1. response to stretch
2. Cardiac Muscle
2.1. Function
2.1.1. pumping of blood in circulatory system
2.1.2. only found in heart
2.2. structure
2.2.1. single nucleus, striated
2.2.1.1. sarcomeres
2.2.1.1.1. respond to signal and contract
2.2.1.1.2. made of actin & myosin
2.2.1.1.3. tropomyosin
2.2.1.1.4. troponin
2.2.2. heart muscles
2.2.2.1. 3 layers
2.2.2.1.1. epicardium
2.2.2.1.2. visceral pericardium
2.2.2.1.3. endocardium
2.2.2.2. specialized junctions
2.2.2.2.1. intercalated discs
2.2.2.2.2. gap junctions
2.2.2.2.3. desmosomes
2.3. contraction
2.3.1. involuntary movement
2.3.1.1. pacemaker cell
2.3.1.1.1. connected to other cells
2.3.1.1.2. control contraction
2.3.1.2. nervous system sends signal
2.3.1.3. speed up or slow down
2.3.1.4. creates heartbeat
2.3.2. autonomous nervous system
2.3.2.1. sarcoplasmic reticulum release Ca2+
2.3.2.2. Ca2+ affect troponin releasing tropomyosin
2.3.2.3. tropomyosin shifts position and myosin attach to actin
2.4. cardiomyopathy
2.4.1. condition that affect cardiac muscles
2.4.2. Hypertrophic cardiomyopathy
2.4.2.1. cardiac muscles enlarge and thicken
2.4.3. Dilated cardiomyopathy
2.4.3.1. ventricles become larger and weaker
2.4.4. Restrictive cardiomyopathy
2.4.4.1. prevents ventricles from filling to their full volume
2.4.5. Arrhythmogenic right ventricular dysplasia
2.4.5.1. cardiac muscle tissue of right ventricle is replaced with fatty or fiber-rich tissue
2.4.6. prevention
2.4.6.1. exercise
2.4.6.1.1. lower blood pressure
2.4.6.1.2. recharge heart rate
3. Smooth Muscle
3.1. functional anatomy
3.1.1. non-striated muscle
3.1.2. involuntary muscle
3.1.3. long fusiform in bundles or fasciculi
3.2. type of smooth muscles
3.2.1. single unit
3.2.1.1. visceral smooth muscle
3.2.1.2. contract rhythmically
3.2.1.3. electrically coupled to one another via gap junctions
3.2.1.4. often exhibit spontaneous action potentials
3.2.1.5. arranged in opposing sheets & exhibit stress-relaxation response
3.2.1.6. present in hollow viscera like:
3.2.1.6.1. uterus
3.2.1.6.2. ureter
3.2.1.6.3. urinary bladder
3.2.1.6.4. respiratory tract
3.2.1.6.5. gastrointestinal
3.2.2. multi unit
3.2.2.1. made up of multiple units without interconnecting bridges
3.2.2.2. location
3.2.2.2.1. blood vessels
3.2.2.2.2. epididymis
3.2.2.2.3. iris
3.2.2.2.4. ciliary body
3.2.2.2.5. piloerector muscle
3.2.2.3. characteristics
3.2.2.3.1. rare gap junctions
3.2.2.3.2. infrequently spontaneous depolarizations
3.2.2.3.3. a rich nerve supply
3.2.2.3.4. structurally independent muscle fibers
3.3. innervation of smooth muscle
3.3.1. lacks neuromuscular junction
3.3.2. innervating nerves have bulbous swellings called varicosities
3.3.2.1. release neurotransmitters into diffuse junction
3.4. proportion & organization of myfilaments
3.4.1. thick filaments have heads along their entire length
3.4.2. no troponin complex
3.4.3. thick & thin filaments are arranged diagonally
3.4.3.1. causes to contract in a corkscrew manner
3.5. contraction of smooth muscle
3.5.1. synchronized contraction
3.5.2. contract in unison
3.5.3. action potential are transmitted from cell to cell
3.5.4. contraction mechanism
3.5.4.1. actin & myosin interact according to the sliding filament mechanism
3.5.4.2. final trigger for contraction is rise in intracellular Ca2+
3.5.4.3. Ca2+ is released from the SR & extracellular space
3.5.4.4. Ca2+ interacts with calmodulin & myosin light chain kinase to activate myosin
3.5.5. special features
3.5.5.1. smooth muscle tone
3.5.5.2. slow, prolonged contractile activity
3.5.5.3. low energy requirements
3.6. role of calcium ion (Ca2+)
3.6.1. binds to calmodulin & activates it
3.6.2. activated calmodulin activates the kinase enzyme
3.6.3. activated kinase transfers phosphate from ATP to myosin cross bridges
3.6.4. phosphorylated cross bridges interact with action
3.6.4.1. to produce shortening
3.6.5. smooth muscle relaxes when intracellular Ca2+ levels drop
