backup2

Question 2

Carbon double bonds

1. A C=C bond is a ..?…?…?.. in a molecule.

It should be the site of a lot of .?…?..

Answer 2

1. A C=C bond is a reaction hot spot in a molecule.

It should be the site of a lot of chemical action

Question 3

nucleophilic substitution

A nucleophile is an ..?.. rich species that will react with an electron ..?.. species
A substitution implies that one group ..?.. another.

Answer 3

What does the term “nucleophilic substitution” imply ?

A nucleophile is an electron rich species that will react with an electron poor species
A substitution implies that one group replaces another.

Nucleophilic substitution reactions occur when an electron rich species, the nucleophile, reacts at an electrophilic saturated C atom attached to an electronegative group (important), the leaving group

The electrophilic C can be recognised by looking for the polar σ bond due to the presence of an electronegative substituent (esp. C-Cl, C-Br, C-I and C-O)

Nucleophilic substitution reactions are an important class of reactions that allow the interconversion of functional groups.

Of particular importance are the reactions of alkyl halides (R-X) and alcohols (R-OH)

For alcohols, the range of substitution reactions possible can be increased by utilising the tosylates (R-OTs), an alternative method of converting the -OH to a better leaving group.

Question 4

nucleophilic substitution

1. What are the three conditions for Nucleophilic substitution reactions to occur?

Answer 4

_{What does the term “nucleophilic substitution” imply ?}

_{A nucleophile is an electron rich species that will react with an electron poor species<br></br>A substitution implies that one group replaces another.}

Nucleophilic substitution reactions occur when an

electron rich species, the nucleophile,

reacts at an electrophilic saturated C atom attached to

an electronegative group (important), the leaving group

_{The electrophilic C can be recognised by looking for the polar σ bond due to the presence of an electronegative substituent (esp. C-Cl, C-Br, C-I and C-O)}

_{Nucleophilic substitution reactions are an important class of reactions that allow the interconversion of functional groups.}

_{Of particular importance are the reactions of alkyl halides (R-X) and alcohols (R-OH)}

_{For alcohols, the range of substitution reactions possible can be increased by utilising the tosylates (R-OTs), an alternative method of converting the -OH to a better leaving group.}

Question 5

nucleophilic substitution

1. How can an electrophilic saturated C atom can be recognised?

Answer 5

_{What does the term “nucleophilic substitution” imply ?}

_{A nucleophile is an electron rich species that will react with an electron poor species<br></br>A substitution implies that one group replaces another.}

_{Nucleophilic substitution reactions occur when an electron rich species, the nucleophile, reacts at an electrophilic saturated C atom attached to an electronegative group (important), the leaving group}

The electrophilic C can be recognised by looking for the polar σ bond due to the presence of an electronegative substituent (esp. C-Cl, C-Br, C-I and C-O)

_{Nucleophilic substitution reactions are an important class of reactions that allow the interconversion of functional groups.}

_{Of particular importance are the reactions of alkyl halides (R-X) and alcohols (R-OH)}

_{For alcohols, the range of substitution reactions possible can be increased by utilising the tosylates (R-OTs), an alternative method of converting the -OH to a better leaving group.}

Question 6

nucleophilic substitution

1. Nucleophilic substitution reactions are an important class of reactions that allow the ..?.. of functional groups

Answer 6

What does the term “nucleophilic substitution” imply ?

Nucleophilic substitution reactions are an important class of reactions that allow the interconversion of functional groups.

_{Of particular importance are the reactions of alkyl halides (R-X) and alcohols (R-OH)}

_{For alcohols, the range of substitution reactions possible can be increased by utilising the tosylates (R-OTs), an alternative method of converting the -OH to a better leaving group.}

Question 7

nucleophilic substitution

_{Nucleophilic substitution reactions are an important class of reactions that allow the interconversion of functional groups.}

1. Of particular importance are the reactions of ..?….?.. and ..?..

Answer 7

What does the term “nucleophilic substitution” imply ?

Of particular importance are the reactions of alkyl halides (R-X) and alcohols (R-OH)

_{For alcohols, the range of substitution reactions possible can be increased by utilising the tosylates (R-OTs), an alternative method of converting the -OH to a better leaving group.}

Question 8

Some smooth muscle exhibits spontaneous contractile activity in the absence of either nerve or hormonal stimuli.

1. Where in the body for example?

Answer 8

Some smooth muscle exhibits spontaneous contractile activityin the absence of either nerve or hormonal stimuli. The plasma membranes of these fibers do not maintain a stable resting membrane potential. Instead the resting membrane potential gradually drifts towards threshold where it triggers an action potential (Figure 49). Following repolarization the membrane again begins to depolarize. This is property is called pacemaker activity.

Pacemakers are found within the GI tract.

Question 9

What are the differences between

MULTI-UNIT smooth muscle fibers

and

SINGLE UNIT smooth muscle fibers

Answer 9

SINGLE VERSUS MULTI-UNIT FIBERS

Smooth muscle fibers do not have a specific neuro-muscular junction. Instead as the autonomic nerve nears a bundle of smooth muscle, it divides into many branches each containing a series of swellings (called varicosities) filled with vesicles of neurotransmitters.

MULTI-UNIT smooth muscle fibers are innervated independently. The fibers are not connected by gap junctions. Depolarization of one fiber is followed by contraction of that fiber only. These fibers are richly innervated by the autonomic nervous system. Nervous stimuli and hormones cause contraction (or relaxation) of these fibers, not stretch. The smooth muscle of the lung airways, in the walls of large arteries, and attached to the hair of the skin are multi-unit fibers.

