Presentation on theme: "Review Questions begin on page 198"— Presentation transcript:
1Review 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
2OverviewOver 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
3Overview 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.
4Categorizing muscles Microscopically Nonstriated (no lines) MicroscopicallyNonstriated (no lines)Striated (lines running through)micro.magnet.fsu.edu/
5Categorizing muscles Controllability Involuntary (no control) Voluntary (control)
6Categorizing muscles Location Cardiac: Involuntary, only found in heartSmooth: Involuntary, lines digestive organsSkeletal: voluntary muscles found attached to bones
7Functions 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
8Physiology of muscleContraction is achieved by the simultaneous shortening of all the sarcomeres within a cell.Three stages:Neural stimulationContractionRelaxation.
9Neural Stimulation Takes place at the neuromuscular junction. The nerve cell releases a neurotransmitterneurotransmitter—a chemical used for cell to cell communication.
10Neural 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
11Neural 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/...
12Neural 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
13Muscle 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.
14Muscle 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.
17Muscle 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).
26Contraction in Action--Skit Links to put on website
27Muscle cell structure Animation of entire process… Video of sarcomere shortening
28Review 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…
29Other 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.
30Muscle Attachment Fibers Tendons—connect muscle to bone (cordlike)Aponeuroses—connect muscles to muscles (sheetlike)
31Musculature terms Origin—fixed end (proximal end of bone) Insertion—moveable end (distal end of bone)
32Skeletal 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.
33Skeletal 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.
34Skeletal 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.
355 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
36Body MovementsFlexor—decreases the angle of the joint by bringing the bones closer togetherExtensor—extends a joint by increasing the angle between the bones
37Body Movements Rotator—movement around an axis (partway around) Tensor—important posture/positioning muscles that make a body part more rigid or tense.
38Body Movements Abduction—moving away from the midline Adduction—moving toward the midline
39Body Movements Depressor—produce a downward movement Levatator—provide an upward movementSphincter—decreases the size of an opening
40Special Movements Pronator—motion of palm downward Supinator—palm moves upward
41Special Movements Inversion—turning the sole of your foot medially Eversion—turning the sole of your foot laterally
42Special Movements Dorsiflexion—pointing your toes up toward your shin Plantar Flexion—pointing your toes downward
44Rigor 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.
45Strain Most common muscle ailment An injury due to overworking the muscle’s force on the joints.Injury to the tendon or muscle tissue
46SprainA 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.
48Muscle SpasmsInvoluntary, abnormal contractions of a muscle or muscle groupCaused by a wide range of medical conditions
49Muscle 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
50Paralysis 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
51Dermatomyositis Inflammation of the muscle and overlying skin. Cause: unknown, but it can be treated with drugs (to reduce inflammation) and sun avoidance
52Muscular 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
53TetanyCalcium imbalance disease that causes extended periods of spasms in the arm and leg muscles.Do NOT confuse this with the bacterial disease tetanus!
54CachexiaType of muscle loss associated with diseases such as AIDS and cancer.Also found in starvation and a common consequence of anorexia and bulimia
55CachexiaA 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
56Nutritional 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.
57Muscle 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