PHSL EXAM 2

Discuss how neural (baroreceptors) and hormonal (RAAS) mechanisms work together to maintain BP. Explain the functions of aldosterone and angiotensin II.

Angiotensin II- vasoconstrictor. Increases Vascular resistance. Increases BP/ hydrostatic pressure Aldosterone- Hormone that works through the kidney. Increases plasma volume. Increases BP/hydrostatic pressure RAAS mechanism works to raise BP/hydrostatic pressure -Low BP causes renin release from kidney -Angiotensinogen is converted to angiotensin -Angiotensin I in converted to Angiotensin II -ACE- Angiotensin converting Enzyme -Vasoconstriction and aldosterone release -Aldosterone increases plasma volume Baroreceptors -Negative feedback control loop that regulates BP if it gets too high or too low

Describe the three layers of vessels (connective tissue for strength and elastance), smooth muscle for regulating of the radius size and endothelium for a smooth lining) and apply characteristics of the layers to the function of a given vessel. For example the aorta has mostly connective tissue, helping it to stretch and spring back during the cardiac cycle. This connective tissue also helps the aorta withstand the high pressure, high velocity blood flow exiting the left ventricle. Repeat this thought process for arterioles, capillaries and veins.

Aorta: the aorta has mostly connective tissue, helping it to stretch and spring back during the cardiac cycle. This connective tissue also helps the aorta withstand the high pressure, high velocity blood flow exiting the left ventricle. Arterioles:

List in sequence the steps involved in neuromuscular transmission for skeletal muscle and point out the location of each step on a diagram of the neuromuscular junction; name the neurotransmitter and describe three ways the neurotransmitter molecules in the synaptic cleft are removed after the nerve stops sending signals. (Chapter 11.3, Fig. 10.11)

Before a skeletal muscle fiber can contract, it must be stimulated by a somatic motor neurons. Neuromuscular junction (NMJ) is the synapse between a somatic motor neuron and a skeletal muscle. NMJ has three main parts: presynaptic terminal, motor end plate, and synaptic cleft. 1. Somatic motor neuron action potential 2. Calcium enters votage gated channels 3. Acetylcholine is released 4. Acetylcholine binding to ACh receptor on motor end plate 5. Allows Na+ influx ( and K+ efflux, making Na+ influx greater) 6.Depolarizes membrane, creating end plate potential (EPP) normally always reaches threshold and initiates action potential 7. Sequential opening of voltage gated Na+ channels lets action potential travel to t-tubules (slower than AP of axons but similar)

Describe the relationship between blood flow, mean arterial pressure and vascular resistance (Ohm's Law).

Blood flow (Q) and pressure are proportional and resistance is not proportional.

Calculate the CO from the product of HR and SV. Note that SV = EDV - ESV. Students should know this formula. Students should know that an average CO is 5 L/min.

Heart Rate X Stroke Volume = Cardiac Output

Discuss the mechanical and electrical events of the cardiac cycle during diastole and systole from the Cardiac Cycle Diagram. Not only should student follow each graph, sounds, ECG, volume curve, pressure curve, etc. they should also be able to move up and down the diagram from curve to curve. For example, after the P wave, one should see an increase in atrial pressure as a result of atrial contraction. This diagram will be provided on the exam. Don't memorize it; learn how to work through it.

Diastole= relaxation Systole= contraction Electrical/Mechanical P Wave: atrial depolarization / atrial contraction QRS complex: ventricular depolarization / ventricular contraction (systole) T Wave: ventricular repolarization / ventricular relaxation (diastole)

Relate principles of negative feedback to blood pressure regulation. Blood pressure regulation is one of the most important negative feedback mechanisms in the body.

Increased blood volume causes increased BP. Triggers decreased cardiac output and vasodilation, also increase in fluid excreted by kidneys so BP will go down. If blood pressure is too high, the heart rate decreases as the blood vessels increase in diameter ( vasodilation ), while the kidneys retain less water.

Give an overview of the function of the organelles (T-tubules, sarcoplasmic reticulum, contractile apparatus) and proteins (voltage-gated Ca2+ channels and SR calcium release channels) that are responsible for excitation-contraction coupling in cardiac muscle (i.e. calcium induced calcium release). Remember that you have encountered some of these proteins in neurons and skeletal muscle cells. Build on your previous knowledge.

