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Muscular System

Muscular System

• Muscles are responsible for all types of body movement

• 3 basic muscle types are found in the body

– Skeletal muscle

– Cardiac muscle

– Smooth muscle

Comparison of Types of Muscle

Types of Muscle, cont.

Skeletal Muscle Characteristics

• Most attach to bones by tendon

• Cells are multinucleate

• Striated—have visible binding

• Voluntary

• Cells surrounded & bundled by connective tissue

Smooth Muscle Characteristics

• Has no striations

• Spindle-shaped cells

• Single Nucleus

• Involuntary—no conscious control

• Found mainly in the walls of hollow organs

Characteristics of Cardiac Muscle

• Has striations

• Usually has a single nucleus

• Joined to another cardiac muscle cell

• Involuntary

• Found only in the heart

Skeletal Muscle

• Functions of Skeletal Muscle – Produce Movement – Maintain posture – Stabilize joints – Generate Heat

• Sites of Muscle Attachment – Bones – Cartilage – Connective tissue

coverings

• Muscle Fibers blend into a connective tissue attachment – Tendon—cordlike structure – Aponeurosis—sheet-like structure

• Properties of Muscle – Irritability – ability to receive and

respond to a stimulus – Contractibility – ability to shorten

when an adequate stimulus is received

– Extensibility – ability to lengthen when an adequate stimulus is received

– Elasticity – ability to return to normal shape

Anatomy of a Muscle Cell

Voluntary/Involuntary

• What does it mean to volunteer?

• What does it mean to do something involuntarily?

• Which muscles are voluntary?

• Which are involunatry?

Skeletal Muscle Strength

• Two speeds at which muscles contract

• Slow Twitch - Have more endurance, have many more mitochondria to give them lots of energy.

• examples of when slow-twitch are needed:

• Marathons and swimming

•

Muscle Strenght

• Fast Twitch Muscles

• Fatigue Easier because of fewer mitochondria, but gives lots of strength. Rely more on anaerobic respiration.

• Examples where fast-twitch would be used:

• Sprinting, and weight lifting

Muscle Strength

• Some people have a high ratio of slow-twitch to fast-twitch, and some have a high ratio of fast-twitch to slow-twitch

• Most people are in between

Cellular Respiration

• Where does it occur?

• Sugar (C6H12O6 + O2

= CO2 + H2O + ATP (energy)

How do the Respiratory, Circulatory, and Muscular System all tie together? How does the nervous system work with all of these systems as well?

Skeletal system

Why wouldn’t the skeleton cross the road?

• Skeletal system protects vital organs and provides support

• Bone Marrow produces red and white blood cells

The nervous system

Main Function:

This communication system controls and coordinates functions

throughout the body and responds to internal and

external stimuli.

Our nervous system

allows us to feel pain.

What is the nervous system

made up of?

• The brain

• The spinal cord

• The nerves (neurones)

The central nervous

system (or CNS for short)

is made up of the brain and the spinal cord.

What is the job of the nervous

system?

Our survival depends on us being

sensitive to our surroundings. We need

to be able to detect any changes and be

able to respond to them.

What are our sense organs?

The sense organs are:

• The eyes

• The ears

• The nose

• Tongue

• skin

These organs sense:

• Light

• Sound and balance

• Smell

• Taste

• Pressure, pain, temperature

A nerve is an organ

containing a bundle

of nerve cells called

neurons.

Neurons carry

electrical messages

called impulses

throughout the

body. Picture shows hundreds of

severed neuron axons

Parts of a Neuron 1. Cell body: contains nucleus & most of the

cytoplasm

2. Dendrites: projections that bring impulses into the neuron to the cell body.

3. Axon: long projection that carries impulses away from cell body

1

3 2

Because neurons never touch, chemical signalers called neurotransmitters must travel through the space called synapse between two neurons.

Video Neurotransmitters

Synapse (gap)

The message

is transferred

when

RECEPTORS

receive

neurotrans-

mitters.

(pink

spheres)

Sensory

Neuron

Interneuron

Motor Neuron Sensory

Neuron

Interneuron

Motor

Neuron

Muscle

Contracts

Synapse

Synapse

Synapse

The knee jerk reflex action Sometimes

called a

relay or

Connector

neurone

Another reflex action

Examples of responses

Voluntary actions

• Eating a cake

• Riding a bicycle

• Walking

• Playing the piano

• Coming to school

Involuntary actions

• Your heart beat

• Breathing

• Blinking

• Removing hand

from hot object

• Choking

• Salivating