Functions of the Muscular System

• Movement
• Posture
• Production (helps maintain a normal body temperature
• To hot? We sweat
• To cold? We shiver

Epimysium

•  Strong sheath covering the entire muscle
• Connects the the tendon

Perimysium

• Connective tissue binding muscle fibres together (sheath)

Endomysium

• Sheath of connective tissue surrounding the muscle fibre

Myofibrils

•       Thread-like structures run the entire length of the fibre
• Responsible for force generation and shortening 

Sarcomeres

•  Compartments containing actin and myosin
•  Smallest functional unit of muscle cell that undergoes contraction

• Attached to bones
• Striations (visible under a microscope)
• Voluntary: contracts by conscious control

• Located in the wall of hollow internal structures (stomach blood vessel)
• Involuntary control: contraction not under conscious control
• No striation (hence name- smooth)

Cardiac Muscle

• Forms the wall of the heart
• Striated (more muscles mass, the more striations there will be)
• Involuntary

• 40% of total Body weight

• Made up of brain and spinal chord

• Main control centre for movement, sleep, hunger, thirst and emotions

• Largest part f the brain subdivided into hemispheres and lobes
• Controls sensory, motor activities and intelligence

The Cerebellum

• Coordinate muscle movement and controls balance

The Brain Stem

• Links the cerebrum to the spinal cord 
• Responsible for autonomic functions (posture, eye, movement, muscle tone

• Consists of thalamus and hypothalamus
• Thalamus: relays sensory stimuli (pain, attention)
• Hypothalamus: controls body temperature, appetite

• Regulates basic drives (hunger, aggression)
• Screens info going to the cerebral cortex (decides where information goes)

The Reticular Activation System

• Directs incoming information to the correct processing centers

The Spinal Cord

• The main pathway for information connecting the brain and peripheral nervous system

• Consists of parts of the nervous system outside of the brain and spinal cord
• Consists of the Autonomic and Somatic Nervous Systems

• Involuntary contraction of cardiac and smooth muscles

The Sympathetic System

• Prepares the body for emergencies
• “The fight or flight response”
• Release of adrenaline, increased heart rate, sweating

• Helps return body to normal after the Sympathetic System (slows the heart rate)

• Allows us to be aware of our environment and cope with it
• Allows us to move our muscles in our extremities
• Composed of Efferent and Afferent Nerves

• Carries information from CNS to the body’s organs (in to out)

• Carries information from our body to the CNS (out to in)

Step 1: Afferent Nerves carry the information to the CNS

Step 2: The signal goes to the PNS à Sympathetic “ Fight or Flight” (drop or carry)

Step 3: The signal goes sup the spinal cord to the reticular activating system

Step 4: Diencephalon à Thalamus recognizes pain (controls sensory recognizes: pain)

Step 5: Next, the Cerebellum and cerebrum sends message to move your arm

Step 6: Signal goes to the CNS

Step 7: Then to the PNS. And the Efferent nerves force you to move your arm

• Passage of air from outside the body to the lungs
• Gas exchange to occur

1.     Supply O2to the blood

2.    Remove CO2

3.     Regulates blood pH (acid-base balance)

• Conductive zone
• Respiratory zone

• Composed of structures that transport air to the lungs

  Mouth and nose

  Larynx

Trachea

Primary and secondary bronchi

Tertiary and terminal bronchioles

• Filters air taken in with each breath

• The respiratory zone is composed of structure involved with the exchange of gases
• Consists of

  Respiratory bronchioles

 Alveolar ducts

Alveolar

• Contraction of the diaphragm
• Thoracic cavity expands
• Air pressure in thoracic cavity is lower that air pressure outside the body
• Air rushes in to lungs to restore balance
• Lung pressure is equal to atmospheric pressure

• Alveolar sacs recoil as a diaphragm relaxes
• Air is expelled
• Thoracic cavity reduces
• Lung pressure is greater than atmospheric pressure

ATP

• Is the universal form of energy
• When it breaks down it becomes ADP+ P (phosphate)+ Energy

• Without oxygen
• 10-15 seconds of activity which require a large burst of energy
• Energy comes from PC (phosphocreatine), a high energy molecule
• PC+ADPàATP + Creatine
• Muscles do not have large supplies of PC, therefore this system is depleted within seconds
• Muscles require 2-3 minutes of recovery time to recombine the phosphate ad the Creatine
• Examples:

100m dash

Shot put

High jump

Olympic weight lifting

• Without oxygen
• 1-3 minutes of activity
• Glucose is partially broken down to provide ATP
• By product produced due to the lack of oxygen is pyruvate
• Pyruvate is converted t lactic acid
• Lactic Acid causes muscle exhaustion or pain (burning sensation), hampers the breakdown of glucose and, decreases the ability of the muscle fibres to contract
• Lactic acid removal requires 30-60 minutes of exercise recovery or 1-2 hours of rest recovery
• Examples