Excitation-contraction coupling in the cardiac muscle begins when the cardiac muscle action potential travels along the sarcolemma and into the T-tubules, where the voltage-gated Ca 2+ channels (dihydropyridine receptors) open. The entering Ca 2+ functions as a trigger Ca 2+ that binds to and opens the Ca 2+ release channels in the SR membrane. Then Ca 2+ enters the sarcoplasm from the SR. The process where the extracellular Ca 2+ triggers the release of the stored Ca 2+ from the sarcoplasmic reticulum is the Ca 2+ induced Ca 2+ release (CICR). The increase of Ca 2+ concentration in the sarcoplasm starts the muscle contraction. After the Ca 2+ concentration in the sarcoplasm increases, the Ca 2+ binds to troponin, moving the tropomyosin away from the myosin-binding sites on actin and the thin and thick filaments begin to slide past one another. Contraction of cardiac muscle fibers ends when Ca 2+ concentration in the sarcoplasm decreases to resting levels. This occurs by the Ca2+ATPase pump (pump Ca 2+ back onto the sarcoplasm against its concentration gradient) and the Na+-Ca2+ exchangers in the sarcolemma that actively transport Ca2+ out of the cell in exchange for Na +.

List the potential sources of calcium that contribute to smooth muscle activation. (Chapter 11.8, Fig. 30)

-voltage gated channels -calcium release channels -receptor-activated channels -IP3-gated channels -store-operated channels -mechanically gated channels

Use your knowledge of the flow of blood through the heart to explain the operation of the valves and the events of the cardiac cycle. Explain mechanism of valve opening/closing. Explain the importance of pressure gradients for valves to open and close.

1. Deoxygenated blood enters the heart through the right atrium. 2. Atrium pumps blood flow through the right AV valve (tricuspid) in the right ventricle, which pumps the blood into the pulmonary artery 3. Pulmonary artery carries deox. blood to lungs and blood becomes oxygenated. 4. Oxygenated blood is carried to the left atrium 5. Oxygenated blood blasses to the left ventricle which pumps blood into the aorta. 6. Aorta delivers blood to the rest of the body All 4 valves: -can be closed @ same time -are never open @ same time -only 2 sets of valves open @ same time

Diagram the chemical and mechanical steps in the cross-bridge cycle, and explain how the cross- bridge cycle results in shortening of the muscle. (Chapter 11.3, Fig. 11.8)

ATP hydrolysis: A myosin head includes an ATP-binding site that functions as an ATPase (an enzyme that hydrolyzes ATP into ADP). The energy generated from this hydrolysis reaction is stored in the myosin head and used later in the contraction cycle. The myosin head is energized and perpendicular to the thin filament to bind to an actin molecule. ADP and a phosphate group are still attached to the myosin head. Attachment of myosin to actin: The energized myosin head attaches to the binding site on the actin and the phosphate group is released. When the myosin head is attached to the actin during the contraction cycle, the myosin head is referred to as a cross bridge. Power stroke: After the cross-bridge forms, the myosin heads pivot, pulling the thin filament (actin) towards the center of the sarcomere. This is known as a power stroke. The energy required for a power stroke is from the energy stored in the myosin head from the hydrolysis of ATP. When the power stroke occurs, ADP is released from the myosin head. Detachment of myosin from actin: The cross-bridge remains attached to the actin until another APT bind. As ATP binds to the ATP-binding site on the myosin head, the myosin head detached from the actin.

Compare and contrast AV node cells and Purkinje fibers. What are the properties that help the AV node bring about AV delay? What are the properties of the Purkinje fibers that help them spread ventricular depolarization quickly and extensively?

AV node: fewer gap junctions. 50-60 BPM Purkinje fibers: fast electrical activity. More # cells. More gap junctions. about 40 BPM.

Distinguish between a single twitch and a tetanic contraction in skeletal muscle and explain why twitch response is smaller in amplitude than a tetanic contraction. (Chapter 11.5, Fig. 11.15)

A twitch is the brief contraction of a group of muscle fibers within a muscle in response to a single action potential. A tetanic contraction is a sustained muscle contraction evoked when the motor nerve that innervates a skeletal muscle emits action potentials at a very high rate. During this state, a motor unit has been maximally stimulated by its motor neuron and remains that way for some time Twitch response is smaller in amplitude than a tetanic contraction because is not influenced by the constant firing of action potentials that continue to increase the tension until the tetanic reaches a plateau level.

