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.

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

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

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.

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 30-40 seconds. Drawbacks: Uses a large amount of glucose for small amount of ATP Accumulating lactic acid promotes muscle soreness (burning sensation).

 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

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.

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.

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).

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

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

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

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).

 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

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.

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

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.

 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

Crash Course: Muscle Cells; A&P #21 https://www.youtube.com/watch?v=Ktv-CaOt6UQ Start at 3:25 Crash Course: Muscles, part 2 - Organismal Level; A&P #22 https://www.youtube.com/watch?v=I80Xx7pA9hQ