SINGLE UNIT smooth muscle fibers are connected by gap junctions. Depolarization of one fiber triggers synchronous depolarization throughout the bundle followed by contraction of the fiber bundle. That is, many fibers act as one sheet. Single unit fibers are found in the walls of small blood vessels, the GI tract, and uterus where stretching of one fiber creates a coordinated contraction

Question 10

In smooth muscle does Ca++ regulate the thick filament or the thin filament?

Answer 10

In smooth muscle, coupling between the membrane action potentials and contraction is mediated by calcium ions (Ca++).

Calcium regulates the thick filament (myosin) to enable cross bridge formation and contraction.

Question 11

Draw cardiac muscle cell(s )

Answer 11

cardiac muscle cell

Question 12

How many of the cardiac muscle cells are conducting (the intrinsic pacemakers)?

Answer 12

CONDUCTING cardiac muscle cells are ~ 1% of the cardiac muscle cells.

These are large diameter cells that do not produce tension, instead they are specialized for excitation.

They constitute a network in the heart known as a conduction system.

They are connected to the contractile cells by gap junctions.

The conducting fibers are filled mostly with glycogen and have few myofilaments. These cells are the intrinsic pacemakers. We will deal with their action potentials in the next lecture.

Question 13

What sort of muscle fibres are the contractile cardiac muscle cells?

Answer 13

CONTRACTILE cardiac muscle cells are slow oxidative muscle fibers.

These fibers form the walls of the heart, shorten and produce tension. They use glucose and fatty acids as substrates.

Question 14

Acid-base

1. Derive the Henderson-Hasselbalch approximation

starting with a buffer solution

HA H⁺ + A¯

pH = pKa + log ([A−] / [HA])

Answer 14

The Henderson-Hasselbalch approximation allows us one method to approximate the pH of a buffer solution

pH = pKa + log ([A−] / [HA])

HA is the acid, A- is the conjugate base

padlet

derivation

Question 15

Acid-base

1. What is the Henderson-Hasselbalch approximation used for?
2. Write the equation

Answer 15

The Henderson-Hasselbalch approximation allows us one method to approximate the pH of a buffer solution

pH = pKa + log ([A−] / [HA])

HA is the acid, A- is the conjugate base

padlet

derivation

Question 16

Cardiac muscle

1. In cardiac muscle the action potential activates the C++ gates in the ???

Answer 16

ELECTRICAL – CONTRACTION (E-C) COUPLING

As in skeletal muscle, contraction in cardiac muscle is dependent on the entry of Ca++ from the T tubule (Figure 51).

Depolarization of the T tubule membrane opens the voltage gated Ca++ channels (dihydropyridine receptor), permitting the entry of a small amount of Ca++.

This Ca++ opens the Ca++ gated Ca++ channel (ryanodine receptor) on the sarcoplasmic reticulum (SR) thereby releasing a lot of Ca++ into the cytoplasm.

In turn, Ca++ binds to troponin which unmasks the actin (thin filament), cross bridges form, and shortening occurs.

With repolarization of the T tubule membrane, no further Ca++ enters the cells and the SR CaATPase removes Ca++ from the cytoplasm. This removal of Ca++ ends the contractile cycle and the muscle relaxes

Question 17

Cardiac muscle

1. Describe the three steps in the ELECTRICAL – CONTRACTION (E-C) COUPLING in cardiac muscle

Answer 17

ELECTRICAL – CONTRACTION (E-C) COUPLING

As in skeletal muscle, contraction in cardiac muscle is dependent on the entry of Ca++ from the T tubule (Figure 51).

1. Depolarization of the T tubule membrane opens the voltage gated Ca++ channels (dihydropyridine receptor), permitting the entry of a small amount of Ca++.
2. This Ca++ opens the Ca++ gated Ca++ channel (ryanodine receptor) on the sarcoplasmic reticulum (SR) thereby releasing a lot of Ca++ into the cytoplasm.
3. In turn, Ca++ binds to troponin which unmasks the actin (thin filament), cross bridges form, and shortening occurs.

With repolarization of the T tubule membrane, no further Ca++ enters the cells and the SR CaATPase removes Ca++ from the cytoplasm. This removal of Ca++ ends the contractile cycle and the muscle relaxes

Question 18

Describe the phases of ACTION POTENTIAL OF CONTRACTILE CARDIAC CELLS

(0-4)

Answer 18

ACTION POTENTIAL OF CONTRACTILE CARDIAC CELLS

The action potential of the contractile cardiac muscle fiber (Figure 52) is longer in duration (200-220 msec) than that seen in skeletal muscle (2 msec). In cardiac cells there are four phases to the action potential.

Phase 0, voltage gated Na+ channels open.

Phase 1, voltage gated Na+ channels inactivate and voltage gated K+ channels open.

Phase 2 (plateau), voltage gated Ca++ channels open and voltage gated K+ channels remain open.

Phase 3, only voltage gated K+ channels are open and cells repolarize.

Phase 4, all of the voltage gated channels are closed and the resting membrane potential is restored by the Na/K ATPase.

Note that the entry of Ca++ in phase 2 is essential for initiating contraction and triggering the opening of the Ca++ gated Ca++ release channel (ryanodine receptor).

One other point, each action potential results in one contraction. One contraction (twitch) is ~250 msec, almost the same duration as the action potential (200 msec). This is due to the prolonged plateau phase 2.