Describe the relationship between different degrees of myofilament overlap and the shape of the length-tension relationship. (Chapter 11.5, Fig. 11.16)

Optimal length (2.2 um): the zone of overlap in each sarcomere is optimal, and the muscle fiber can develop maximum tension. Overstretched (3.8 um): As the sarcomeres of the muscles fibers are stretched to a longer length (overstretched), the zone of overlap shortens, and fewer myosin heads can make contact with actin and tension decreases. Understretched (1.8um): As the sarcomere lengths become shorter than the optimal length (understretched), the tension that can develop decreases. Thick filament crumple as they are compressed by the Z discs, resulting in fewer myosin heads making contact with actin filaments. This leading to a decrease in tension.

Describe the parts (receptor, sensory neuron, integrator, motor neuron, effector=target) of the baroreceptor reflex arc.

Respond to changes in blood pressure. Stimulus: drop in BP Receptor: baroreceptor stretches and sends an AP Afferent: sensory neuron receives AP. Send frequency of action potentials based on the amount of depolarization in the baroreceptor. Integrating center: cardio vascular control center. Brain stem medulla receives AP decides what to do with the stimulus about the blood pressure Efferent: motor neurons. ANS Effectors: PNS (SA and AV node) SNS (SA and AV nodes, heart muscle, and vascular smooth muscle. Response: increase in BP

Discuss the dual innervation of the heart and the regulation of HR and SV by ANS. Both the parasympathetic and sympathetic nervous systems innervate the SA node but these two systems have opposite effects on the heart rate. Identify which neurotransmitters are released by each branch. Discuss the mechanism of this modulation of the heart rate by neurotransmitters (i.e. which channels are opened).

SNS- NE -speeds up heart rate, increases depolarization, unstable funny channels - PNS-ACh -slows down heart rate, decrease depolarization, funny channel is less open.

What sets the basic heart rate rhythm? Predict the outcome if all nerves to the SA node were severed.

The SA node of the heart sets the basic heart rate rhythm. If all nerves to the SA node were severed it would still continue to beat because the heart does not require any outside neural stimulus to contract.

Describe arterial pressure changes during the cardiac cycle and how the vascular principle of elastic recoil (also called elastance) permits the vessels (particularly the aorta) to maintain a diastolic pressure.

The aorta is compliant and elastic. Compliance refers to the ability of the blood vessels to stretch because of a change in pressure. Viens have a higher compliance, whereas arteries have a low compliance.

Describe Ca2+ accumulation in the sarcoplasmic reticulum mediated by Ca2+-ATPase. Explain the role that these (Ca2+-ATPase pump proteins) transporters play in muscle function. (Chapter 11.3)

The membrane of the sarcoplasmic reticulum (SR) contains active transport proteins called Ca2+-ATPase that constantly transport Ca 2+ from the sarcoplasm into the SR. While muscle action potentials continue to propagate, the Ca 2+ release channels are open. Ca 2+ flows into the sarcoplasm (moving down its concentration gradient). When Ca 2+ release channels close and Ca 2+-ATPase pumps use ATP to pump Ca 2+ back into the sarcoplasm and restore the low levels of Ca 2+.

Define afterload and discuss situations in which a high afterload could decrease the stroke volume. The opening and closing of the semilunar valves should factor into your answer. Specifically, students should understand that the left ventricle is more muscular than the right ventricle because the left ventricle pumps against 5 times the afterload as compared to the right ventricle.

The pressure that must be overcome before a semilunar valve can open. An increase in afterload causes stroke volume to decrease so that more blood remains in the ventricles at the end of systole. Conditions that can increase afterload include hypertension (elevated blood pressure) and narrowing of arteries by atherosclerosis.

preload

degree of strength on the heart amount of blood before ejection (EDV)

Define contractility

The strength of contraction at any given preload.

contractility

force and intensity of contraction

Factors of cardiac output

heart rate, preload, contractility and afterload.

Describe the function of intercalated discs. Specifically, discuss how gap junctions electrically connect cardiac myocytes and desmosomes physically connect cardiac myocytes. Discuss why this facilitates the myocardium working as a pump (Think functional syncytium = many cells working as one unit).

irregular transverse thickenings of the sarcolemma that connect the ends of the cardiac muscle fiber to one another. These discs contain desmosomes, which hold the fibers together and gap junction, which allows the movement of Ca 2+ ions from one cell to another and allows muscle action potentials to spread through one cardiac muscle to another. unique to cardiac muscle fibers

Compare and contrast the structure, anatomical location, and function of muscle spindles and Golgi tendon organs. (Chapter 12.2, Fig. 12.3, 12.4)

muscle spindles: monitor the length of the muscle. Slight stretching of a muscle stimulates sensory receptors in the muscle called muscle spindles. generates a receptor potential. If the receptor potential reaches threshold, it triggers one or more action potentials that propagate along a somatic sensory neuron through the dorsal root of the spinal nerve and into the spinal cord. Found in extensors (quadriceps) golgi tendon organs:

heart rate

number of beats per minute

afterload

pressure required to eject blood ventricles to aorta (left) or pulmonary artery (right).

