zoology 100 notes 5

8/14/2019 zoology 100 notes 5

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ZOOLOGY 100 NOTES (5).mid

Muscular SystemMYOLOGY

Functions of the muscular system1. For production of movements/locomotion2. Maintenance of posture3. Stabilize joints4. Generation of heat5. Influence body contours6. For expression of emotion7. For storage and movement of substances8. Allows one to manipulate the environment

Properties of muscles1. Excitability

- action potentials2. Conductivity3. Contractility

- isometric contraction- isotonic contraction

4. Extensibility5. Elasticity

Overview of muscle tissues THE THREE TYPES OF MUSCLES

1. SKELETAL2. SMOOTH3. CARDIAC

Differences of Muscle Tissues

BASIS SKELETAL SMOOTH CARDIAC

1.Location Bones Visceral organs heart

2. Shape Elongated Fusiform Elongated,branched

3. # of nuclei Many Single Single

4. NuclearPosition

Peripheral Central Central

5. Striation Present Absent Present

6. Contraction Rapid Slow Moderate

7. Stimuli Electrical Chemical electrochemi-cal

BASIS SKELETAL SMOOTH CARDIAC


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8. FiberDiameter

10-200 cm 30-200 um 50 100 um

9. Organizationof CHONSintosarcomere

Yes No Yes

10. SR Present Present Scanty11. Gap

JunctionsNo Yes Yes single unit muscle,

no for multi-unit

12.Authorhythmi-city

No Yes Yes

13. Source of Caions

SR SR SR and ECF

14. Regulationof contraction

Acetylcholine releasedby somatic motorneurons

Ach,NE for ANS motorneurons,hormones

Ach,NE for ANS motorneurons,Hormones,chemical

changes


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Organization of muscle tissue1. Superficial Fascia

- separates the muscle from the integument- made up of areolar and adipose tissue that

a. insulate heat and reduce heat lossb. provides pathway and framework for nerves, blood vessels, lymphatic vessels toenter and leave musclesc. stores water and fatsd. provides mechanical protection and prevent physical trauma

2.Deep Fascia- with dense irregular conn. tissue that lines the body wall- 3 layers: epimysium, perimysium, endomysium


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- functions:a. Holds the muscle togetherb. Allows movement of musclesc. Supports nerves,blood vessels and lymphaticd. Fill spaces between musclese. separates the muscles into functional units

Deep Fascia1. Epimysium - tough, overcoat connective tissue that covers the entire muscle

a. tendon strong, thick, cord-like attachment of muscle to bone- provide durability and conserve space

b. aponeurosis broad, thin, sheet-like attachment of muscle to bone, cartilages, orconnective tissue covering of each other

ORGANIZATION OF MUSCLES

2. Perimysium- coarse fibrous membrane that covers muscle fascicles- fascicles bundles of muscle fibers

3. Endomysium- delicate connective tissue sheath that enclose the individual muscle fiber


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Microscopic anatomy of skeletal musclesMYOCYTE/myofibrils - muscle cellsSARCOLEMMA plasma membrane of muscle cellsSARCOPLASM cytoplasm of muscle cells occupied by myofilamentsSARCOMERE functional units of muscle cells

- z line to z line in locationMYOFILAMENTS thread-like contractile proteins of myocytes

Types of Myofilaments1. MYOSIN - thick myofilament that characterized the A band,

- mostly made of bundled molecules of protein myosin

- types: a. HEAVY MEROMYOSIN- thick, with globular heads which contain the actin binding site and ATPase siteb. LIGHT MEROMYOSIN- thin, tail to tail arrangement of myosin


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2. ACTIN thin myofilament that characterize the I band Types:a. Actin the principal globular CHON

- with myosin binding siteb. Tropomyosin filamentous CHON that covers the myosin- binding site of actinc. Troponin triplet CHON which are in constant interval in the actin

c.1 Tn-Tc.2 Tn-Cc.3 Tn - I

SKELETAL MUSCLE ACTIVITY Irritability


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ContractilityNerve impulse and Action Potential

- skeletal muscles must be stimulated in order to contract- one or more neuron may stimulate a muscle fiber of groups of muscle fibers