Question 19

Cardiac muscle

1. What is the absolute refractory period of cardiac muscle?
2. How long does the action potential last?
3. How long is a single contraction?
4. What are the implications for tetanus of the heart muscle?

Answer 19

REFRACTORY PERIOD AND ABSENCE OF TETANUS

Absolute refractory period of the cardiac muscle action potential refers to the time interval when the voltage gated sodium channels are inactivated.

The absolute refractory period lasts ~180 msec.

The action potential lasts 200-220 msec.

A single contraction is 250 msec.

_{Recall that these voltage gated Na+ channels must undergo a conformational change from an “inactivated” state to a “closed” state before they can reopen and initiate another action potential. As a consequence of phase 2, the voltage gated Na+ channels remain “inactivated” for an extended period of time and do not “close” until repolarization in phase 3 (~180 msec). No amount of stimulus can cause an action potential during the absolute refractory period.}

An important point regarding the refractory period is that contractions cannot sum and therefore there is no fused tetanus (summed contractions). Fused tetanus in the heart would lead to death as it would prevent the rhythmic pumping of blood.

Question 20

After a skeletal muscle fiber is treated with a membrane permeable drug that speeds up the action of the SR Ca+2-ATPase, how would the first twitch differ?

the twitch would last longer

the twitch would be shorter

the twitch would last the same amount of time

the twitch would produce more tension

Answer 20

the twitch would be shorter

the SR Ca+2-ATPase pumps Ca++ back into the Sarcoplasmic Reticulum

Question 21

After a skeletal muscle fiber is treated with a membrane permeable drug that speeds up the action of the SR Ca+2-ATPase, how would contraction differ after multiple and frequent action potentials?

A the maximal tension would be increased compared to an untreated fiber

B fused tetanus would be reached in the same amount of time as an untreated

fiber

C fused tetanus would be reached later than an untreated fiber

D fused tetanus would be reached sooner than an untreated fiber

Answer 21

C fused tetanus would be reached later than an untreated fiber

the SR Ca+2-ATPase pumps Ca++ back into the Sarcoplasmic Reticulum

Question 22

Which of the following is the typical order of motor unit recruitment?

A slow-oxidative, fast-glycolytic, fast-oxidative

B slow-oxidative, fast-oxidative, fast-glycolytic

C fast-oxidative, slow-oxidative, fast-glycolytic

D fast-glycolytic, fast-oxidative, slow-oxidative

Answer 22

B slow-oxidative, fast-oxidative, fast-glycolytic

Skeletal muscle fibers are classified into one of three types distinguished by the speed of their myosin ATPase and preferred metabolism:

fast, glycolytic fibers fatigue quickly
fast, oxidative, glycolytic fibers resist fatigue
slow, oxidative fibers resist fatigue

Recruitment is the process of activating different types of muscle fibers within a fascicle in response to need. Recruitment starts with slow, oxidative fibers that do not provide a lot of force but can provide fine muscle control. If more tension is needed, fast-oxidative-glycolytic fibers can be recruited. Finally, fast, glycolytic fibers that fatigue rapidly increase tension the most dramatically are recruited.

Question 23

Which of the following types of muscles have sufficient numbers of gap junctions between fibers to propagate action potentials between cells?

A both cardiac muscle and single-unit smooth muscle

B cardiac muscle only

C multi-unit smooth muscle only

D both cardiac muscle and multi-unit smooth muscle

E single-unit smooth muscle only

Answer 23

A both cardiac muscle and single-unit smooth muscle

Question 24

Smooth muscle cells differ from skeletal muscle cells in that smooth muscle does NOT contain:

troponin–tropomyosin complexes

myosin ATPase activity

dense bodies

thin filaments

Answer 24

troponin–tropomyosin complexes

Question 25

In smooth muscle cells, a pacemaker potential differs from a graded potential because pacemaker potentials: activate with the efflux of Na+ vary in size always reach threshold activate with the influx (entry) of Cl-

Answer 25

[always reach threshold](http://padlet.com/davidofbuderim/4ova3k99hh1l)

Question 26

Angular momentum 1. in terms of mass and velocity L = 2. In terms of linear momentum L = 3. In terms of angular velocity L =

Answer 26

L = m v r (v is tangential to r) L = ρ r (ρ is tangential to r) L = m ω r²

Question 27

Draw the four graphs showing results of the photoelectric effect

Answer 27

[four graphs showing results of the photoelectric effect](http://padlet.com/davidofbuderim/oqqr8a6oa1vs)

Question 28

1. What is the Rydberg equation 1/λ = 2. What is it used for?

Answer 28

[Rydberg equation](http://padlet.com/davidofbuderim/oqqr8a6oa1vs) 2. Photoelectric effect / emission spectra

Question 29

Heart Electrical Activity Tom, an 80 yr old male, presents to his physician with a resting heart rate of 35 bpm. 1. You classify his heart rate as: A. Normal B. Bradycardia C. Tachycardia 2. His pacemaker is most likely located at the: A. Sinoatrial node B. Atrial-ventricular node C. His Bundle-Purkinje

Answer 29

Answer 1: B. Bradycardia Answer 2: C. His Bundle-Purkinje

Question 30

1. The valves of the heart open and close in response to: A. active contraction of the papillary muscles B. pressure differences between the heart chambers C. shortening of the tendons within the ventricle D. autonomic nervous stimulation

