Presentation on theme: "Review Questions begin on page 198"— Presentation transcript:
1 Review Questions begin on page 198 Muscular SystemRead Ch 6Review Questions begin on page 198S/A #2, 7, 10, 12, 18, 20, 21At the Clinic #2, 5, 6
2 OverviewOver ½ of body’s mass is muscle—90% of that is skeletal muscleThese contractile cells have high energy needs, so it’s common to see an ample blood supply associated with muscles
3 Overview con’t:Blood provides glucose and oxygen while removing metabolic waste productsMuscles (and nervous tissue) consume almost 70% of the food energy taken into your body dailyMuscle is as intensive a consumer of calcium as is the skeletal system—much of the Ca stored in bones is made available for the muscles’ needs.
4 Categorizing muscles Microscopically Nonstriated (no lines) MicroscopicallyNonstriated (no lines)Striated (lines running through)micro.magnet.fsu.edu/
5 Categorizing muscles Controllability Involuntary (no control) Voluntary (control)
6 Categorizing muscles Location Cardiac: Involuntary, only found in heartSmooth: Involuntary, lines digestive organsSkeletal: voluntary muscles found attached to bones
7 Functions of the Muscular System Movement of body parts—by pulling on bones. Bones act as levers, joints as the fulcrum.Guard entrances and exitsPostureStabilizing jointsCreate heat
8 Physiology of muscleContraction is achieved by the simultaneous shortening of all the sarcomeres within a cell.Three stages:Neural stimulationContractionRelaxation.
9 Neural Stimulation Takes place at the neuromuscular junction. The nerve cell releases a neurotransmitterneurotransmitter—a chemical used for cell to cell communication.
10 Neural StimulationMuscles respond to the neurotransmitter acetylcholine (Ach).Ach binds to receptors on the sarcolemma.The binding of Ach affects the transport of ions across the sarcolemma
11 Neural StimulationIn a resting muscle, the concentration of sodium ions is normally higher in the fluid outside the muscle cell while the concentration of potassium ions is higher inside the cell.Sodium/potassium pumps maintain these unequal ion concentrations.upload.wikimedia.org/wikipedia/commons/thumb/...
12 Neural StimulationThis imbalance produces an unstable condition. When stimulated by Ach the membrane loses its ability to maintain the imbalance.Once the membrane is stimulated, it opens the ion channels permitting the free flow of sodium into the muscle cell and potassium out of the cell.In turn, calcium stored in the sarcoplasmic reticulum is released to begin the contraction phase
13 Muscle ContractionWhen calcium (released by the sarcoplasmic reticulum) binds to the troponin, contraction begins.Troponin sits on tropomyosin on the same region where actin binds to myosin.
14 Muscle ContractionCa bumps troponin off the binding site, permitting myosin to attach to actin.Troponin also transmits info that activates ATP synthesis around the myosin. The ATP provides energy for the myosin head to swivel and pull the myosin toward the actin.
17 Muscle RelaxationRelaxation occurs when there are no more neural stimulations exciting the sarcolemma. The sodium and potassium ion levels are completely recoveredThe sarcoplasmic reticulum has retrieved most of the Ca, causing the release of the myosin heads from the actin.There is no mechanism for the muscle cell to lengthen (so we’ll discuss how that happens later in the lecture).
26 Contraction in Action--Skit Links to put on website
27 Muscle cell structure Animation of entire process… Video of sarcomere shortening
28 Review Nerve impulse arrives at muscle cell Ca+2 released from SR into sarcoplasmCa+2 combines with troponin molecules in the thick filaments of myofibrils (Myosin)Troponin without Ca+2 doesn’t interact like thisMyosin interacts with Actin and pulls toward centerContraction of muscleAnimation of entire process…
29 Other factors found in muscle fibers ensuring adequate muscle contractions: Creatine Phosphate: stores energy in muscle cells. It collects this energy from ATP and is capable of storing it for long periods of time.Glycogen (stored form of glucose) can supply glucose when muscles cells need it to produce ATPMyoglobin is a chemical that stores oxygen for certain muscle cells. This O2 permits muscle cells to provide large amounts of ATP during continuous or heavy work.