Explain how the length of the refractory period prevents tetany in cardiac cells. (HINT: Think about skeletal muscle. The short action potential and long twitch creates a situation where skeletal tetany can occur. What happens to the action potentials in cardiac tissue that prevents tetany in cardiac tissue?)

the refractory period lasts almost as long as the duration of a contraction, due to the prolonged plateau phase in the action potential. This prevents the muscle fiber from being re-excited until its previous contraction is almost over, which prevents tetany in cardiac muscles. the pumping action of the heart depends on alternating contractions and relaxation. If the cardiac cells undergo tetanus, the heart would not be able to function as a pump and not relax and refill with blood.

Cardiac output (CO)

volume of blood ejected from each ventricle of the heart per minute

Describe the flow of depolarization through the conducting pathway,particularly noting how the depolarization starts in the SA node, is slowed at the AV node and then is rapidly transmitted throughout the ventricles by the Purkinje fibers.

(1): A cardiac action potential arises in the SA node and is propagated throughout the atrial muscle down to the AV node. As the atrial contractile fibers begin to depolarize a P-Wave is produced. (2): After the P-Wave begins, the atrial contract (atrial systole). Conduction of the action potential slows at the AV node because the fibers have smaller diameters and fewer gap junctions, leading to the AV nodal delay. The delay gives the atria time to full contract and move the blood from the atria to ventricles before the ventricles start contracting (ventricular systole). (3): The action potential propagates rapidly entering the AV bundle through the Purkinje fibers. The depolarization of the ventricular contractile fibers produces QRS complexes. At the same time, atrial repolarization is occurring, but it is not usually evident in an ECG because the larger QRS complex masks it. (4): Contraction of ventricular fibers begins shortly after the QRS complex appears and continues during the S-T segment (5): Repolarization of ventricular contractile fibers produces T-Wave (6): The T Wave begins, the ventricles start to relax (ventricles diastole). Then the ventricular repolarization is complete and ventricular contractile fibers relax. Both contractile fibers in the atria and ventricles are relaxed. The P wave appears again on the ECG, the atria begin to contract and the cycle starts again.

List the steps in excitation-contraction coupling in skeletal muscle, and describe the roles of the sarcolemma, transverse tubules, sarcoplasmic reticulum and the thin and thick filaments. Be certain to include the roles of modulatory proteins such as troponin and tropomyosin and of calcium ions. (Chapter 11.3, Fig. 11.10, 11.11)

(1): An nerve action potential in a somatic motor neuron is sent down the axon terminal. Voltage-gated Ca 2+ channels open in response to the nerve action potential. An increase in the Ca 2+ concentration inside the synaptic end bulb serves as a signal that triggers exocytosis (releasing Acetylcholine into the synaptic cleft). (2): ACh binds to receptors in the motor end plate. The binding of ACh opens the Na+ ligand channels triggering an end plate potential (EPP), which generates a muscle action potential. (3): The enzyme acetylcholinesterase destroys ACh so another muscle action potential does not arise unless more Ach is released from the somatic motor neuron. (4): A muscle action potential tracking down the transverse tubule triggers a change in the dihydropyridine receptors that causes the Ca 2+ release channels to open, allowing the release of Ca 2+ into the sarcoplasm. (5): Ca 2+ binds to troponin on the thin filament, exposing the myosin-binding sites on actin (6): The myosin heads bind to the actin, undergo power strokes, and release, thin filaments are pulled towards the center of the sarcomere. (7): Ca 2+ release channels close and Ca 2+-ATPase pumps use ATP to restore low levels and pump Ca 2+ back onto the sarcoplasm. (8): Tropomysoin slides back into the position where it blocks the myosin-binding sites on actin (9): Muscle relaxes

Name three (3) roles of ATP in skeletal muscle contraction and relaxation. (Chapter 11.3)

(1): Ca2+-ATPase pump uses ATP to pump Ca2+ back into the sarcoplasm and restore the low levels of Ca2+. (2): ATP hydrolysis provides energy for the myosin head to attach to actin (3): ATP binding of another ATP-binding site allows the myosin head and actin to detach.

