Exam 2 Flashcards
Muscle Classifications
Skeletal Muscle
Smooth Muscle
Cardiac Muscle
Myocyte
Muscle Cell
Sarcomere
Individual contractile unit in skeletal muscle
Sarcolemna
Plasma membrane of skeletal muscle cells
Myrofibrils
Give structure to muscle cells through thin actin filaments and thick myosin filaments
Epimysium
Connective tissue sheath that encases the entire muscle (skeletal)
Perinmysium
Surrounds muscle bundle (skeletal)
Endomysium
Surrounds myoctes (skeletal)
What is skeletal muscle in between?
2 Z lines
sarcoplasmic reticulum
smooth ER (skeletal)
stores calcium
stores glycogen
Capacity of mitochondria in skeletal muscle
Contains many mitochondria
Misconception about contraction of muscle
A common misconception is that muscle shortens when contracted
How does contraction occur (simply)?
Through the sliding of thick Myosin filaments and thin Actin filaments
What is the result of bases in contraction?
Shortens Distance of Z-lines and all bands except for the A band
Tropomyesin
blocks the binding cite on actin for myosin and inhibit interaction when relaxed
Properties of Myosin
2 Heavy Chains and 4 Light chains
Troponins
Part of Actin
Troponin C
Troponin I
Troponin T
Troponin C
binds calcium
Troponin I
Binds Actin
Troponin T
Tropomyesin
Relaxation of Skeletal Muscle
Low Cytoplasmic Ca
Myosin head is energized through ADP + Pi bound to the head
Cross Bridge Cycle Purpose
Contraction of muscle
Steps of Cross Bridge Cycle
1.) Low Ca
2.) Energized myosin head (ADP + Pi)
3.) Releases Ca from sarcoplasmic reticulum(Goes from 10^-7 M to 10^-5 M)
4.) Ca binds to troponin C
5.) Open actin binding cites
6.) Myosin binds to actin
7.) ADP + Pi come off of myosin and allows for myosin to move
8.) ATP binds to myosin and allows for myosin to release from actin
9.) ATP goes back to ADP + Pi which then in turn renergizes myosin head
What triggers a new Cross Bridge Cycle
High amounts of Ca and the renewal of ATP in (ADP and Pi)
What receptor is part of the sarcoplasmic reticulum and what is it responsible for?
The ryadine receptor is a calcium channel that connects to a neuromuscular junction
Motor Unit
Motor neuron and skeletal muscle fibers it innervates
Motor neuron rates of connection
1 motor neuron innervates many muscle fibers however one muscle fiber is innervated by only one motor neuron
Within a whole muscle are there many motor units or few?
many
What is a neuromusclular junction
Its the interaction between the skeletal muscle and axon terminus
Motor end plate
Region of post synaptic membrane
Whats the ratio of neuromuscular cell to neuromuscular junction?
1:1
Traverse tublues
Contains the DHP receptor
DHP receptor
Part of the neuromuscular junction of the transverse tubules and it is a volted gated calcium channel that is connected to the Sarcoplasmic reticulum
What do neuromuscular vesicles contain?
Acetyl Choline
What is the relationship between the relative refractory period and the pumping of calcium
The speed of pumping calcium into the sarcoplasmic reticulum is slower than the refractory period
What happens as soon as calcium is released
it’s pumped back to SR
What does smooth muscle not have in comparison to skeletal?
Transverse tubules
Troponins
neuromuscular junction
What does smooth muscle have instead of troponins
varicosities
What are the two types of smooth muscle?
Multi unit and single unit
Multi Unit Smooth Muscle Loc.
In walls of large arteries and upper large airways in lung
Single Unit Smooth Muscle(loc)
In digestive tract, in walls of uterus, contains gap junctions
What is spontaneous activity known as as part of a neurotransmitter in smooth muscle?
Myogenic activity
How does contraction in smooth muscle
its a calcium mediated event that comes out of cell and binds to calmodulm instead of troponin C
What does calmodulm activate?
Activates myosin light chain kinase
How does calcium enter axon terminals?
Through voltage gated calcium channels (DHP receptors)
What does calcium trigger the release of from axon terminals?
Acetyl Choline
Where does acetyl choline diffuse in muscle fiber?
From axon terminals to moter end plates
Where does acetyl choline bind to and what does this then allow?
It binds to nicotonic receptors on the motor end plate which then increases the permeability of sodium and potassium
Where does end plate action potential travel along?
T-Tubules
What’s the purpose of calcium binding to troponin on thin filaments?
Causes tropomyesin to move away from its blocking position and thereby help start the crossbridge cycle
How does the action potential across T-tubules induce travel of calcium
DHP receptors pull open and allow the release of Calcium from the sarcoplasmic reticulum
What form of energy is used for thick filaments to bind to actin?
