CHAPTER 12 The Cardiovascular System Regulation of Heart Activity The cardiac th
ID: 3505736 • Letter: C
Question
CHAPTER 12 The Cardiovascular System Regulation of Heart Activity The cardiac the autonomic nervous system center in the medulla obiongata of the brain can alter heart activity by way of nerve heart acivity by way of nerve fibers of Parasympathetic Sbers Parasympathetic ibers acetylcholine (ACh) travel by way of the vagus nerve (cranial nerve X) to the SA and AV noder w or speed2) the HR by the release of Sympathetic fbers also travel from the medula oblongata to the SA and Av in the myocardium of the ventricles. Sympathetic Sbers both HR and SV by the release of norepinephrine (NE) Blow or speed?) How does the medulia oblongata manage a halanc betuvren shese true aton.cmi branches? . At rest, which type of autonomic impulse is favored? During exercdse, which type of autonomic impulse is favored? How does the medulla oblongata lnow which sype of impus to fevor? Baroreceptors are sensitive to the stretch, or changes in pressure, that comes with changes in blood pressure. These baroreceptors are mainly located . When there is an increase in blood pressure, the baroreceptors signal the cardiac center in the medulla oblongata to send parasympathetic impulses to the SA node of the heart. Why? Cerebrum or hypothalamus may also send signals to the medulla oblongata so that HR can be altered in response to emotions, sensory stimuli. or conscious thought. Review Time! I. Provide a brief answer for each of the follewing questions about heart function 1. What is HR at rest? 2. What is SV at rest? 3. What is the average CO at rest? 4. Where is the cardiac center housed? 5. What do baroreceptors monitor? 6. What is Starling's law of the hean? 7. Relate Starling's law of the heart to bow exerase benefits the heart 8. What can the cardiac center modify? 9. What neurotransmitter and which autonomic impulse decreases HR? 10. What neurotransmitter and which autonomic impulse increase both HR and SV? 11. What cranial nerve travels to the SA and AV nodes to slow HR? What Roman numeral this cranial nerve?Explanation / Answer
1. The normal HR at rest in adults is usually 60 to 100 beats per min. A lower HR at rest generally implies better cardiovascular fitness and more efficient heart function.
2. SV is volume of blood ejected per beat from the ventricle and increases from approximately 1000 ml at rest upto 1700 ml or higher at maximal exercise.
3. For a person weighing 70kg, the average CO at rest would be 5 liters / minute.
4. It is housed in medulla oblongata.
5. The carotid sinus and aorta contain baroreceptors which constantly monitor blood pressure fluctuations.
6. The law states that the stroke volume of heart increases in response to a increase in the volume of blood in ventricles before contraction, when all other factors remain constant.
7. Increasing the force of contraction by exercise expels more blood from left ventricle, there by cardiac output increases when the preload increases.
8. The cardiac center affects changes to the heart rate by sending a nerve impulse to the SA node via sympathetic fibers and vagus nerve. It also increases the stroke volume of heart . These changes help to regulate cardiac output,there by sufficient amount of blood reaches tissues.
9. The vagus nerve release the neurotransmitter acetylcholine to decrese heart rate.
The parasympathetic nervous system decreases heart rate .
10. The sympathetic nerve release the neurotransmitter noradrenaline to increase heart rate.
The parasympathetic neurotransmitter acetylcholine and also calcium increases stroke volume by enhancing contractility.
11. Cranial nerve X or vagus nerve travels to SA node and AV node to slow heart rate by releasing acetylcholine.
Roman numeral representing this cranial nerve is X.