Describe the properties of the withdrawal reflex initiated by stepping on a sharp object. (Chapter 12.3, Fig. 12.5)

(1): Stepping on a tack stimulates sensory receptors of a pain-sensitive neuron (2): This sensory neuron then generates action potentials, which propagate to the spinal cord. (3): Within the spinal cord, sensory neurons activate interneurons that extend to several spinal cord segments (4): The interneurons activate motor neurons in several spinal cord segments. As a result, the motor neurons generate action potentials, which propagate towards the axon terminals (5): Aceytholcine released by the motor neurons causes the flexor muscles in the thigh to contract, producing a withdrawal of the leg.

List the factors that can contribute to muscle fatigue and describe basis of the differences in fatigue resistance in different muscle fiber types. (Chapter 11.4)

- High extracellular concentration (impacts AP to propagate properly) -Build up of ADP - inhibition of crossbridge cycling (not stop but inhibit efficiency) -Disruption of calcium regulation, possibly by malfunctioning Ca2+ channels on the SR. Slow oxidative: slow myosin ATPase. LEAST likely to fatigue. least amount of tension. (long distance run). Fast oxidative: fast myosin ATPase. Moderate amount of tension. MODERATELY likely to fatigue. (sprint). Fast glycolytic: fast myosin ATPase. Greatest amount of tension. MOST likely to fatigue rapidly. (lift weights, single stimulation, tension drops).

Discuss the deflections (as electricity is flowing through the heart) and isoelectric events (when the heart is totally depolarized or repolarized) of the ECG. Specifically discuss what electrical event is occurring during the P wave, the QRS complex and the T wave.

- upward deflection on a ECG means the current flow vector is toward the positive electrode. - downward deflection means the current flow vector is toward the negative electrode - vector that is perpendicular to the axis of the electrode (if cell is fully depolarized or fully repolarized) causes no deflection (baseline) P Wave: atrial depolarization QRS complex: ventricular depolarization T wave: ventricular repolarization

Explain how a baroreceptor works i.e. what makes it depolarize, where it sends information to, what are the consequences of that information.

-Change in BP (increase or decrease) is sensed by the baroreceptor in the carotid arteries and aorta which leads to an increased or decreased amount of depolarization of the baroreceptor -The magnitude of depolarization is conveyed to the brain stem through the frequency of action potentials in VISCERAL AFFERENT neurons. -The control center integrates the information with a set point. If BP is too high both the parasympathetic and sympathetic motor systems are activated. -The motor pathways synapse onto effectorsEFFECTORS:Arteriolar smooth muscle Sympathetic system has less NE released. Binds to alpha receptor on smooth muscle. Less NE causes it to dilate which leads to a decrease in peripheral resistance Ventricular Myocardium Sympathetic motor system has less NE released. Binds to Beta 1 receptors. Less NE decreases the force of contraction. Leading to a decreased cardiac output SA Node Sympathetic motor system has less NE released. Binds to Beta 1 receptors, Less NE decreases the heart rate. Leading to a decreased cardiac output.Parasympathetic motor system has more ACh released onto muscarinic receptors. This leads to a decrease in heart rate. THIS SYSTEM WORKS TO EITHER INCREASE OR DECREASE BLOOD PRESSURE BASED ON THE STIMULUS. IT IS A NEGATIVE FEEDBACK LOOP

Discuss intrinsic (local tissue factors) and extrinsic (sympathetic nerves and hormones) regulators of arteriolar smooth muscle tone. Big picture idea is as follows: intrinsic, local factors regulate blood flow whereas extrinsic factors regulate blood pressure.

-Intrinsic factors or the local tissue factors they just regulate blood flow in the area. Local factors of blood flow are in response to metabolic needs of tissues. Increased CO2, H+,K+, NO leads to more blood flow. Decreased O2 leads to increased blood flow.-Extrinsic factors- are the sympathetic nerves and hormones.Sympathetic nerves- Norepinephrine on alpha receptors that constrict the vessels. Ex. GI tract. The adrenal medulla- epinephrine on Beta 2 receptors that vasodilates blood vessels to areas such has the heart, liver, and skeletal muscles.Hormones- Longer term effect. Angiotensin II is a vasoconstrictor, it INCREASES vascular resistance, Increased BP/hydrostatic pressure. Aldosterone- works through the kidneys. Increases plasma volume which increases blood pressure/hydrostatic pressure