Answer 30

1. B pressure differences between the heart chambers

Question 31

If Jim has a cardiac output of 3 L per min at a resting heart rate of 30 bpm. If his heart rate increases to 90 bpm but his cardiac output remains the same what happens to his stroke volume? A. His stroke volume increases by a factor of 3 B. His stroke volume decreases to 33 ml C. His stroke volume remains unchanged

Answer 31

B. His stroke volume decreases to 33 ml

Question 32

Cardiac Performance Consider the Pressure-Volume (PV) Loop below. The black PV loop (designated by ABCD) depicts the Left Ventricle of a normal heart. 1. The red PV loop depicts the LV of a heart with: A. decreased systemic pressure (after load) B. increased systemic pressure (after load)

Answer 32

Answer 1: B. increased systemic pressure (after load)

Question 33

Cardiac Performance Consider the Pressure-Volume (PV) Loop below. The black PV loop (designated by ABCD) depicts the Left Ventricle of a normal heart. 2. What occurs at C and G? A. AV valve closes B. aortic valve opens C. AV valve opens D. aortic valve closes

Answer 33

Answer 2: B. aortic valve opens

Question 34

Cardiac Performance Consider the Pressure-Volume (PV) Loop below. The black PV loop (designated by ABCD) depicts the Left Ventricle of a normal heart. 3. What occurs at D and H? A. AV valve closes B. aortic valve opens C. AV valve opens D. aortic valve closes

Answer 34

Answer 3: D. aortic valve closes

Question 35

Cardiac Performance Consider the Pressure-Volume (PV) Loop below. The black PV loop (designated by ABCD) depicts the Left Ventricle of a normal heart. 4. Are the stroke volumes (SV) for these two hearts equal? A. Yes, each is 60 mls B. No, red loop SV is 150 ml; black loop SV is 120 mls. C. No, red loop SV is 90 mls; black loop SV is 60 mls

Answer 35

Answer 4: A. Yes, each is 60 mls

Question 36

Cardiac Performance Consider the Pressure-Volume (PV) Loop below. The black PV loop (designated by ABCD) depicts the Left Ventricle of a normal heart. 5. Are the ejection fractions of these two hearts equal? A. Yes, each is 50% B. No. Black loop EJ = 60/120 x 100 = 50%; Red loop EJ = 60/150 x 100 = 40%

Answer 36

Answer 5: B. No. Black loop EJ = 60/120 x 100 = 50%; Red loop EJ = 60/150 x 100 = 40%

Question 37

The Circulatory System 1. If blood flow to an arm is obstructed for more than 30 seconds while taking a blood pressure, then release of the cuf will be followed by a temporary rise in blood flow and a return to resting levels. The higher blood flow is caused by \_\_\_. A. an increase in total peripheral resistance (TPR). B. a temporary increase in mean arterial pressure. C. local vasodilation due to the build up of metabolites. D. shifting blood flow from other organs.

Answer 37

Answer 1: C. local vasodilation due to the build up of metabolites.

Question 38

The Circulatory System 2. In advanced atherosclerosis, calcified plaques cause the normally muscular arteries to become narrow. What happens to resistance in these vessels? A. Resistance increases B. Resistance decreases C. Resistance remains unchanged

Answer 38

Answer 2: A. Resistance increases

Question 39

The Circulatory System 3. If advanced atherosclerosis, calcified plaques cause the normally muscular arteries to become narrow. If cardiac output remains unchanged, what happens to MAP? A. MAP increases B. MAP decreases C. MAP remains unchanged

Answer 39

Answer 3: A. MAP increases

Question 40

The Circulatory System 4. If MAP increases in an eighty year old male, what happens to afterload? A. Afterload is increased B. After load is decreased C. After load is unchanged?

Answer 40

Answer 4: A. Afterload is increased Afterload is the pressure against which the heart must work to eject blood during systole (systolic pressure). The lower the afterload, the more blood the heart will eject with each contraction. Like contractility, changes in afterload will raise or lower the Starling curve relating stroke volume index to LAP. The effect of afterload on stroke colume is due to the fact that the maximum pressure that the heart can develop is smaller at lower ventricular volumes. Therefore, if the systolic pressure is lower, the heart will be able to contract to a smaller volume at the end of systole. This will result in an improved stroke volume. Conversely, if the systolic pressure is higher, the heart will be unable to contract to as small a vollume at the end of systole and the stroke volume index will be decreased.

Question 41

1. Mary rose quickly from her bed to answer the door. This change in body position resulted in: A. Increased dilation of peripheral blood vessels B. Decreased firing of the carotid baroreceptors C. Increased parasympathetic stimulation of the SA node D. Unchanged venous return

Answer 41

Answer 1: B. Decreased firing of the carotid baroreceptors

Question 42

2. Total peripheral resistance decreases in a runner during strenuous exercise due to: A. increased parasympathetic nervous stimulation of the working skeletal muscle B. increased vasoconstriction of the large veins of the body C. increased metabolites in the IS surrounding the muscle

Answer 42

Answer 2: C. increased metabolites in the IS surrounding the muscle

Question 43

3. If two liters of blood are lost from the body, arterial hypotension occurs. This can lead to the movement of fluid from the tissues into the capillaries in response to: A. Higher capillary hydrostatic pressure B. Lower capillary hydrostatic pressure C. Higher capillary oncotic pressure D. Lower capillary oncotic pressure

Answer 43

Answer 3: B. Lower capillary hydrostatic pressure

Question 44

4. Does MAP (increase, decrease or remain unchanged) during anaerobic exercise such as weight lifting? A. Increases B. Decreases C. Remains unchanged

Answer 44

Answer 4: A. Increases

Question 45

Capillaries are best described as: E. thin walled vessels which carry blood deficient in oxygen. C. thin walled vessels which convey blood toward the heart. A. thin walled vessels which permit exchange of materials between blood and interstitial fluid. B. thick walled vessels which convey blood away from the heart. D. thick walled vessels which carry blood rich in oxygen.

