circulation and gas exchange
Post on 31-Dec-2015
25 Views
Preview:
DESCRIPTION
TRANSCRIPT
Internal Transport
Gastrovascular cavity makes circulatory system unnecessary
Open and closed circulatory systems What are the limits an open circulatory
system places on an organism? What is the difference between an
artery and a vein? Arteries carry blood away from the
heart Veins bring blood back to the heart
Why do veins have valves and arteries do not? Veins move blood against gravity without
benefit of the heart contraction Blood flow:
Heart arteries arterioles capillaries venules veins heart
Which chamber of the heart receives the blood?
Which chamber pumps the blood?
Vertebrate Circulatory Evolution
Fish have 2 chambered heart, one beat circuit: 1 atrium 1 ventricle
Amphibians have 3 chambered heart: 2 atria 1 ventricle
Reptiles have 3 – 4 chambered heart: Septum keeps 2 parts of ventricles separate
Mammals and birds have 4 chambered heart!
The Heart Cardiac muscle Atria have thin walls Ventricles have thick and powerful walls Systole = ventricular contraction blood is
pumped Diastole = ventricular filling Lub dub = heart sounds opening and closing
of the valves Lub = contraction of ventricles (AV closing) Dub = blood recoiling against Semi Lunar valves
Heart murmur = valve defect
CO = cardiac output ; Volume of blood pumped/ minute
SV = stroke volume: Amount of blood pumped by L
ventricle/contraction CO is effected by heart rate and SV Myogenic heart can regulate its own rhythm SA node is the pacemaker of the heart
Arteries and Veins
How do differences between arteries and veins reflect their different functions?
Artery wall is very thick to absorb pulsation from heart
Veins are wider in diameter and are not as muscular
Veins have valves Capillaries have only single layer of
endothelium
Blood Pressure
The force that blood exerts against vessel walls
BP is greater in arteries than veins Pulse is measure of BP Exact BP is measured as systolic/diastolic
pressures Constricted blood vessels have higher BP
than dilated vessels In veins heart has little effect on BP How, then does blood move in veins?
Lymphatic System
Lymphatic system returns lost blood to circulatory system
Lymph nodes filter the lymph Help fight infection
Why do endotherms have the greatest need for a 4 chambered heart?
Birds and mammals show convergent evolution of 4 chambered heart!
top related