Describe the function of higher centers in motor control. (Chapter 12.3, Fig. 12.9)

-intention to move -sensory, motor and association cortex -upper motor neuron from the cerebral cortex

Describe the series of events initiated by striking the patellar tendon with a percussion hammer that leads to extension of the lower leg (i.e. the knee jerk reflex) (Chapter 12.2, Fig. 12.3)

1. Slight stretching of the. muscle stimulates muscles sensory receptors known as muscle spindles. Muscle spindles monitor the length of the muscle. 2. Muscle spindle generates a receptor action in response to being stretched. If the receptor potential reaches threshold, it tiggers and action potential to propagate along the somatic sensory neuron through the dorsal root of the spinal cord. 3. In the integrating center in the spinal cord, the sensory neuron makes an excitatory synapse with and thereby activates a motor neuron in the ventral gray horn. 4.If the excitation is strong enough, an action potential arises in the motor neuron and propagates along its axon and extends from the spinal cord into the ventral root through the PNS to the stimulated muscle. 5. Acetylcholine is released by the action potentials at the NMJs trigger one or more action potentials in the stretched muscle, and the muscle contracts.

List the factors that determine the tension developed in a whole muscle and explain how each contributes to the amount of tension generate. (Chapter 11.6)

1. The number of active motor units. 2. The number of muscle fibers in each motor unit. 3. The fiber types of the activated motor units.

Define a motor unit and describe the order of recruitment of motor units during skeletal muscle contractions producing low, moderate and high amounts of tension. (Chapter 11.5, Fig. 11.13)

A motor neuron and the population of muscle fibers it innervates. Two motor units can generate more tension that one. Large amount of tension= more motor neurons. Motor unit 1: slow oxidative: smaller diameter muscle fibers. few fibers per motor unit. generates least tension. Motor unit 2: fast oxidative: midsized muscle fibers. moderate # of fibers per motor unit. generates moderate tension. Motor unit 3: fast glycolytic: large muscle fibers. many fibers per motor unit. generates more tension, quickly.

Compare how smooth muscle activation and relaxation differs from the activation and relaxation of skeletal muscle. (Chapter 11.8, Fig. 11.26, 11.27)

CONTRACTION STARTS MORE SLOWLY AND LASTS LONGER THAN SKELETAL MUSCLE. skeletal: calcium released from the SR as a result of an action potential can briefly saturate all of the troponin calcium binding sites= twitch smooth: (1): Calcium binds to calmodulin in the cytoplasm (2): Calcium-calmodulin complex binds to and activate myosin light chain kinase (MLCK) (3): Activated MLCK phosphorylates the myosin regulatory light chain by transferring a phosphate from ATP (4): Phosphorylated myosin head bind to actin and begin contraction by crossbridge cycling (5): Relaxation involves two main steps: (1): decreasing the Ca 2+ concentration in the sarcoplasm to resting levels (2): dephosphorylation (removing the phosphate group) of myson by myosin phosphatase - Contraction is triggered by calcium induced changed to the thick filament, whereas the contraction for skeletal muscle is due to the change in the thin filament

Compare and contrast the electrical activity of skeletal and cardiac muscle cells. Consider the duration and ionic basis of the skeletal and cardiac action potentials, and the functional consequences of their differences.

Cardiac muscle cells: contraction is slower, prevents tetanus. refractory period last almost as long as muscle contraction. Autonomic nervous system. Skeletal muscle cells: fastest to contract and relax. refractory periods are short and allow tetanus. controlled by the somatic division.

List the energy sources for muscle contraction and rank the sources with respect to their relative speed and capacity to supply ATP for contraction. (Chapter 11.4, Fig. 11.12)

Creatine kinase: one step reaction that transfers phosphate (CP) to ADP to regenerate ATP. "Storehouse" of high energy phosphate which is accumulated during rest in muscle cells. CK provides ATP during first few seconds of contraction. ATP productions is rapid, but limited by the amount of CP stored in cell. Powers very short period of muscle activity. Glycolysis: slow multistep reaction. Converts 1 Glucose to 2 ATP. Anaerobic (can produce ATP from glucose in the absence of O2). Kicks in during high intensity exercise. Large amounts of glucose can produce large quantities of ATP. Glucose can come from blood or from breakdown of muscle glycogen. Powers short periods of muscle activity. Oxidative phosphorylation: multistep slow reaction that requires O2 and mitochondria. Converts 1 glucose to 36 ATP; fatty acids to ATP; and amino acids to ATP. Phosphorylation of ADP occurs in mitochondria. Initially (first 5-10min of activity) glycogen is the major fuel. Next 30 min, blood borne glucose and fatty acids contribute fuel, eventually giving away to mostly amino acids. Powers extended periods of muscle activity. B/C muscles have sufficient amount of ATP.