30 Muscle Attachment Fibers Tendons—connect muscle to bone (cordlike)Aponeuroses—connect muscles to muscles (sheetlike)
31 Musculature terms Origin—fixed end (proximal end of bone) Insertion—moveable end (distal end of bone)
32 Skeletal Muscle Action Muscle cells either contract or don’t…so we get graded effects based on contraction of more individual fibers at the same time.Strength is achieved by stimulating more individual fibers to fireEndurance is achieved by producing contraction and relaxation groups working together.
33 Skeletal Muscle Action Antagonistic effects occur when one muscle opposes or resists the action of another muscle.—if nothing else, your muscles are acting against the antagonistic force of gravityThe antagonistic actions are essential for pulling the relaxed muscle cells back to their original length.
34 Skeletal Muscle Action Synergistic effects occur when muscles work together to produce a common end result…the muscles of the forearm work synergistically with the muscles of the fingers to produce a fist.
35 5 golden rules of skeletal muscle All muscles cross at least one jointTypically the bulk of the muscle lies proximal to the joint crossedAll muscles have at least two attachments, the origin and the insertionMuscles can only pull; they never pushDuring contraction, the muscle insertion moves toward the origin
36 Body MovementsFlexor—decreases the angle of the joint by bringing the bones closer togetherExtensor—extends a joint by increasing the angle between the bones
37 Body Movements Rotator—movement around an axis (partway around) Tensor—important posture/positioning muscles that make a body part more rigid or tense.
38 Body Movements Abduction—moving away from the midline Adduction—moving toward the midline
39 Body Movements Depressor—produce a downward movement Levatator—provide an upward movementSphincter—decreases the size of an opening
40 Special Movements Pronator—motion of palm downward Supinator—palm moves upward
41 Special Movements Inversion—turning the sole of your foot medially Eversion—turning the sole of your foot laterally
42 Special Movements Dorsiflexion—pointing your toes up toward your shin Plantar Flexion—pointing your toes downward
44 Rigor MortisCalcium leakage out of the sarcoplasmic reticulum into the sarcomere. Common after death. Eventually, the muscle cells structures start to decay, causing the muscles to become soft and loose.
45 Strain Most common muscle ailment An injury due to overworking the muscle’s force on the joints.Injury to the tendon or muscle tissue
46 SprainA sprain is an injury to a ligament. (A ligament is a thick, tough, fibrous tissue that connects bones together.)Ligaments prevent abnormal movements. When too much force is applied to a ligament they can be stretched or torn.
48 Muscle SpasmsInvoluntary, abnormal contractions of a muscle or muscle groupCaused by a wide range of medical conditions
49 Muscle Cramp Painful contraction of a muscle Extreme muscle exertion is the most common cause of cramps, although certain poisons and bacterial infections can also cause muscle cramping
50 Paralysis Complete failure of a muscle function Rigid paralysis—excessive muscle stiffnessFlaccid paralysis—complete lack of muscle contractionMany causes…including spinal injury and poisoningEg: Tetanus--Caused by soil bacteria that produces poisons that cause rigid paralysis
51 Dermatomyositis Inflammation of the muscle and overlying skin. Cause: unknown, but it can be treated with drugs (to reduce inflammation) and sun avoidance
52 Muscular dystrophiesGroup of conditions that involve progressive weakness in the voluntary muscles.Usually due to the inability of the nervous system to stimulate muscle actionEventually results in muscle atrophy and wasting.esciencenews.com
53 TetanyCalcium imbalance disease that causes extended periods of spasms in the arm and leg muscles.Do NOT confuse this with the bacterial disease tetanus!
54 CachexiaType of muscle loss associated with diseases such as AIDS and cancer.Also found in starvation and a common consequence of anorexia and bulimia
55 CachexiaA slower form is a normal consequence of aging b/c the body reduces its ability to rebuild muscle structure as you age.Brought about by sedentary lifestyles—resulting from other age related illnessesNeural stimulation also is lessened as you age; important for muscle upkeep
56 Nutritional issues with muscle loss Protein turnover: muscles need lots of protein to maintain their integrityMalnutrition and undernutrition as we age greatly affects protein turnover.Can be caused by poor diets or income levelsLack of appetite as we age is another contributing factorAs we age, our digestive system can’t absorb some of the impt amino acids needed for muscle cell growth/maintenance.
57 Muscle atrophy—other causes Decline in sex hormones and other chemical messages needed for muscle cell growth, maintenance and repair.Insulin-like growth factor-1: known to lessen with maturityCytokines cause muscle atrophy and are known to increase with age