circulation Flashcards
Open circulatory system
Blood may be only partially or not at all confined to blood vessels. eg insects
Closed circulatory system
Blood completely confined to blood vessels. eg squid
Three basic components of the circulatory system
A transport system(blood), a set of tubes(blood vessels) and a muscular pump(heart)
Open circulatory system in insects
as heart relaxes it draws haemolymph into the circulatory system through valved pores called ostia.
Blood vessels
arteries: from heart to arterioles to capillaries
veins: from venules to capillaries to heart
capillaries: exchange of gases and nutrients
single circulation in fish
two main heart chambers: one ventricle and one atrium
Blood pressure drops as it flows through the 2 capillary beds. this limits the aerobic metabolic rate of fish.
In double circulation how often does the blood pass through the heart?
Passes through the heart twice per circuit
systole
contraction phase
diastole
relaxation phase
What does the cardiac output depend on
heart rate= pulse
stroke volume (amount pumped by left ventricle per contraction)
what maintains the beat of the heart?
the sinoatrial and atrioventricular nodes working in synchrony
Why do arteries have thicker walls than veins?
To help maintain blood pressure between heart contractions
why is there slow blood flow in capillaries?
allows exchange of gases and nutrients
What moves blood through veins
muscle movements
Atherosclerosis
caused by the buildup of low-density lipoproteins(bad cholesterol) within arteries