Describe role of arterioles in blood distribution since we don't have enough blood to send to every body part all the time. In other words, how do the arterioles make sure that blood goes where it is needed? Be able to give examples of local factors that regulate blood flow.

Depending on the particular needs of each organ, blood flow varies from one organ to another. CO distributed to organs depends on how active they are. Blood flow remains maintained in the brain during rest and heavy exercise. However decreases in the GI tract during heavy exercise and increase in skeletal muscles.

List the factors that determine the tension developed in a whole muscle and explain how this process is controlled. (Chapter 11.5)

Frequency of stimulation: rate at which muscle fiber is stimulated by a motor neuron Muscle fiber length: develops its greatest tension when there is an optimal zone of overlap between thick and thin filaments. Sarcomere length of about 2.0-2.4 μm Shows the length-tension relationship for a skeletal muscle fiber, which indicates how the forcefulness of muscle contraction (tension) depends on the length of the sarcomeres within a muscle fiber before contraction begins. Muscle fiber diameter: a thicker diameter have more myofibrils and can generate more tension compared to muscle fibers that have a thinner diameter. (a thicker diameter have more myofibrils and can generate more tension compared to muscle fibers that have a thinner diameter). Motor unit size: size of the motor units that are activated in a muscle affects the amount of tension the muscle can generate. (The biceps muscle in the arm and the gastrocnemius muscle in the calf of the leg have as many as 2000 to 3000 muscle fibers in some motor units and muscles controlling eye movements may have 10 to 20 muscle fibers per motor unit). Motor unit recruitment: the process of increasing the number of active motor units.The smallest motor units are recruited first, with progressively larger motor units added if the task requires more force.

vasoconstriction

If radius decreases, resistance increases and blood flow decreases

vasodilation

If radius increases, resistance decreases, blood flow increases

Compare and contrast isometric and isotonic muscle contractions with respect to the duration of the latent period, the velocity of contraction and the circumstances under which each type of contraction will take place. (Chapter 11.5)

Isometric: tension generated is not enough to exceed or move the load. Muscle does not change its length while contracting. Short latent period. Occurs when you try to lift and the object is too heavy for you. Contractions occur to maintain posture and support objects in a fixed position. (Steadily holding a book in front of you). Isotonic: tension remains constant as muscle length decreases or increases. Used for moving objects contractions are used for body movements. Longer latent period. Tension that is generated during contraction is great enough to exceed the load of an object and the muscle shortens and movement is produced. (Bicep curls).

Compare and contrast laminar (smooth and quiet) and turbulent flow (disorganized flow). Discuss how these two kinds of flow are important to determining blood pressure with a blood pressure cuff. Specifically, students should discuss principles of noninvasive measurement of the BP i.e. occlusion of the vessels with the blood pressure cuff and using Korotkoff sounds to determine diastolic and systolic pressure.

Laminar: smooth, quiet flow of blood. streamlined manner that is parallel to the axis of the blood vessel. Turbulent: noisy flow of blood (Korortkoff sounds). blood moves at various angles to the vessel axis.

Explain why in lead II, the QRS and T wave are both in the upward (positive) deflection. As part of this objective, students should consider the refractory periods of the myocytes at the base and the apex of the heart.

Lead 2 is strongest and largest deflection because it is most parallel to general flow of depolarization in the heart. - QRS is ventricle depolarization - positive electrode is reading positive and the deflection is upward - T wave is still an upward deflection because even though the ventricles are depolarizing, they repolarize in reverse order from how they depolarized (dep:septum to apex to base...rep:base to apex to septum) - while base is repolarizing, the septum and apex are still depolarized and the net positive read from the electrodes causes the deflection of the T wave to be upward even though repolarization is still occurring.

Describe how changing vessel length, vessel radius and blood viscosity changes the vascular resistance (Poiseulle's Law). These formulae will be provided on the exam. Students should know how to use the formulae to solve pressure and flow problems.

Length and viscosity are proportional to resistance. If length or viscosity increase then resistance increases. Radius is inversely proportional to the resistance. If radius increases the resistance decreases. RADIUS HAS THE BIGGEST INFLUENCE ON RESISTANCE.

