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United States (324,088)
BISC306 (101)
Cain William (101)
Lecture 25

BISC306 Lecture 25: Lecture 25

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Biological Sciences
Cain William

Lecture XXV I. Control of cardiovascular system a. By controlling heart a.i. SV a.ii.HR b. By controlling blood vessels b.i. Vasoconstriction/dilation c. Cardiac muscle or vascular smooth muscle is controlled by CNS d. Medullary cardiovascular center d.i. Not a CPG d.ii.Controls speed and contractility d.iii.Pattern is controlled by heart itself e. Where would you measure BP to control cardiovascular system e.i. In big arteries; the pressure the heart is putting on the arteries e.ii.Central arteriole pressure  on left side e.iii.Arterial baroreceptors send information back to the medullary cardiovascular center, and compares to set point, and decides whether to increase or decrease e.iv. There are other receptors as well II. High pressure baroreceptors are found in systemic arteries a. Stretch receptors send information back by the X nerve (vagus) and IX nerve b. Carotid sinus – place where you monitor pressure; right next to the heart III. Increased stretch causes increased firing of high pressure baroreceptors a. Measure AP’s on those two nerves and how they coordinated with BP b. As pressure goes up, AP goes up IV. High pressure baroreceptors and BP regulation a. If pressure goes up, stretches baroreceptors, goes back to medulla, autonomic NS affects heart, vessels, and adrenal medulla to decrease cardiac output to lower blood pressure; also changes resistance a.i. Decreased HR and vasodilation decreases V. Atrial receptors (low pressure receptors) a. Respond mainly to stretch caused by venous return to the heart. Act in effect as volume receptors a.i. Tells you about venous return and volume a.ii.Kidney regulates blood volume, and pressure through the volume b. B fibers located mainly in the veins (vena cava) entering the right atrium and increase firing in response to rising venous pressure. Stimulation raises the heart rate. It also causes increased urine output c. Atrial myocytes respond to increased stretch by release of the hormone called atrial natriuretic peptide (ANP) which causes vasodilation (makes easier to pump blood out); this causes increased urine output which effectively lowers blood volume VI. Chemoreceptors and cardiac output a. Blood has to be delivering nutrients and picking up waste b. Rate limiting factor is oxygen delivery; so really aware of how much oxygen you have in your blood c. Plasma concentrations of oxygen (P ), carbon dioxide (P ), and pH are O2 CO2 important regulators of cardiac output and respiration d. As oxygen goes down, have to pump more blood to pick up more oxygen e. Peripheral receptors located in carotid and aortic bodies to detect oxygen levels; located right where baroreceptors are; right where blood has just come from the lungs f. Central chemoreceptors that sense oxygen are located in the medulla VII. When animal is not breathing (under water) a. Oxygen levels go down  don’t want to increase cardiac output b. Reflex doesn’t work when not breathing c. Medulla responds the opposite way  decreased HR and vasoconstriction; this decreases cardiac output VIII. Same scenario but when animal is breathing a. Receptors know you’re breathing and changes the response completely b. Oxygen levels go down  increase HR, vasoconstriction  increases cardiac output IX. How do you determine which tissues get the oxygen  determined by the tissue itself X. Control of capillary blood flow in systemic circulation a. Blood flow to the heart and CNS get the #1 priority at all times b. Primarily regulated at the level of the arteriole c. Neural control – not local control c.i.Primarily sympathetic and vasoconstrictive c.ii.Some parasympathetic nerve endings cause vasodilation d. Hormonal control by circulating epinephrine – still not local control e. Local control e.i.Terms
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