THE MOTOR UNIT The neuron and the muscle fibers stimulated

TYPES OF MOTOR UNITS1. SINGLE MOTOR UNIT2. MULTIPLE MOTOR UNIT

THE NEUROMUSCULAR JUNCTION The region where motor neurons comes in close contact with the skeletal muscle cellComposition:

a. Motor neuronb. Synaptic cleftc. Synaptic vesicles containing Neurotransmitter (ACh)d. Axonal terminal


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The Sliding Theory (Mechanism of contraction)1. Stimulation across the neuromuscular junctin initiates an action potential, or

depolarization, on the sarcolemma of the muscle fiber. This action potential spreads alongthe sarcolemma and is transmitted into the T-tubule

2. The T-tubule potential causes the terminal cisternae of the sarcoplasmic reticulum torelease Ca in the immediate vicinity of each myofibrils

3. Ca ions bind to and thereby change the CHON structure of the troponin molecules attachedto the tropomyosin to move aside to expose the actin-binding site

4. Myosin across bridges bind to actin.Upon binding, the energized HMM undergoues aconformational change, causing the head to tilt.This pulls the actin filament over myosin inan action called power stroke

5. 5. After power stroke, ATP binds with HMM, causing detachment of the cross bridge fromthe actin-binding sites. The enzyme ATPase within HMM cleaves ATP to ADP and energy toenergize the HMM. Then the HMM can then bind with another actin-binding site andproduce another power stroke.

6. Repeated power strokes pulls the actin filament, much like pulling a rope hand over hand.


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GRADED RESPONSE

In skeletal muscles, the all-or-nonelaw of muscle physiology applies to the muscle cell,not to the whole muscleAll muscle contract to its fullest when stimulated adequately, it never contract partiallySkeletal muscles react to stimuli with different degrees of shorteningGraded contraction may in 2 ways:

1. By changing frequency of muscle contraction2. By changing number of muscle cells stimulated

MUSCLE TWITCH The single, brief, jerky contractions sometimes result due to some nervous systemproblemsIn a twitch, single stimulus is delivered, a muscle contracts and then relax3 phases:

1. Latent period2. Contraction period3. Relaxation period


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ENERGY FOR MUSCLE CONTRACTION1. Direct phosphorylation of adp by creatine phosphate2. Anaerobic Respiration 5 % of the ATP used by the muscle but 2.5 times faster in providingenergy3. Aerobic Respiration 95% of the energy used by the muscle


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TYPES OF MUSCLE FIBERS

FIBER CXCS FAST-TWITCH INTERME-DIATE SLOW TWITCH

Fiber size Large Intermediate Small

Glycogen content High Intermediate Low

Myosin ATPase High High Low

Myoglobin Low High Low

Energy Anaerobic Combination Aerobic Twitch Fast Fast Slow

Primary Use Speed & power Moderate activity Endurance


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TYPES OF MUSCLE FIBER

Muscle fatigue and Oxygen Debt-

Muscle fatigue occurs due to strenous activity for a long time- Muscles are unable to contract even if they are stimulated- Fatigue results due to oxygen debt that occurs due to porlonged muscular activity

MUSCLE TONE The state of continuous partial contractions of muscles The results of different muscle motor units that are scattered throughout the muscle, beingstimulated by the nervous system in a systemic way.

TYPES OF MUSCLE TONE1. HYPOTONIA

- decreased or loss of muscle tone resulting to flaccid paralysis due to damagedsomatic motor neurons

- cxcs: loss or decreased tendon reflexesatrophyloss of muscle tone

2. HYPERTONIA increased muscle tone 2 ways of hypertonia SPASTIC HYPERTONIA

- cxc. By increased muscular tone (stiffness) associated with increased intendon reflexes and pathological reflexes- results to spastic paralysis

b. RIGID HYPERTONIA


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- refers to conditions associated with increased muscular tone but thereflexes are not affected.