Answer 45

A. thin walled vessels which permit exchange of materials between blood and interstitial fluid. Well done!

Question 46

2. Valves are found: A. in the heart B. in the veins C. in the arteries D. A and B E. A, B and C

Answer 46

D. A and B Well done!

Question 47

3. The driving force of blood flow is a(n) __________ gradient. B. volume A. osmotic D. gravity C. pressure

Answer 47

C. pressure Well done!

Question 48

4. Vascular resistance is related to the: B. diameter of a blood vessel D. viscosity of the blood A. length of a blood vessel C. nature of the blood flow (turbulent vs lamellar) E. A, B, C, and D

Answer 48

E. A, B, C, and D Well done!

Question 49

5. Each of the following changes will result in increased blood flow to a tissue EXCEPT: B. decreased vessel diameter A. increased blood volume D. decreased peripheral resistance C. increased blood pressure

Answer 49

B. decreased vessel diameter Well done!

Question 50

6. As blood vessel length increases: A. resistance increases B. flow decreases C. friction decreases D. A and B E. A, B and C

Answer 50

D. A and B Well done!

Question 51

7. The steep repolarization of phase 3 of the cardiac contractile cell’s action potential is due to which ion(s)? A. Ca2+ B. K+ C. Na+ E. A and C D. A and B

Answer 51

B. K+ Well done!

Question 52

8. Phase 2 (plateau) of the cardiac contractile cell action potential is due to a combination of: D. Ca++ influx and K+ efflux A. Na+ efflux and K+ influx B. Na+ influx and Ca++ influx C. Ca++ efflux and K+ influx

Answer 52

D. Ca++ influx and K+ efflux Well done!

Question 53

9. The volume of blood ejected from each ventricle during a contraction is called the: A. end-diastolic volume E. cardiac reserve C. stroke volume B. end-systolic volume D. cardiac output

Answer 53

C. stroke volume Well done!

Question 54

10. Each of the following factors will increase cardiac output EXCEPT: B. Increased parasympathetic stimulation D. Increased heart rate C. Increased sympathetic stimulation A. Increased venous return

Answer 54

B. Increased parasympathetic stimulation Well done!

Question 55

11. Each of the following conditions would increase the heart rate EXCEPT: D. increased permeability of the myocardial membrane to sodium ion B. increased parasympathetic stimulation of nodal fibers C. increased levels of epinephrine in the interstitial fluid surrounding the myocardium A. increased sympathetic stimulation of nodal fibers

Answer 55

B. increased parasympathetic stimulation of nodal fibers Well done!

Question 56

12. Ventricular contraction begins just after ___ begins. B. QRS complex A. P wave E. ST segment C. T Wave D. PR segment

Answer 56

B. QRS complex Well done!

Question 57

13. Ventricular repolarization occurs during: D. PR segment A. P wave B. QRS complex C. T Wave E. ST segment

Answer 57

C. T Wave Well done!

Question 58

14. Atrial depolarization occurs during: A. P wave D. PR segment B. QRS complex E. ST segment C. T Wave

Answer 58

A. P wave Well done!

Question 59

15. If the blood pressure doubled at the same time that the peripheral resistance were doubled, the blood flow through a vessel would be: C. 16 times greater D. 1/16 as much B. halved A. doubled E. unchanged

Answer 59

E. unchanged Well done!

Question 60

16. Abnormally slow conduction through the ventricles would change the \_\_\_\_\_\_\_\_in an EKG. B. T wave A. P wave C. QRS complex D. B and C

Answer 60

D. B and C Well done!

Question 61

17. The main site of variable resistance in the systemic circulation, contributing more than 60% of the total resistance are: E. veins A. muscular arteries B. elastic arteries D. venules C. arterioles

Answer 61

C. arterioles Well done!

Question 62

18. When a person rises quickly from a prone position: D. heart rate decreases A. the carotid baroreceptors become more active B. venous return is unchanged C. reflex vasoconstriction of the peripheral blood vessels occurs

Answer 62

C. reflex vasoconstriction of the peripheral blood vessels occurs Well done!

Question 63

19. Parasympathetic stimulation of the sinoatrial (SA) node will: A. hyperpolarize the pacemaker cells B. decrease the heart rate C. increase the rate of depolarization E. A and C D. A and B

Answer 63

D. A and B Well done!

Question 64

20. Stretching a myocardial cell: A. decreases the force of a contraction B. allows more K+ to enter C. increases the force of contraction D. A and B E. B and C

Answer 64

C. increases the force of contraction Well done!

Question 65

The impulse from the pacemaker cells flows in a unidirectional manner throughout the heart via specialized conducting tissue (Figure 55) and into the heart muscle. 1. Draw and identify the tissues and the order

Answer 65

[padlet-electrical conduction in the heart](http://padlet.com/davidofbuderim/gpf807lxm9f9)

