Lecture 11 - Bio 2A03 L11 Lecture 11 Circulation V Venuoles...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Bio 2A03 – L11 Lecture 11 – Circulation V Venuoles and Veins 1. Return blood back to the heart (via vena cava – vessel that enters heart) and act as a volume reservoir (50-80% of blood volume – vasoconst or dil) 2. Thin-walled and highly compliant vessels to accommodate large volumes for small changes in pressure (“capacitance vessels”) 3. Necessary force to provide by ∆P between peripheral veins (10-15 mmHg) and right atrium( ~0 mmHg) adequate because of low R of veins 4. Veins also have one –way valves that ensure movement towards the heart 5. Venous pressure depends on volume of blood, nerve, hormonal and paracrine regulation 1. Respiratory Pump – negative pressure draws blood to heart 2. Skeletal Pump – when muscles contract, squeeze veins (increase pressure) and blood pushed toward heart (↑ blood flow) 6. Venous return has a major effect of volume ejected by the heart = stroke volume 7. Heart always pumps out all blood it receives 8. Venous return helps regulate stroke volume 1. Way cardiac output and MAP will be regulated 1. One way valves – lower valve closes and upper valve opens 1. When skeletal muscle relaxes valve closes to prevent backflow of blood 2. Imp during exercise 3. Veins – low resistance, small P diff between ventricles and atrium
Background image of page 1

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

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/26/2011 for the course BIOLOGY 2a03 taught by Professor Nurse during the Spring '10 term at McMaster University.

Page1 / 6

Lecture 11 - Bio 2A03 L11 Lecture 11 Circulation V Venuoles...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online