Exam 3 Flashcards
Muscle Cell/ Muscle Fiber
A cell that has differentiated for the specialized function of contraction
Functions of the muscular system
Heat, Movement, Posture, Structure
Myofibril
The long thin contracting protein subunits of a muscle cell that are composed of actin and myosin filaments.
Thick Filament
Myosin, essentially a molecule with 2 round heads and chain-like tail.
Thin Filament
A polymer of actin with tightly bound regulatory proteins troponin and tropomyosin
function and location of myosin heads
Function: Bind and hydrolyze ATP,
Location: attached to elongated tail region
Function and location of myosin head binding sites
Function: Facilates binding so cross-bridges can form
Location: on the actin filaments
Function and location of actin
Function: Shortens the sarcomere
Location: attached at their plus ends to the Z disc
Function and location of troponin
function: sarcomeric Ca2+ regulator
location: attached to the protein tropomyosin and lies within the groove between actin filaments
Function and location of tropomyosin
Function: Stabilizes actin filaments but also regulates muscle contraction
Location: in each of the two long-pitch helical grooves of actin
Function and location of Ca2+
Function: induces skeletal muscle contraction
Location: the cytosol
Sliding filament model of contraction
Within the sarcomere, myosin slides along actin to contract the muscle fiber in a process that requires ATP.
Excitation-contraction coupling
The rapid communication between electrical events occurring in the plasma membrane of skeletal muscle fibres and Ca2+ release from the SR, which leads to contraction
Steps in the process of excitation-contraction coupling
Step 1
Action potential spread along the sarcolemma to the T-tubules (transverse tubules)
Step 2
Calcium is released into the sarcoplasmic reticulum (S.R.)
Step 3
Calcium binds to actin and the blocking action of the tropomyosin is removed
Step 4
Myosin heads attach to begin contraction
Step 5
Calcium is removed and the binding sites on actin become blocked again by tropomyosin
Step 6
Muscle relaxes
Steps in cross bridge cycling, and the involvement of ATP, cross bridges, and the myosin head ATPase
Step 1
cross bridge formation: phosphorylated myosin head attaches to an actin myofilament
Step 2
the power stroke:
1) ADP and Pi are released from the myosin head
2) Myosin head changes to bend, low-energy state
3) Shape change pulls the actin towards the M line
Step 3
cross bridge detachment: ATP attaches to myosin, breaking the cross bridge
Step 4
cocking of the myosin head: attached ADP is hydrolyzed by myosin ATPase into ADP + Pi, bringing it back to a high-energy state
How a muscle cell obtains the ATP it needs
Using creatine phosphate
Using glycogen (no oxygen)
Using aerobic respiration
isotonic Contractions
Tension remains the same in the contraction
concentric contractions
total length of the muscle shortens as tension is produced
eccentric contractions
total length of the muscle lengthens as tension is produced
isometric contractions
Length remains the same, but tension changes
main steps in hemostasis
(1) vascular spasm, or vasoconstriction, a brief and intense contraction of blood vessels; (2) formation of a platelet plug; and (3) blood clotting or coagulation
Thrombus
A blood clot that forms inside one of your veins or arteries
Embolus
An unattached mass that travels through the bloodstream and is capable of creating blockages
Universal donor
Universal donors are those with an O negative blood type.
Universal recipient
a person of blood group AB, who can in theory receive donated blood of any ABO blood group
functions of the cardiovascular system
Transport blood and O2
main parts of the cardiovascular system
heart, Arteries, veins, capillaries, and blood
the flow of blood through the parts of the cardiovascular system
Blood—-> right atrium—–> tricuspid v. —-> right ventricle——> pulmonary arteries —–> Pulmonary veins—–> heart——->left atrium—-> mitral valve——> left ventricle——> Aortic v. ——> Aorta—–> body tissues
the attachment of the pulmonary and systemic circulation to the heart
Pulmonary circulation moves blood between the heart and the lungs. It transports deoxygenated blood to the lungs to absorb oxygen and release carbon dioxide. The oxygenated blood then flows back to the heart. Systemic circulation moves blood between the heart and the rest of the body.
unique features of cardiac muscle tissue that allow it to perform its functions.
Intercalated discs, gap junctions
how electrical impulses travel through the heart
Atrial depolarisation
Ventricular depolarisation
Atrial and ventricular repolarisation.
The electrical impulse travels from the sinus node to the atrioventricular node (also called AV node). There, impulses are slowed down for a very short period, then continue down the conduction pathway via the bundle of His into the ventricles
The steps in the cardiac cycle
Atrial Diastole: In this stage, chambers of the heart are calmed. That is when the aortic valve and pulmonary artery closes and atrioventricular valves open, thus causing chambers of the heart to relax.
Atrial Systole: At this phase, blood cells flow from atrium to ventricle and at this period, atrium contracts.
Isovolumic Contraction: At this stage, ventricles begin to contract. The atrioventricular valves, valve, and pulmonary artery valves close, but there won’t be any transformation in volume.
Ventricular Ejection: Here ventricles contract and emptying. Pulmonary artery and aortic valve close.
Isovolumic Relaxation: In this phase, no blood enters the ventricles and consequently, pressure decreases, ventricles stop contracting and begin to relax. Now due to the pressure in the aorta – pulmonary artery and aortic valve close.
