Muscular System
Isometric: Muscle contracts but does not move (same length)
Isotonic: Same tension; Subdivides into concentric and eccentric
Concentric: Shortening against resistance
Eccentric: Lengthening against resistance
The inverse relationship between pressure and volume
volume increases, pressure decreases
volume decreases, pressure increases
What are gap junctions, and what do they allow for?
Structures in cardiac muscle that allow for the sharing of action potential between cardiac cells. This allows for the cardiac cells to contract in synch
What is the primary way Oxygen is transported in the blood? What about CO2?
Oxygen: bound to Hb
CO2: Bicarbonate ion
Finish the flow: The muscle is made up of muscle bundles. Muscle bundles are made up of......
Muscle bundles are made up of muscle fibers. Muscle fibers are made up of myofibrils. Myofibrils are made up of sarcomeres
What is surfactant, and why is it important?
An agent produced by the type II alveolar cells that lowers surface tension, so that the pressure across all alveoli that range in size is constant. If the pressure is the same, our lungs can comply with the chest wall, and therefore we maximize the exchange of gases
What is calcium-induced calcium release?
Calcium must enter the cell from the extracellular fluid for calcium to be released from the SR and used in muscle contraction. This mechanism is important so the heart will never go into tetany
What are the two respiratory centers located in the Pons?
Pneumotastic and Apneustic
Pneumotastic: responsible for the rate and pattern of breathing
Apneustic: responsible for the intensity of breathing
Describe the contraction portion of the excitation-contraction coupling
Calcium released from the SR during excitation binds to Troponin, which causes a conformational change that subsequently moves tropomyosin out of the way, exposing the binding sites on actin for myosin to bind to actin. Myosin binds, and the ADP and Pi come off, resulting in the power stroke. ATP will unbind myosin from actin, hydrolyze into ADP and Pi, and the power stroke can happen again
What is happening at the level of the lungs during a shunt? What is the V/Q ratio, and what is a potential cause?
Shunt: when the lungs are perfused but poorly ventilated, leading to hypoxemia (less O2 in the blood)
V/Q ratio is low
Potential cause: Pulmonary edema- the alveoli are filled with fluid, preventing gas exchange, thus decreasing the amount of oxygenated blood leaving the lungs
The tricuspid valve is prolapse. Where will the blood pool?
Right atrium
What are the two protective mechanisms we have in skeletal muscle?
Muscle spindles: monitor muscle length
Golgi tendon organ: monitors muscle tension
How do we get calcium into the cell for muscle contraction?
1. Alpha motor neuron gets stimulated and releases ACH
2. ACH binds to the nicotinic receptor on skeletal muscle, which causes the muscle fiber to reach threshold and elicit an action potential
3. The action potential travels down the t-tubules. The DHP voltage sensor detects the voltage pulls on the Ryniadine receptor which is a gate for SR
4. the gate opens and calcium can enter
What is happening at the level of the lungs in a VQ mismatch? What is the V/Q ratio? What is a potential cause? Will inhaling 100% O2 help?
Yes, inhaling 100% O2 increases the pressure of oxygen, increasing the pressure gradient for O2 to flow into the RBC
What are the 3 phases of systole? Which valves are open in each phase?
Isovolumic contraction period- both valves are closed
Rapid ejection period- aortic valve is open
Slow ejection period- aortic valve is open
What are the two congenital heart defects that result in hypoxemia?
Atrial septal and ventricular septal defect
As we age, the sarcoplasmic reticulum becomes compromised. How would this impact our ability to generate muscle force?
The sarcoplasmic reticulum is responsible for the storage and release of calcium. Calcium is critical for our contractile proteins (actin/myosin) to interact. If our SR is compromised, we ultimately compromise our ability to release Ca2+ and therefore impact the ability for cross-bridge formation- muscle contraction
Carbon monoxide poisoning leads to hypoxia. Explain why. Hint: Carbon monoxide binds to the iron molecule in Hemoglobin
Carbon monoxide binds to the Hb, preventing oxygen from binding, which subsequently affects the delivery of oxygen to our tissues
If the ventricles are contracting asynchronously, where is the problem?
There is an electrical conduction problem as the impulse travels to the bundle branches or the Purkinje fibers
Finish the flow: Epinephrine binds to the beta 1 receptor on the heart......
which stimulates a G protein that stimulates adenylyl cyclase to convert ATP to cAMP