ADP
What breaks down the linkages between myosin and actin?
ATP
What energies the myosin crossbridge
ATP –> ADP
What does the cycle of the cross bridge cycle induce?
The sliding of actin and myosin
Where does calcium go after the cross bridge cycle is complete?
The sarcoplasmic reticulum
What happens as soon as calcium is removed from troponin?
Restores the blocking action of tropomyesin on actin and allows muscle fibers to relax
Cardiomyocytes physical components
Involuntary striated muscle
More stellated
branches
fibrous cards
How many nuclei are present in cardiomyocytes?
1 or two nuclei
Whats very similar between cardiomyocytes and skeletal muscle
The cross bridge cycle
Cell to Cell grouping in cardiomyoctyes
contain gap junctions and are intercalated discs
What determines the rate of depolarization in cardiomyocytes?
Population of cells with most unstable resting potential
Describe the refactory period of cardiomyocytes
It’s protracted and causes obigatory relaxation of cardiac muscle
What does the excitation/depolarization of skeletal muscle or cardiomyocytes allow for?
The opening of T-tubules and Calcium channels
Pericardium Structure
Contains serous fluid
Parietal (Outer)
Visceral(Inner)
Myocardium
True Heart Muscle
Endocardium
Endothelial cells continuous with blood cells
Atria
Receive Venous Blood
Ventricles
Much Thicker walls
pump blood throughout body
Atrio-ventricular Left and Right differences
Right AV is tricuspid, Left is bicuspid
Chordae Tendinae
Anchor free margin of valve
Papillory
Anchors chordae tendinae
Semi-lunar (Heart) Left and Right
Trans-cuspid
Separate ventricles and arteries
Right: Right ventricle and pulmonary artery
Left: Left ventricle and aorta
Sinoatrial node
Pacemaker (Responsible for heartbeat)
Atrioventricular Node
Promotes healthy conduction pathways in heart
Bundle of HIS
Branches from antrioventricular node
branches from left and right bundles
Purkenji Fibers
conduct electrical stimulus
SA node stabilization
acetyl choline via muscarnic receptors which then stabilizes the node
Norepenephrine via adrenergic receptors
increases contraction
Pathway of Circulation
Vena cava –> RA –> Tricuspid Valve –> RV –> Pulmonary Valve –> Pulmonary A –> Lungs –> Pulmonary Veins –> LA –> Mitral Valve –> LV –> Aortic Valve –> Aorta
Diastole
Ventricles are relaxed, fills blood
Systole
Ventricles are contracted, pushes out blood
Lubb
Closure of Atrioventricular valves (tricuspid/bicuspid)
Dupp
Closure of Semilunar valves (Aortic/pulmonary)
Types of Murmurs
Stenosis and Insufficieny
Stenosis
The valve is stiff, doesn’t totally open, in diastole its heard in the atrioventricular, during semilunar its systolic
Insufficiency
Not closing completely, back flow, AV = systolic, semilunar = diastolic
What changes in the heart during a contraction cycle
Pressure and Volume
What does cardiac output = to
Heart Rate * Stroke Volume
What’s normally the ratio of increasing heart rate or stroke volume?
Both will increase when increasing one
Steps of Regulation for the heart
Increase in atrial pressure –> Baroreceptors –> Afferent nerve endings –> medulla–> efferent nerve endings –> Heart
Baroreceptors
Sensory nerve endings, detects increase in pressure. Is felt through carotid sims and the left aorta that goes to the brain
Cardioinhibitory Center
In the medulla, Vagal output to SA node, reduces cardiac output
Vasomotor
In the medulla, increases cardiac output through speeding up the tachycardia with epinephrine
Starlings law of the heart
Strength of contraction during systole is proportional to ventricular distension at the end of the diastole
What neurotransmitters increase and decrease HR
Norep. inc.
Acetyl Choline dec.
What will happen if you increases the sympathetic output of norep
Increases the strength of contraction which will then increase stroke volume
Properties of Major Arteries
Fibrolastic Walls
Allows stretch and recoil
Less Neural Control
Arterioles Properities
Tunic Media
Less Stretch and Recoil
Sympathetic Output
Tunic Media
Smooth muscle layer in Arterioles
Sympathetic Output in Arterioles
Causes waves of constriction (made of endothelial cells)
Is blood pressure greater or lesser in the pulmonary in comparison to systemic?
Pulmonary Pressure is less than systemic circulation
In response to pulsation contraction of the heart:
Pulses of pressure move throughout the vasculature, decreasing in amplitutde with distance.
Tonic wave of constriction
A tone provided to constricted or non constricted valves
Major drop in systemic blood pressure occurs in ….
arteries
What regulates downstream pressures and flow rates?
Dynamic changes in vasodilation and vasoconstriction