Calculate mean arterial pressure (diastolic + 1/3 (systolic-diastolic)) & describe BP measurement using a blood pressure cuff. Students should know this formula.

Mean Arterial Pressure = diastolic + 1/3 (systolic-diastolic)

List the regions of the brain involved in middle level of motor control and describe the main function that these structures serve. (Chapter 12.4, Fig. 12.10, 12. 11, Chapter 12.5, Fig. 12.12, 12.13, Chapter 12.6, Fig. 12.14)

Middle level of control: motor programs to coordinate movements based on intention, sensory feedback, etc. Basal nuclei: controls initiation of movement, suppression of unwanted movement, regulation of muscle tone, regulation of non-motor processes Cerebellum: monitor intention for movement and actual movement, compares command signals with sensory information, send out corrective feedback. Thalamus: motor center in brain stem

Explain the scientific basis for ECG measurement. In your answer, address the ability of the body to conduct electricity and the placement of the recording electrodes. Students are not held responsible for knowing the lead configurations of all 12 leads but rather understanding how any given lead (two recording electrodes and a ground electrode) is used to detect the ECG.

Surface electrodes are used to record internal electrical activity - salt solutions, such as NaCl based ECF (saline), are good conductors of electricity. - ECGs (or EKGs) show the summed electrical activity generated by all cells of the heart. Using leads to detect ECG: - one electrode acts as the positive electrode of a lead, and a second electrode acts as the negative electrode of the lead. - the third electrode is inactive- when an electrical wave moving through the heart is directed toward the positive electrode, the ECG wave goes up from the baseline. If net charge movement is toward the negative electrode, the wave points down

Define preload making sure to include sarcomere length in your answer. Discuss how venous return regulates cardiac output (Frank-Starling law of the heart).

The degree of stretch on the heart before it contracts. Proportional to End Diastolic Volume. The greater the EDV, the more forceful the next contraction. Frank-Starling law of the heart: the more the heart fills with blood during diastole, the greater the force of contraction during systole.

Contrast the duration of a muscle action potential with the duration of a muscle contraction, and explain the significance of this difference. (Chapter 11.3, 11.5 Fig. 11.9)

The duration of the skeletal muscle action potential is very brief, lasting only about 1-2 msec. Once an action potential is generated in a skeletal muscle fiber, it propagates along the sarcolemma and T tubules via continuous conduction, the same mechanism used for propagation of nerve action potentials along unmyelinated axons. Consists of two main phases: depolarizing phase and repolarizing phase Twitches of skeletal muscle fibers last anywhere from 20 to 200 msec. This is very long compared to the brief 1-2 msec that a muscle action potential lasts. It is longer because muscle twitches consist of the latent period, contraction period, and relaxation period. Latent period (brief delay that occurs between application of the stimulus and beginning of contraction) which lasts 2 msec. Excitation-contraction coupling occur. The muscle action potential sweeps along the sarcolemma and into the T tubules, causing the release of calcium ions from the sarcoplasmic reticulum. Contraction period which lasts 10-100 msec. Ca2+ binds to troponin, myosin-binding sites on actin are exposed, and myosin cross bridges form. As a result, peak tension develops in the muscle fiber. Relaxation period lasts 10-100 msec. Ca2+ is actively transported back into the sarcoplasmic reticulum, myosin-binding sites are covered by tropomyosin, myosin heads detach from actin, and tension in the muscle fiber decreases.

Compare and contrast the organization of the somatic nervous system versus the autonomic nervous system. (Table 10.5)

autonomic nervous system: -smooth muscle, cardiac muscle, and glands. -Usually a two-neuron pathway: (1) a preganglionic neuron that extends from CNS to an autonomic ganglion and (2) a postganglionic neuron that extends from the autonomic ganglion to the effector. Alternatively, a preganglionic neuron may extend from CNS to synapse with chromaffin cells of the adrenal medulla. -release either acetylcholine (ACh) or norepinephrine (NE). Chromaffin of the adrenal medulla releases epinephrine and NE into bloodstream as hormones. -Usually cholinergic or adrenergic. -may be excitatory or inhibitory -Involuntary control from hypothalamus, brain stem, and spinal cord. somatic nervous system: -skeletal muscle -one neuron pathway: a single somatic motor neuron extends from the CNS to synapse directly with the effector. -releases ACh -Cholinergic -always excitatory -voluntary control from cerebral cortex, with contributions from the basal nuclei, cerebellum, brain stem, and spinal cord.