Muscular System
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