circulatory system #2 Flashcards
what are the three main types of blood vessels?
- arteries
- capillaries
- veins
what are arteries?
- Thick elastic tubes lined with smooth muscle
- carry oxygen rich blood away from the heart
what do arteries branch into?
arterioles
what are capillaries?
- tiny vessels that connect arterioles and venules
- they carry gases, nutrients, and wastes
what are veins?
- thinner, non-elastic tubes
- they carry deoxygenated blood to the heart
what do veins branch into?
venules
does the heart need external nerve stimulation to contract?
no
what type of working muscle is the heart?
myogenic muscle
what is tachycardia?
heart beating at 100bpm or more at rest
what type of stimulation slows the heart?
parasympathetic stimulation
where does electrical stimulation originate?
in the heart
is the heart dependent on the brain?
no
what does “SA” stand for?
sinoatrial
what does the Sinoatrial (SA) node do?
- “pacemaker”
- sends out an electrical signal that spreads over the two atria and they contract simultaneously
where is the SA node located?
in the wall of the right atrium
what do purkinje fibres do?
they cause the left and right ventricles to contract
what is the order of the transmission of contraction?
- SA node sends out electrical stimulus to cause atria to contract
- impulse reaches the AV node
- impulse pauses
- impulse then passes through the “Bundle of His”
- impulse reaches left and right bundle branches
- impulse continues through the purkinje fibres causing the ventricles to contract from the bottom up forcing blood to the pulmonary arteries and aorta
what causes the ventricles to contract?
impulse reaching the purkinje fibres
what is the flow of blood through the blood pathway?
heart -> aorta -> arterioles -> capillaries -> venules -> veins -> vena cava -> heart -> lungs
what is arterial flow?
- artery relaxing and contracting as blood is pumped out of the heart
what is pulse?
change in diameter of the arteries following heart contractions
what controls blood flow from arterioles to capillaries?
pre-capillary sphincters
when do arterioles open?
when cells in an area require blood
how many square km of capillaries are in our bodies?
6.3km squared
where is the flow of blood slowest?
in capillaries