Question 66

1. Draw membrane potential vs time for pacemaker cells 2. Describe the flow of ions at each stage

Answer 66

[Pacemaker cells](http://padlet.com/davidofbuderim/gpf807lxm9f9) have the unique property of being able to generate action potentials spontaneously (i.e. without input from the nervous system). They can generate an action potential because their resting membrane potential (- 60mV) is unstable. This potential exists because the pacemaker cells have unusual channels that are permeable to both Na + and K+. These channels are called If channels. _{The "f" is derived from the fact that they were originally called "funny" channels because the If channels are Na+ channels with unusual properties}. When the If channels opens, the influx of Na+ exceeds the efflux of K + and the net influx of positive charges slowly depolarizes the cell. As the membrane potential becomes more positive, the If channels close and the Ca++ channels open transiently, which further depolarize the cell. When the threshold potential is reached, a burst of Ca++ channels open, more Ca++ rushes in, and a steep phase of depolarization (Phase2) occurs (Figure 56). At the peak of the action potential, K+ channels open, K+ rushes out of the cell and the cell repolarizes

Question 67

1. What unusual ion channels do pacemaker cells in the heart have? 2. What are they called?

Answer 67

[Pacemaker cells](http://padlet.com/davidofbuderim/gpf807lxm9f9) have the unique property of being able to generate action potentials spontaneously (i.e. without input from the nervous system). They can generate an action potential because their resting membrane potential (- 60mV) is unstable. This potential exists because the pacemaker cells have **unusual channels that are permeable to both Na + and K+**. These channels are **called If channels**. _{The "f" is derived from the fact that they were originally called "funny" channels because the If channels are Na+ channels with unusual properties}. When the If channels opens, the influx of Na+ exceeds the efflux of K + and the net influx of positive charges slowly depolarizes the cell. As the membrane potential becomes more positive, the If channels close and the Ca++ channels open transiently, which further depolarize the cell. When the threshold potential is reached, a burst of Ca++ channels open, more Ca++ rushes in, and a steep phase of depolarization (Phase2) occurs (Figure 56). At the peak of the action potential, K+ channels open, K+ rushes out of the cell and the cell repolarizes

Question 68

In normal hearts which of the several pacemakers available sets the pace?

Answer 68

The pacemaker cells set the rate of the heartbeat. They are anatomically distinct from the contractile cells because they have no organized sarcomeres and therefore do not contribute to the contractile force of the heart. There are several different pacemakers in the heart but the **sinoatrial node (SA)** is the fastest. **In normal hearts, the SA node is the pacemaker**. The other conduction tissue (AV), Bundle of His and Purkinje Fibers will take over in disease states according to their speed of depolarization (AV \> bundle of His \>Purkinje).

Question 69

1. Which parts of the nervous system modulate heart rate? 2. How is heart rate slowed? 3. How is heart rate sped up?

Answer 69

HEART RATE (HR) can be modulated by **autonomic nervous stimulation**. Increased **parasympathetic** stimulation of muscarinic receptors on the heart **slows the firing of the SA node**. Parasympathetic stimulation does so by delaying the closing of K+ channels (efflux). The increased K+ efflux further hyperpolarizes the cells and slows the opening of the If channels. In contrast, **sympathetic stimulation speeds heart rate by shortening the time to threshold.** Sympathetic stimulation increases Na influx via the If channels and closes the K channels

Question 70

How are myocardial contractile cells linked mechanically? and electrically?

Answer 70

MYOCARDIAL CONTRACTILE CELLS are tightly linked to one another by **intercalated discs, specialized adhesive junctions, which ensure transmission of force** from one myocardial cell to an adjacent cell. The cells also contain **gap junctions that facilitate transmission of electrical impulses** from cell to cell. Myocardial contractile cells have a resting membrane potential of approximately -85 millivolts (mV). Depolarization occurs when the permeability to sodium increases, and sodium flows into the cell (Phase 0, Figure 57). As the membrane potential reaches about +20 mV, the voltage gated sodium channels inactivate. The muscle cell begins to repolarize as K+ leaves the cell through open voltage gated K+ channels (Phase 1). At this membrane potential, voltage gated Ca++ channels open causing the action potential to flatten as the K+ efflux balances the Ca++ influx. The plateau (Phase 2) ends when Ca ++ channels close and K+ efflux exceeds Ca++ influx. In Phase 3, K+ efflux repolarizes the muscle cell. The resting membrane potential is maintained by the activity of the Na-K ATPase (Phase 4)

Question 71

Fast action potential of cardiac contractile cell has four phases (0-4) 1. Describe each phase in terms of gates and ions

Answer 71

Myocardial contractile cells have a resting membrane potential of approximately -85 millivolts (mV). Depolarization occurs when the permeability to sodium increases, and sodium flows into the cell (Phase 0, Figure 57). As the membrane potential reaches about +20 mV, the voltage gated sodium channels inactivate. The muscle cell begins to repolarize as K+ leaves the cell through open voltage gated K+ channels (Phase 1). At this membrane potential, voltage gated Ca++ channels open causing the action potential to flatten as the K+ efflux balances the Ca++ influx. The plateau (Phase 2) ends when Ca ++ channels close and K+ efflux exceeds Ca++ influx. In Phase 3, K+ efflux repolarizes the muscle cell. The resting membrane potential is maintained by the activity of the Na-K ATPase (Phase 4)

Question 72

1. What does an ECG represent in general? 2. What does each deflection represent?

Answer 72

An ECG recording is the **sum of all of the electrical potentials** generated by all the cells of the heart at any instance in time. Each deflection (wave) of the ECG **represents either depolarization or repolarization** of the specific parts of the heart. Because depolarization occurs before mechanical contraction, the waves of depolarization can be associated with contraction and relaxation of the atria and the ventricles. A typical ECG recording and the waves are shown below (Figure 58). The P wave corresponds to depolarization of the atria. The QRS complex corresponds to depolarization of the ventricles. The T wave corresponds to repolarization of the ventricle.

