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What is excitation-contraction coupling?
Excitatioin-contraction coupling is the ACTION of RELEASING a NEUROTRANSMITTER at a MUSCLE CELL which INDIRECTLY leads to the CONTRACTION of that cell.
What are the 7 steps of exciation-contraction coupling?
1. ACh is RELEASED from AXON TERMINAL of MOTOR NEURON & BINDS to RECEPTORS in MOTOR END PLATE. This BINDING ELICITS an END-PLATE POTENTIAL which TRIGGERS an ACTION POTENTIAL in the MUSCLE CELL.

2. ACTION POTENTIAL PROPAGATES along the SARCOLEMMA & DOWN T-TUBULES.

3. ACTION POTENTIAL TRIGGERS CALCIUM RELEASE from SARCOLEMMA RETICULUM.

4. CALCIUM BINDS to TROPONIN, EXPOSING MYOSIN-BINDING SITES.

5.CROSSBRIDGE CYCLE BEGINS (muscle fibers contract)

6. CALCIUM is ACTIVELY TRANSPORTED back into LUMEN of SARCOPLASMIC RETICULUM following the ACTION POTENTIAL.

7. TROPOMYOSIN BLOCKS MYOSIN-BINDING SITES (muscle fiber relaxes).











What are the 8 steps of ELECTRICAL CONDUCTION SYSTEM?
1. SA-node cells PRODUCE ACTION POTENTIALS SPONTANEOUSLY about 72 times per minute.

2. ACTION POTENTIAL spreads from SA-NODE 1st to CONDUCTION FIBERS, then to ATRIAL CARDIAC CELLS via GAP JUNCTIONS.

3. IMPULSES spread through ATRIAL TISSUE, DEPOLARIZING them.

4. ATRIA CONTRACT.

5. DEPOLARIZATION WAVE also SPREADS to AV-NODE in BOTTOM of RIGHT ATRIUM

6. IMPULSES SPREAD DOWN to AV BUNDLE and BUNDLE BRANCHES to PURKINJE FIBERS within the VENTRICLES.

7. PURKINJE FIBERS ACT to SPREAD IMPULSES to VENTRICLE MUSCLE TISSUE where GAP JUNCTIONS ELECTRICALLY CONNECT all TISSUES TOGETHER.

8. VENTRICULAR TISSUE CONTRACTS.













What is CARDIAC CYCLE? & What are the 2 SUBDIVISIONS?
TIME from ONSET of 1 CONTRACTILE CYCLE to the ONSET of NEXT CONTRACTILE CYCLE.

DIASTOLE-period of relaxation (.5 sec)
SYSTOLE-period of contraction (.3 sec)


CONTROL OF CARDIAC OUTPUT?
extrinsic/intrinsic?
ALTER either HEART RATE &/OR STROKE VOLUME.

EXTRINSIC & INTRINSIC REGULATION

EXTRINSIC-neural & hormonal
INTRINSIC-autoregulation




Relationship of fluid flow, fluid pressure & resistance.

WHAT IS FLOW, PRESSURE, & RESISTANCE? EQUATION?

Flow occurs from HIGH PRESSURE AREA to LOW PRESSURE AREA

Pressure is the FORCE EXERTED by BLOOD on WALLS of VESSELS

Resistance are ALL FACTORS that IMPEDE the FLOW of FLUID THROUGH VESSELS

EQUATION= FLOW=PRESSURE/RESISTANCE





Relationship of fluid flow, fluid pressure & resistance.

WHAT 2 THINGS DOES THE EQUATION FLOW=PRESSURE/RESISTANCE say?

1. Flow & pressure are PROPORTIONAL to ONE ANOTHER.

2. FLOW & RESISTANCE are INVERSELY PROPORTIONAL TO ANOTHER

*as pressure increases, flow will increase.



3 factors affecting resistance to flow
1. radius of vessel
-in arterioles & small artiers can regulate radius
-changes have 4th power effect (small change in vessel radius will have large change in resistance)

2. length of vessel(s)

3. viscosity of fluid in vessels
-blood viscosity dependent on amount of RBCs & proteins






What is the blood flow equation?
B.F.=B.p. x VESSEL DIAMATER^4/VESSEL LENGTH x BLOOD VISCOSITY
pressure gradients & resistance in systemic circulation

what would flow pressure resistant be? & cardiac output?

FLOW=PRESSURE/RESISTANCE

FLOW=C.O.
PRESSURE=M.A.P.
RESISTANCE=T.P.R.

C.O.=M.A.P./T.P.R.

arterioles provide greatest resistance to B.F. & most regulation of B.F.







regulation of resistances and blood flow
B.P.=B.F. x R

any increase in either B.F. &/or R will increase B.P. & vice versa

blood pressure determination
B.P. is show as systolic pressure/diastolic pressure



what is pulse pressure?
Systolic pressure subtract diastolic pressure
Equation of M.A.P.
M.A.P.=(S.P. + (2 x D.P.)/3
what is pulmonary ventilation?
movement of air into and out of alveoli due to air pressure gradients created by changes in thoracic volume
what is atmospheric pressure?
760mmhg
pulmonary vent.

When pressure in alveoli is less than 760mmhg, then.....

When pressure in alveoli is greater than 760mmhg, then....



-air moves INTO alveoli

-air moves out

pulmonary vent.

what is boyles law?

as volume of area increases, pressure in that area decreases
control of ventilation by chemoreceptors: what are the 2 types?
1. central found in medulla
2. peripheral found in carotids
what is PERipHERAL CHEMORECEPTORS?
-responds primarly to blood ph
-as blood CO2 changes, ph changes
-increase CO2 decreases ph & vice versa

-will only respond to changes in arterial blood PO2 but only if it drops below 60 (100 is normal) thus O2 levels are not normally a cause for changes in respiration



what are CENTRAL chemoreceptors?
located in medulla

-responds to chantes in ph of cerebralspinal fluid

-not responsive to changes in PO2



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