1. Energy And Exercise and Muscles
Objectives
I will be able to:
describe how muscle cells obtain and utilize energy.
describe the effects of exercise on muscles.

2. Energy for Muscle Contraction
Muscles use stored ATP for energy
Bonds of ATP are broken to release energy
After this initial use, other pathways must be utilized to produce ATP
ATP: (adenosine triphosphate) a nucleotide that contains a large amount of chemical energy stored in its high-energy phosphate bonds
Direct phosphorylation
Muscle cells contain creatine phosphate
After ATP is depleted, ADP is left
CP transfers a high-energy phosphate group to ADP, to regenerate ATP

3. Energy for Muscle Contraction
Aerobic Respiration (Cellular respiration)
Series of metabolic pathways that use oxygen and occur in the mitochondria (oxidative phosphorylation).
Glucose is broken down to carbon dioxide and water, transferring energy to the ATP bonds.
This is a slow reaction that provides 32 ATP/glucose molecule and requires continuous oxygen

4. Energy for Muscle Contraction
Anaerobic glycolysis
The glycolysis reaction breaks down glucose without oxygen.
Glucose is broken down to pyruvic acid and produces only 2 ATP/glucose molecule.
If oxygen is present, pyruvic acid enters aerobic respiration.
If oxygen is not present, pyruvic acid is converted to lactic acid.

5. Energy for Muscle Contraction
Anaerobic glycolysis only produces 20% of the ATP aerobic respiration does but is 2½ times faster and can provide most of the ATP needed for strenuous exercise for seconds.
Drawbacks:
Uses a large amount of glucose for small amount of ATP
Accumulating lactic acid promotes muscle soreness (burning sensation).

6. 
What is the major difference between unfused tetanus and fused tetanus?
When do muscles use anaerobic glycolysis?
Unfused – muscle relaxes between contractions; Fused – muscle does not relax, maintains steady contraction
When oxygen is not available

7. Muscle Fatigue and Oxygen Deficit
Muscle fatigue occurs when a muscle is unable to continue contractions even though still being stimulated.
The major factor for muscle fatigue is oxygen deficit.
Oxygen deficit happens when oxygen is not replaced fast enough to keep up with vigorously working muscles.
Increase acidity (from lactic acid) and the lack of ATP also causes the muscle to contract less.
To overcome oxygen deficit:
Oxygen must be replaced to rid the muscles of accumulated lactic acid.

8. Types of Muscle Contractions
Muscles do not always shorten during contractions.
Muscle tension always develops during contractions.
Isotonic contractions
Myofilaments are able to slide past each other during contractions.
Tension in the muscles increases.
The muscle shortens.
Isometric contractions
The muscle is unable to shorten.

9. Types of Muscle Contractions
muscle tone: sustained partial contraction of a muscle in response to stretch receptor inputs
Muscle tone keeps the muscle healthy and ready to react.
If the nerve that attaches to a muscle is damaged, the muscle is no longer stimulated.
The muscle will become flaccid (soft and flabby) and begin to atrophy (waste away).

10. Effects of Exercise on Muscle
The amount of work a muscle does changes the muscle.
Muscle inactivity leads to muscle weakness and wasting.
Regular exercise leads to increased:
Muscle size
Strength
Endurance

11. Effects of Exercise on Muscle
Exercise falls into two categories:
Aerobic or endurance exercise
Resistance or isometric exercise
aerobic exercise: any of various sustained exercises that stimulate and strengthen the heart and lungs, thereby improving utilization of oxygen
resistance exercise: any exercise that causes the muscles to contract against an external resistance with the expectation of increases in strength, tone, mass, and/or endurance

12. Effects of Exercise on Muscle
Benefits of aerobic exercise:
Stronger, more flexible muscles
Greater resistance to fatigue
Improves aerobic respiration efficiency
Overall body metabolism is more efficient
Improves digestion and elimination
Enhances neuromuscular coordination
Strengthens the skeleton
The heart enlarges and improves pumping ability
The lungs improve gas exchange efficiency

13. Effects of Exercise on Muscle
Resistance exercise requires little time and no special equipment.
Resistance exercise requires forcing your muscles to contract with as much force as possible.
Benefits of resistance exercise:
Increased muscle size and strength
Individual muscle fibers enlarge by making more contractile myofilaments (the number of fibers remains the same).

14. 
Gary is trying with all his might to pull a tree stump out of the ground. It does not budge. Which type of contraction are his muscles performing?
What is meant by the term oxygen deficit?
isometric
when you cannot take in oxygen fast enough to keep up with muscle usage

15. Five golden rules of skeletal muscle activity
With a few exceptions, all skeletal muscles cross at least one joint.
Typically, the bulk of skeletal muscle lies proximal to the joint crossed.
All skeletal muscles have at least two attachments, the origin and the insertion.
Skeletal muscles can only pull; they never push.
During contraction, a skeletal muscle insertion moves toward the origin.

16. Muscle Movements The origin is the anchor or leverage point.
Movement occurs when muscles contract across joints.

17. Types of body Movements
Flexion: decreases the angle of the joint and brings two bones together
Extension: increases the angle between two bones or parts of the body
Rotation: movement of a bone around its longitudinal axis
Abduction: movement of a limb away from the median plane of the body
Adduction: movement of a limb toward median plane
Circumduction: a combination of flexion, extension, abduction, and adduction, forming a cone-shaped movement.

18. 
What action is being performed by a person sticking out his thumb to hitch a ride?
What actions take place at the neck when you nod your head up and down?
Abduction
Flexion and extension

19. Crash Course: Muscle Cells; A&P #21
Start at 3:25
Crash Course: Muscles, part 2 - Organismal Level; A&P #22