Ventricular Filling Stage: In this stage, blood flows from atria into the ventricles. It is altogether known as one stage (first and second stage). After that, they are three phases that involve the flow of blood to the pulmonary artery from ventricles.
systole and how long it typically lasts
Contraction of the heart
Lasts: 0.3 to 0.4 second
diastole and how long it typically lasts
Relaxation of the heart
Lasts: 0.5 sec
the typical heart sounds, what produces them, and when they occur with respect to systole, diastole, and the cardiac cycle
s1- “lub”, created by the closing of the atrioventricular valves during ventricular contraction (systole)
s2-“Dub”,sound of the closing of the semilunar valves during ventricular diastole
s3- A galloping sound, sound of blood striking the left ventricle during early diastole
s4- A galloping sound heard in late diastole
Cardiac output
Tthe volume of blood being pumped by a single ventricle of the heart, per unit time
Cardiac rate
The number of times your heart beats per minute.
Stroke Volume
The volume of blood pumped out of the left ventricle of the heart during each systolic cardiac contraction
Typical values for Cardiac output
5-6 L/min in an at-rest to more than 35 L/min in elite athletes during exercise
Typical values for Cardiac rate
60 to 100 beats per minute.
Typical values for stroke volume
50 to 100 ml
End Diastolic volume
the amount of blood that is in the ventricles before the heart contracts
End Systolic Volume
the volume of blood in a ventricle at the end of contraction, or systole, and the beginning of filling, or diastole
Typical values for EDV
70-155 mL
Typical values for ESV
50 and 100 mL
factors influencing blood pressure
Cardiac output.
Peripheral vascular resistance.
Volume of circulating blood.
Viscosity of blood.
Elasticity of vessels walls.
Auscultatory (manual) blood pressure measurement method and how it works
Auscultatory (manual) blood pressure utilizes a sphygmomanometer, a device comprised of an inflatable cuff connected to a pressure gauge (generally a column of mercury). To measure an individual’s blood pressure, the deflated cuff is placed around the arm and inflated sufficiently to occlude arterial flow
primary and secondary hypertension
High blood pressure that doesn’t have a known cause is called essential or primary hypertension. In contrast, secondary hypertension has a known cause.
neuromuscular junction in excitation-contraction coupling
excitation-contraction coupling process begins with signaling from the nervous system at the neuromuscular junction
motor end plate in excitation-contraction coupling
MEPs receive electrical signals from motor neurons, generate endplate potentials, and consequently induce muscle contractions
end plate potential in excitation-contraction coupling
the voltages which cause depolarization of skeletal muscle fibers caused by neurotransmitters binding to the postsynaptic membrane in the neuromuscular junction
muscle-surface voltage-gated Na+ channels in excitation-contraction coupling
The membrane depolarization at the synaptic cleft triggers nearby voltage-gated sodium channels to open.
action potentials in excitation-contraction coupling
excitation-contraction coupling generates the AP to create cardiac muscle contractions
T-tubules in excitation-contraction coupling
rapidly conduct electrical excitation and facilitate communication with the sarcoplasmic reticulum (SR
voltage-sensitive receptors in excitation-contraction coupling
triggering intracellular calcium release for excitation-contraction coupling.
terminal cisternae in excitation-contraction coupling
Helps form the triad
Ca2+ channels in excitation-contraction coupling
opens the Ca2+ release channels in the TC-SR (surface facing the T-tubule).
troponin in excitation-contraction coupling
Troponin binds to Ca2+
tropomyosin in excitation-contraction coupling
covers the myosin binding sites and prevents cross-bridge formation when a muscle is relaxed
actin filaments in excitation-contraction coupling
drawn toward the center of the sarcomere, overlapping the myosin filament
myosin filaments in excitation-contraction coupling
Myosin heads attach to actin
Ca2+ ATPase in excitation-contraction coupling
pumps the calcium back into the SR, lowering the calcium levels and producing muscle relaxation.
the result of applying successive action potentials to a muscle.
Gradual increase in the force generated by that muscle
summation
accumulating contractile force resulting from sequential activations applied to a muscle without sufficient interval to permit complete relaxation
unfused tetanus
when the muscle fibers do not completely relax before the next stimulus because they are being stimulated at a fast rate
complete tetanus
During complete tetanus, there’s no relaxation period between muscle contractions. Your muscle contractions completely fuse to create one continuous muscle contraction.
fatigue
a decrease in maximal force or power production in response to contractile activity
recruitment
process by which different motor units are activated to produce a given level and type of muscle contraction.
factors that influence the force, velocity, and duration of skeletal muscle contraction
muscle fiber type, load and recruitment.
characteristics of slow oxidative, fast oxidative, and fast glycolytic muscle fibers
Type 1: Slow oxidative (SO) fibers contract relatively slowly and use aerobic respiration (oxygen and glucose) to produce ATP. They produce low power contractions over long periods and are slow to fatigue.
Type 2 A: Fast oxidative (FO) fibers have fast contractions and primarily use aerobic respiration, but because they may switch to anaerobic respiration (glycolysis), can fatigue more quickly than SO fibers.
Type 2 B: Fast glycolytic (FG) fibers have fast contractions and primarily use anaerobic glycolysis. The FG fibers fatigue more quickly than the others[3].
the formed elements that exist in blood and the purpose of each
red blood cells (erythrocytes)
purpose: carry oxygen from the lungs and deliver it throughout our body
white blood cells (leukocytes)
purpose: help the body fight infection and other diseases
platelets (thrombocytes)
Purpose:to prevent and stop bleeding