TYPES OF MUSCLE CONTRACTION1. ISOTONIC CONTRACTION

-tension always remain almost constant- occurs when one move a constant load through the range of motion possible at a joint- 2 types:a. CONCENTRIC ISOTONIC CONTRACTION- muscles shortens, angle between joints is reducedb. ECCENTRIC ISOTONIC CONTRACTION- occurs when overall length of the muscle increases during contraction

2. ISOMETRIC CONTRACTIONOccurs when muscle does or cannot shorten, but tension of the muscle increases greatly

The 2 forces- contraction and strengthening that are applied in opposite directions createthe tensionImportant because they stabilize joints as others are moved

RIGOR MORTIS The resulting condition in which muscles are in the state of rigidity

Lasts for about 24 hours but disappears as the tissues begin to disintegrateAfter death, myofibrils and calcium ions leak out of the sarcoplasmic reticulum

EFFECTS OF EXERCISE TO MUSCLERegular exercise increases muscle size, strength, and enduranceAerobic exercise such as jogging,biking results in stronger,more flexible muscles withgreater resistance to fatigueAerobic exercise causes the heart to enlarge thus increase the amount of blood pumpedWeight-lifting exercise will cause hypertonia and increase in strength

INVERTEBATE MUSCULATURE1. PROTOZOANS: CILIA, FLAGELLA,PSEUDOPODIA2. MOLLUSKS: VENTRAL MUSCLE

3. NEMATODES: CIRCULAR FIBERSLONGITUDINAL FIBERS

4. PLATYHELMINTHS: CIRCULAR, LONGITUDINAL,DORSO-VENTRAL MUSCLE5. ECHINODERMS: TUBE FEET


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1. Dorsilexion2. Plantarflexion3. Inversion4. Eversion5. Supination6. Pronation7. Opposition

TYPES OF MUSCLE ACCORDING TO MOVEMENT1. AGONISTS/ Prime Mover2. ANTAGONIST3. SYNERGISTS4. FIXATORS

NAMING SKELETAL MUSCLES1. DIRECTION OF MUSCLE FIBERS2. RELATIVE SIZE3. LOCATION4. NUMBER OF ORIGINS5. ATTACHMENT/ LOCATION OF ORIGINS AND INSERTION6. SHAPE OF THE MUSCLE7. ACTION/FUNCTION

DEVELOPMENTAL ASPECT OF MUSCULAR SYSTEM1. Increasing muscular control reflects the maturation of the nervous system. Muscle control

is achieved in cephalic/caudal and proximal/distal direction2. To remain healthy, muscles must be regularly exercised to prevent atrophy and

hypertrophy3. As we age, muscle mass decreases and muscles become sineway. Exercise to help retain

muscle mass and strength.

COMMON MUSCLE DISORDERS1. TORTICOLIS2. TICS3. FIBROMYALGIA4. BALLOON CHEEKS5. HIGH HEEL SYNDROME6. HERNIA

A. HIATAL HERNIAB. INGUINAL HERNIAC. UMBILICAL HERNIA

7. SPRAIN AND STRAIN R-I-C-E THERAPY8. MYASTHENIA GRAVIS9. MUSCULAR DYSTROPHY

TORTICOLIS

MYASTHENIA GRAVIS


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HIGH HEEL SYNDROME

HIATAL HERNIA

UMBILICAL HERNIA

Inguinal Hernia


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MYASTHENIA GRAVISAn autoimmune disease that causes progressive,chronic damage og the neuromuscular

junction The immune system inapproppriately produce antibodies that bind to and block AChreceptors,thereby causing decreasintg number of functional ACh receptors thus musclebecome weaker,fatigue easily and eventually cease its function.Occurs in 1 out of 10,000 people ,common in women (20-40Yrs old onset), than men (50-60 onset)70% of the patients have hyperlasia in thyumus

MYASTHENIA


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ABNORMAL MUSCLE CONTRACTIONS1. SPASM a sudden involuntary contractions of a single muscle in a large group of

muscles2. CRAMP a painful spasmodic contraction3. TIC a spasmodic twitching made involuntarily by muscle that are ordinarily under

voluntary control- eyelid and facial muscles

4. TREMOR a rhythmic,involuntary,purposeless contraction that produces quivering orshaking movement

5. FASCICULATION an involuntary,brieg twitch of an entire motor unit that is visible underthe skin

- occurs irregularly but is not associated with movement of the affected muscle as inMS or multiple sclerosis

6. FIBRILLATION a spontaneous contraction of a single muscle fiber that is not visible inskin but can be recorded by electromyography

- may signals destruction of motor neurons

MEDICAL TERMINOLOGIESMYALGIA pain in or associated with musclesMYOMA a tumor consisting of muscle tissueMYOMALACIA - pathological softening of muscleMYOSITIS inflammation of muscle tissueMYOTONIA increased muscular excitability

and contractility with decreased power of relaxation

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