3.7. response to stretch
3.7.1. smooth muscle exhibit a phenomenon called stress-relaxation response
3.7.1.1. smooth muscle responds to stretch only briefly & then adapts to its new length
3.7.1.2. the new length retains its ability to contract
3.7.1.3. enables organ to temporarily store contents
3.7.1.3.1. stomach
3.7.1.3.2. bladder
4. Skeletal Muscle
4.1. Characteristic
4.1.1. Voluntary control
4.1.1.1. direct conscious control of the cerebral cortex of the brain
4.1.2. Striated
4.1.2.1. regular arrangement of contractile proteins
4.1.2.1.1. actin
4.1.2.1.2. myosin
4.1.2.2. regular arrangement of contractile proteins
4.1.2.2.1. Actin
4.1.2.2.2. Myosin
4.1.3. Not branch
4.1.4. Multinucleated
4.1.4.1. fusion of the many myoblasts that fuse to form each long muscle fiber
4.1.4.2. Long
4.1.4.3. Unbranched cylinder
4.2. Function
4.2.1. intrinsic excitation-contraction coupling process
4.2.1.1. contraction of the muscle leads to movement of bone that allows for the performance of specific movements
4.2.2. provides structural support and helps in maintaining the posture of the body
4.2.3. acts as a storage source for amino acids
4.2.3.1. used by different organs of the body for synthesizing the organ-specific proteins
4.2.4. maintaining thermostasis and acts as an energy source during starvation
4.3. Types
4.3.1. Parallel
4.3.1.1. A muscle with a common point of attachment, with fascicles running parallel to each other
4.3.1.1.1. fusiform
4.3.1.1.2. non-fusiform
4.3.2. Circular
4.3.2.1. A ring like band of muscle that surrounds a bodily opening, constricting and relaxing to control flow
4.3.2.1.1. Eg : orbicularis oris -->controls the opening of the mouth
4.3.3. Pennate
4.3.3.1. A feather shaped muscle with fascicles that attach obliquely (at an angle) to a central tendon
4.3.3.1.1. Unipennate
4.3.3.1.2. Bipennate
4.3.3.1.3. Multipennate
4.3.4. Convergent
4.3.4.1. A muscle with a common point of attachment, although individual fascicles do not necessarily run parallel to each other
4.3.4.1.1. Eg : pectoralis major -->responsible for flexing the upper arm
4.4. Muscle Fibre
4.4.1. Sarcolemma
4.4.1.1. T- tubules - Rapid Action Potential transmission
4.4.2. Sarcoplasmic Reticulum
4.4.2.1. Termina Cisternae - SR Ca ATPase - Ca2+ into SR
4.4.3. Sarcoplasm
4.5. Myofibril
4.5.1. Repeating sarcomere units
4.5.1.1. Z- Lines - myosin + actin
4.5.2. Shorten in contraction
4.5.2.1. Isotonic - contract + shortens --> move load
4.5.2.2. Contraction - Myosin heads form cross bridges with actin. --> ATP
4.5.2.2.1. Tension ∝ No. Cross bridges
4.5.2.3. Isometric - Contact + NO shortening --> load NOT moved
4.6. Contraction and ATP
4.6.1. Na - K ATPase restores Na+ and K+.
4.6.2. Myosin ATPase (Contraction) and Calcium Pumps
4.6.3. ATP + creatine --> ADP +phosphocreatine CREATINE KINASE
4.6.4. Glycolysis - Very fast, Anaerobic or Aerobic
4.7. Control of contraction
4.7.1. 1. Neuromuscular Junction
4.7.1.1. Somatic motor neurone --> Acetylcholine - Bind --> nicotinic cholinergenic receptor.
4.7.1.1.1. Influx of Na+ = End plate potential
4.7.2. 2. Excitation-Contraction coupling
4.7.2.1. Action Potential --> sarcolemma - t tubules = Ca2+ realease - SR
4.7.2.1.1. Ca2+ -->troponin = free actin binding site - Cross bridges
4.7.2.2. Timing - 1 Relax/Contract Cycle = Twitch
4.7.2.2.1. Twitch --> 2nd AP = latent period ( - biochemical processes)
4.8. Factors affecting contraction force.
4.8.1. Length - Tension
4.8.1.1. Optimum overlap - Z lines not too close/ far apart before contraction.
4.8.2. Summation
4.8.2.1. Close stimuli - Relax failure = summation - Tetanus (Prolonged Contraction)
4.9. Motor Unit
4.9.1. Muscle fibres + Somatic motor neurone
4.9.2. All -or- Nothing contraction
4.9.3. Graded Response - Change No./Type activated units
4.9.3.1. Fine motor e.g Eye - 3 to 5 fibres
4.9.3.2. Gross Motor e.g large muscle - 2000 fibres