1. Does depolarization cause the muscle to become more or less likely to produce an action...

1. Does depolarization cause the muscle to become more or less likely to produce an action potential?

2. If blood travels from the left atrium to the left ventricle during ventricular diastole, why do you need a stage of the cardiac cycle known as atrial systole? What would happen to cardiac output if no atrial systole occurred?

Solutions

Expert Solution

1. Depolarization cause the muscle to become more likely to produce an action potential.

Explanation: - During depolarization phase in the muscle, there is opening of voltage gated sodium channels which causes the membrane potential to rise from -90mV to +35mV.

- During initial phase of depolarization, there is opening of few voltage gated sodium channels that changes the membrane potential from -90mV to threshold level of -55mV. If the membrane potential reaches the threshold level, it causes further opening of voltage gated sodium channels resulting in sodium influx which causes the depolarization and subsequent generation of action potential.

2. - During the beginning of cardiac cycle, both atria and ventricles are relaxing and blood flows from the vena cavae into the right atrium and via the two pairs of pulmonary veins into the left atrium from the lungs.

- During this diastolic phase, when both the atria and ventricles are relaxing, the atrioventricular valves (mitral valve and tricuspid valve) are open and blood flows continuously from the left atrium into the left ventricle and from the right atrium into the right ventricle. Almost 70-80% of ventricular filling occurs during this phase by passive filling of ventricles by the atria.

- During the atrial systole, atrial contraction occurs and remaining 20-30% blood ventricular filling occurs as the atrioventricular valves are opened at this stage. Thus, by active contraction of atria, the ventricles are filled completely with blood just prior to the beginning of ventricular systole.

- Thus, the atrial systole makes sure that the ventricular filling is completed prior to ventricular systole as 20-30% of ventricular filling occurs due to atrial contraction during atrial systole.

- If no atrial systole occurred then the ventricular filling during diastolic phase would remain incomplete which would decrease the cardiac output as stroke volume would be lowered.

Sydney Mullin answered 10 months ago

Next > < Previous

Related Solutions

An improvement in production technology will cause the production-possibilities curve to become less curved become more...

An improvement in production technology will cause the production-possibilities curve to become less curved become more curved shift outward shift inward 3. According to the concept of scarcity in economics wants will be fully satisfied sometime in the future there are no free goods free goods and scarce goods are the same the wants of society cannot be satisfied by the goods and services that can be produced from given resources 4. The production-possibilities curve shows All of the above...

Does a monopolistic competitor produce more or less output as compared to an efficient level of...

Does a monopolistic competitor produce more or less output as compared to an efficient level of production? Explain. What are the benefits and drawbacks of this? Should the government intervene to alter this?

1. Which of the following is more likely to cause urinary tract infections?

1. Which of the following is more likely to cause urinary tract infections? A) fimbriated strains of Escherichia coli B) non-fimbriated strains of Escherichia coli C) both fimbriated and non-fimbriated strains of Escherichia coli D) None of the answers are correct. 2. Capsules are particularly important for... A) making bacteria more vulnerable to host defense mechanisms. B) making bacteria less pathogenic. C) protecting bacteria from host defense mechanisms. D) allowing bacteria to become more phagocytic. 3. Pathogenicity is the...

1. What is an improvement action considered to be strong—meaning it is more likely to achieve...

1. What is an improvement action considered to be strong—meaning it is more likely to achieve patient safety improvement goals than weak or intermediate actions? Software enhancements Checklists for staff to follow Process double-checks Tangible involvement by leadership 2. What technique can be used to minimize cognitive overload for hospital caregivers? Test staff competencies at least annually. Eliminate committee assignments. Add patient care decision aids. Provide staff with adequate off-work intervals. 3. How long after an improvement project has ended...

Will a highly active muscle receive more, same or less oxygen than a resting muscle? Explain...

Will a highly active muscle receive more, same or less oxygen than a resting muscle? Explain the mechanism that may influence oxygen delivery to this muscle. Appropriate diagrams/graphs describing relevant hemoglobin properties are required in order to receive full credit.

Why is it likely that a macro economy that suffers from inflation will become less competitive...

Why is it likely that a macro economy that suffers from inflation will become less competitive internationally? (Use the unit labor cost concept to answer this question)

1. When interest rates are low, people are more likely to spend (or borrow) and less...

1. When interest rates are low, people are more likely to spend (or borrow) and less likely to save. This is consistent with the slopes of both the demand and supply in the loanable funds market. True False 2. The loanable funds market is a fundamental piece of a country's ability to grow and develop. True False 3. Which of the following would SHIFT the demand for loanable funds to the RIGHT (i.e. INCREASE). Select all that apply. Expectations that...

1. A. Compare the action potentials observed in cardiac muscle and skeletal muscle. B. Then describe...

1. A. Compare the action potentials observed in cardiac muscle and skeletal muscle. B. Then describe the action potential associated with the sinoatrial node. C. Describe the conduction system of the heart. 2.A. State the equations used to determine SV and CO. State the average values for all components. B. What happens to stroke volume when: i. ESV increases and decreases ii. EDV increases and decreases iii. increased sympathetic innervation iv. increased parasympathetic innervation v. afterload increases and decreases C....

QUESTION: The widely shared expectations of hard times ahead tend to cause investors to become less...

QUESTION: The widely shared expectations of hard times ahead tend to cause investors to become less risk-averse. True or False with an explanation Postings must be no less than 200 words

QUESTION: The widely shared expectations of hard times ahead tend to cause investors to become less...

QUESTION: The widely shared expectations of hard times ahead tend to cause investors to become less risk-averse. ANSWER OPTIONS: True False You need to specifically state IN THE SUBJECT LINE if the answer is TRUE or FALSE. EXAMPLES OF INADEQUATE RESPONSES: “I think the answer is False.” OR “The correct answer is “C.” Postings must be no less than 200 words in length to be considered. Any posting less than 200 words in length will not be reviewed.

Subjects