Question 73

Draw a typical ECG, name the parts, and what they represent

Answer 73

_{An ECG recording is the sum of all of the electrical potentials generated by all the cells of the heart at any instance in time. Each deflection (wave) of the ECG represents either depolarization or repolarization of the specific parts of the heart. Because depolarization occurs before mechanical contraction, the waves of depolarization can be associated with contraction and relaxation of the atria and the ventricles.} [A typical ECG recording](http://padlet.com/davidofbuderim/gpf807lxm9f9) and the waves are shown below (Figure 58). The P wave corresponds to depolarization of the atria. The QRS complex corresponds to depolarization of the ventricles. The T wave corresponds to repolarization of the ventricle.

Question 74

In the heart, electrical activity (depolarization and repolarization) proceeds in a sequential manner. 1. Starts in ? 2. Moves through? Name of wave? Physical result? 3. Where next? Something happens to it? Physical result? 4. Where next?

Answer 74

1. Normally each heart beat starts in the pacemaker cells of the **sinoatrial (SA) node** located **in the right atria**. 2. From the SA node, the wave of depolarization moves through **both atria (P wave), resulting in atrial contraction.** 3. The impulse then passes **through the intranodal pathways** connecting the SA node with the **atrioventricular node (AV node)**. At the AV node the **impulse slows** allowing the **atria to contract before the ventricles depolarize**. 4. The impulse then passes from the AV node through specialized conducing tissue known as the Bundle of His. The Bundle of His branches (left and right) within the septum that separates the ventricles and then into the Purkinje fiber system, which carry the impulse through the ventricular walls (QRS complex). This specialized conduction system ensures that the ventricles contract in a synchronized fashion and results in a contraction that begins at the apex (tip) of the heart. This is important because blood is ejected through the valves (pulmonic and aorta) that are located at the base of the heart (at the A-V junction).

Question 75

1. What is the stoichiometric formula for carbohydrates?

Answer 75

Carbohydrates can be represented by the stoichiometric formula **(CH₂O)n,** where n is the number of carbons in the molecule. Therefore, the ratio of carbon to hydrogen to oxygen is 1:2:1 in carbohydrate molecules. The origin of the term “carbohydrate” is based on its components: carbon (“carbo”) and water (“hydrate”). Carbohydrates are classified into three subtypes: monosaccharides, disaccharides, and polysaccharides.

Question 76

1. Describe the flow of blood through the heart 2. And the required thickness of the walls of the various parts

Answer 76

The **right side of the heart has a thin muscular wall and works at low pressures**. Contraction of the right ventricle (RV) pumps blood into the pulmonary circulation (lungs) where oxygen is taken up and carbon dioxide is eliminated. The **left side of the heart has a thicker muscular wall and works at higher pressures.** Contraction of the left ventricle (LV) pumps blood into the systemic circulation for delivery to the limbs and to all of the organs. The right atrium (RA) receives blood returning from the systemic circulation; the left atrium (LA) receives blood from the lungs (Figure 59). Total amount of blood circulating is ~5 liters/ minute

Question 77

What is the total amount of blood circulating in the body in a time interval?

Answer 77

The right side of the heart has a thin muscular wall and works at low pressures. Contraction of the right ventricle (RV) pumps blood into the pulmonary circulation (lungs) where oxygen is taken up and carbon dioxide is eliminated. The left side of the heart has a thicker muscular wall and works at higher pressures. Contraction of the left ventricle (LV) pumps blood into the systemic circulation for delivery to the limbs and to all of the organs. The right atrium (RA) receives blood returning from the systemic circulation; the left atrium (LA) receives blood from the lungs (Figure 59). **Total amount of blood circulating is ~5 liters/ minute**

Question 78

1. Where does blood enter and leave the heart? 2. What implications are there for contraction?

Answer 78

1. Note that blood enters and leaves the ventricles at the base (A-V junction). 2. That means that the ventricles must contract from the bottom (apex) upward to expel the blood from the base

Question 79

Draw a schematic of the heart showing flow, pumps and valves

Answer 79

[Four valves are embedded within the cardiac skeleton between the atria and ventricles.](http://padlet.com/davidofbuderim/gpf807lxm9f9) These valves respond passively to pressure gradients. The pulmonic and aortic valves open when the ventricles contract and close with relaxation. The pulmonic and aortic valves prevent back flow from the arteries into the relaxing ventricles. The AV valves (mitral and tricuspid) close once the ventricles fill. These two valves are closed during contraction of the ventricles and ejection of blood and therefore experience high pressures. To prevent the mitral and tricuspid valves from prolapse (being pushed into the atria) they are tethered to the ventricle wall via tendon like cords and the papillary muscles. The pulmonic and aortic valves do not have tendons to resist prolapse, instead they are semilunar valves (cup like in shape) which fill with blood when closed. These two valves are closed during relaxation and passive filling of the ventricles

Question 80

Draw a Left Ventricle Pressure Volume loop for a heartbeat - indicate what is happening at each stage

Answer 80

[Pressure-volume loop ABCD depicts changes in left ventricle in one beat.](http://padlet.com/davidofbuderim/gpf807lxm9f9) The ventricle fills between A-B. Interval B-C depicts isovolumic contraction. Interval C-D depicts ejection. Interval D-A depicts isovolumic relaxation

Question 81

1. What is cardiac output? 2. And how is it adjusted?

Answer 81

CARDIAC OUTPUT (CO) is the **volume of blood ejected by one ventricle in a period of time.** Cardiac output is one measure of the effectiveness of the heart as a pump. It dynamically adjusts by **changing either the heart rate or stroke volume or both**. **Cardiac output = stroke volume x heart rate** **CO= SV x HR** For an average resting heart rate of 70 beats per min (bpm) and a stroke volume of 70 mL per beat, the CO = ~ 5L/min. The average total volume of blood circulating in the body is ~ 5L. Therefore, each ventricle pumps all of the blood of the body through it in only one minute.

