HK 3810 Package 1 notes.docx

Decrease spontaneous depolarization rat takes longer

Info icon This preview shows pages 6–8. Sign up to view the full content.

View Full Document Right Arrow Icon
decrease spontaneous depolarization rat takes longer to take to threshold decrease HR o SNS releases NE onto SA/AV node increase Na+ leak rate decrease time to threshold generate more APs/min increase spontaneous depolarization rate increase HR Extrinsic control – hormonal control o SNS stimulates adrenal glands to release EPI/NE onto SA/AV node increase Na+ leak rate decrease time to threshold --< increase spontaneous depolarization rate increase HR Negative effect of HR on CO: increase HR decrease duration of diastole decrease filling time decrease preload (EDV) decrease SV decrease CO
Image of page 6

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
HK 3810 Package 1 Positive effect of HR on CO: increase HR increase contractility (staircase) decrease ESV increase SV increase CO Unknown effect: beat-per-beat argument: increase HR increase CO increase afterload decrease SV decrease CO At low HR, there are regions where positive effects outweigh negative effects At high HR, there are regions where negative effects outweigh positive effects Where is CO going? (left ventricle CO) At the level of the aorta, we have the highest pressure (100 mmHg which is from contracting ventricular myocytes) If we want flow from one end of the system to the other, there needs to be a pressure from large arteries to small arteries, arterioles, veins Veins flow right into right atria, so it has to have pressure that is lower than 7 mmHg (approx. 0 mmHg) Venous pressure = MCFP Compartment characteristics are different Large arteries – small changes in volume results in large changes in pressure due to the fact that it is stiff, rigid, non-compliant bc it is used for transport Veins – large changes in volume results in small changes in pressure due to the fact that it is very compliant and elastic bc it is used for storage Nature of the wall of vessel will determine the behaviour of vessel Blood vessels Have very different wall characteristics All have variations of these layers Capillaries only have endothelial cells and basement layer Aorta has thick media cells with many muscle cells In media, you can primarily find SNS Adventitia is made up of SNS, macrophages and fibroblasts; it is the outermost layer Aortic/arterial compartment CO of the heart dictates volume into the aorta Resistance arterioles dictate volume out of the aorta If CO increase increase volume into aorta and volume out of the aorta is constant (arterioles did not change) volume in aorta increase increase pressure in the aorta increase MAP Changing CO depends on EDV, ESV and HR o Increase SNS output to ventricular myocytes increase contractility (not rate) decrease ESV increase SV increase CO increase MAP Arterioles Resistance arterioles have the ability to increase or decrease flow out of the aorta
Image of page 7
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern