all of the bones in your body, it is the framework of the body.

– Five Functions of Skeletal System1. Framework gives shape

and support to the body.2. Bones protect the internal organs.

Skeletal SystemMade up of all of the bones in your body, it is the framework of the body.

– Five Functions of Skeletal System1. Framework gives shape & support to the body.2. Bones protect the internal organs.3. Major muscles of the body

are attached to the bones.

Skeletal SystemMade up of all of the bones in your body, it is the framework of the body.

– Five Functions of Skeletal System1. Framework gives shape & support to the body.2. Bones protect the internal organs.3. Major muscles of the body are

attached to the bones.4. Blood cells are formed

in red marrow of some bones.

Skeletal SystemMade up of all of the bones in your body, it is the framework of the body.– Five Functions of Skeletal System

1. Framework gives shape & support to the body.2. Bones protect the internal organs.3. Major muscles of the body are

attached to the bones.4. Blood cells are formed in red

marrow of some bones.5. Skeleton is a place where

major quantities of calcium and phosphorus compounds are stored.

Bones

The adult skeleton has 206 bones (baby has 270).

JointsAny place where two or more bones meet

Ligaments: tough bands of tissue that hold bones together at the joints