Question 82

Heart 1. What is Ejection Fraction =

Answer 82

EJECTION FRACTION (EF) describes the efficiency of the heart. It is Stroke volume(SV) divided by end diastolic volume (EDV) times 100. **EF (%) = SV/ EDV x 100** During strenuous exercise, CO can increase to 30-35 L/min. What parameter (stroke volume or heart rate) limits this increase in CO? [Answer: heart rate.] As heart rate increases, the time for contraction and relaxation of the cardiac muscle shorten; the filling time limits CO.

Question 83

Heart 1. What is preload? 2. and how is it increased?

Answer 83

**PRELOAD is the degree of stretch of the myocardium before contraction**. An **increase in venous return (filling) will increase preload** and thus increase the force of contraction. [Consider the P-V loop depicted in Figure 63.](http://padlet.com/davidofbuderim/gpf807lxm9f9) An increase in preload (filling) will move the EDV to the right along the X axis and increase the pressure generated (Y axis). The heart (depicted as ABCD) when filled to an EDV of 140 ml, generates a systolic pressure of 180 mmHg. The “red curved” line in Figure 63 depicts the force generated for each increase in EDV for this particular heart.

Question 84

1. What are the four factors that increase venous return to the heart?

Answer 84

Four factors can increase venous return (EDV): 1. Skeletal muscle pump in which contraction of leg muscles surrounding the veins aids in returning blood to the heart. 2. Respiratory pump in which deep breathing expands the chest and decreases the intra-thoracic cavity pressure. 3. Sympathetic nervous system activation leads to greater constriction of the arterial vessels and large veins which moves the blood to the heart. 4. Increase in blood volume as in blood doping.

Question 85

What is the electrical event on the ECG that precedes contraction of the atria?

Answer 85

P wave

Question 86

What is the electrical event on the ECG that precedes ventricular diastole?

Answer 86

T wave

Question 87

Ventricular repolarization in the human heart: A. begins in the atria and travels in the same direction as the depolarization wave. B. results from phase 2 of the fast action potential. C. is represented by the T wave on the electrocardiogram (ECG). D. is represented by the QRS complex on the electrocardiogram (ECG)

Answer 87

C. is represented by the T wave on the electrocardiogram (ECG).

Question 88

AV valves of the heart open and close because of: nervous impulses to papillary muscles. passive recoil of valves. changes in pressure in adjacent chambers. mechanical stretching of the fibers attached to the valves as the myocardium contracts and relaxes.

Answer 88

changes in pressure in adjacent chambers

Question 89

The region of the heart that normally has the highest rate of spontaneous action potentials is the: Purkinje fibers Atrioventricular (AV) node Bundle of HIS Sinoatrial (SA) node

Answer 89

Sinoatrial (SA) node

Question 90

In an electrocardiogram (ECG) , the atrio-ventricular (AV) conduction time is reflected in the: P-wave duration T-wave duration QT interval PR interval

Answer 90

PR interval

Question 91

Due to differences in opposing forces, there is usually a net _____ occurring at the arteriolar end of most capillaries coupled with net ___ at the venous end. absorption; filtration filtration; absorption

Answer 91

filtration; absorption

Question 92

Increasing venous return increases cardiac output by: decreasing end diastolic volume increasing the stroke volume decreasing the ejection fraction increasing heart rate

Answer 92

increasing the stroke volume

Question 93

Contrast the following: (i) velocity of blood flow in capillaries (ii) velocity of blood flow in aorta (ii) \> (i) (i) = or nearly = (ii) (i) \> (ii)

Answer 93

(ii) \> (i)

Question 94

Joan rose quickly from her bed to answer the front doorbell. In response to rising, her baroreceptors: decreased firing had no change in their firing rate increased firing

Answer 94

decreased firing

Question 95

What is the electrical event on the ECG that precedes ventricular diastole?

Answer 95

T wave

Question 96

What is the electrical event on the ECG that precedes contraction of the atria?

Answer 96

P wave

Question 97

What is the general method for determining molecular structure from the molecular formula? (Hint - counting electrons to give four numbers)

Answer 97

Available electrons = (valence electrons) Needed electrons = (to fill shells) Shared electrons = (needed - available) Bonds = (1/2 shared electrons) Draw the bonds and fill in lone pairs as required

Question 98

Molecular geometry 1. What is an electron domain? 2. How is it used?

Answer 98

single bond = 1 electron domain Lone pair = 1 electron domain Double bond = 1 electron domain Triple bond = 1 electron domain 2. Electrons in a single domain cannot be separated spatially =\> bond angles

Question 99

Periodic table 1. Name the elements 19-36

Answer 99

[table](http://www.ptable.com/)

Question 100

Periodic table 1. Name the first four Halogens

Answer 100

[table](http://www.ptable.com/)

Question 101

Periodic table 1. Name the first six Noble gases

Answer 101

[table](http://www.ptable.com/)