400 m

800 m

Shift in hockey

• Oxygen required
• Activity longer than 90 sec
• Fats are the primary energy source in activity longer than 20 minutes
• 36 ATP are produced for every molecule of glucose
• 3 separate sub-pathways
• Glycolysis

Now pyruvic acid is converted to Acetyl CoA (instead of lactic acid)

Acetyl CoA then enters the Krebs Cycle

• Krebs Cycle

8 reactions take place producing 2 ATP molecules

• Electron Transport Chain

Large amounts of ATP are produced

Carbon Dioxide (CO2) and water as by-products

• Examples

Soccer

Marathon runners

Basketball

Asthma (acute or chronic) is characterized by:

• Spasm of smooth muscle lining of the respiratory system
• Over secretion of mucus
• Swelling of cells lining the respiratory tract

Asthma results in

• Dyspnea (shortness of breath)
• Wheezing during breathing

• Exercise
• Allergic reactions/contaminates
• Stress

• The use of medication

• Diffusion is the movement of a gas, liquid, or solid from a region of high concentration to low concentration
• Can only occur if there is a difference in concentration between gradients

• Area through which gases move from the lungs into the blood; from the blood into the tissue, and back.
• Rates of diffusion depend on:

• In the lungs, thousand of capillaries make contact with thousands of alveoli
• Exchange of Co2 and O2 take space between the blood and alveolar space by diffusion
• Concentration of CO2 in blood is greater in alveolar space, therefore natural diffusion of CO2 out of blood and into alveolar space
• Same is true for oxygen but in reverse

• Hemoglobin aids the natural process of diffusion between the alveolar space and the blood
• Hemoglobin (HbO2) has the effect of “ fooling” the diffusion process because the O2 enters the blood and combines with it and “ ideas it”
• Therefor, diffusion keeps on working until all the Hemoglobin molecules are used in the blood cell
• As a result, the blood is able to absorb 60x more O2 than it would with ought Hemoglobin

• Nicotine binds to Hemoglobin as well as oxygen
• Your Hemoglobin has less space for an adequate amount of oxygen
• Therefor Hemoglobin can carry less oxygen because the nicotine molecules are already bonded and taking up the room of the oxygen
• And therefor the body tissues and muscles receive less oxygen than they should

• After O2 is exchanged in the tissues, the Hemoglobin combines with CO2 to form Carbaminohemoglobbin (HbNHCOOH), which is carried in the lungs for diffusion into the environment.

• Too much acid in the blood (normal blood pH is 7.4)
• CO2 is acidic, therefore acidosis occurs when too much CO2 is found in the blood
• EX: holding your breath

• Less frequent, occurs when respiration is overactive
• EX: hyperventilation
• Too little Carbon Dioxide in the blood (pH 7.5 or 7.6)
• Body maintains homeostatis by realising or holding CO2 back to maintain balance (Autonomic System)

• Heart
• Blood Vessels
• Blood 

• Delivery of oxygen, fuel, and nutrients to the cells and tissues of the body
• Removal of carbon dioxide and waste products rom the tissues
• Maintenance of constant body temperature (thermoregulation)
• Prevention of infection (immune function)

• Red in colour due to more capillaries (need more oxygen)
• Contract for a long time
• For long-term aerobic activity (Ex. Marathon)
• Example of Muscle

Rectus Femoris (Top Quad)

Soleus (Shin)

Rectus Abdominus (Abs) 

• White due to lack of capillaries 
• Contract quickly and fatigue rapidly
• Rapid release of energy for explosive activities or speed (Ex. Sprinting)
• Do not rely on oxygen - anaerobic
• Examples of Muscles

Gastrocnemius (Calf)

Latissimus Dorsi (Back)

Biceps (Arm)

Deltoid (Shoulder)

• Allows no movement
• bound by connective tissue

• slight movement
• cartilage connects bone to bone

• allows most movement
• bones are seperated by fluid, cartillage and ligaments

• Connects flat or slightly curved bones (Ex. Tarsal)

• Convex portions fit into concave portion (Ex. Unla and Humerus)

• one bone rotates around another (Ex. Atlas and Axis) 

• Movement in 2 planes (Ex. Wrist)

• Ball shape of one bone fits into the socket of another (Ex. Acetabulum)

• proximal attachment - where muscle is attached to the least movable area (bone) on axial skeleton

• Distal attachment - where muscle attaches to most movable area

• Action (Motion) 0 what muscles does when activated

• Most common
• Occurs when muscle is SHORTENING (Ex. Bicep curl) as it develops tension

• Occurs when muscle is LENGTHENING (Ex. Pushing Up from the ground when doing a push up) as it develops tension

• Occurs when there is no change in muscle length (Ex. The "chair" exercise)
• Still has tension and muscle contracts

• Both concentric and eccentric contractions