6.2 The Blood systems Flashcards
What are the layers of arteries?
Narrow central lumen
Endothelium
Thick inner layer of muscle and elastin
Thick outer layer of collagen
What are the three types of capillaries?
Continuous
Fenestrated (porous)
Sinusoid (intercellular gaps and incomplete base membrane)
Where can fenestrated capillaries be found?
Intestine and kidney for absorption
Where can sinusoid capillaries be found?
Liver for absorption of larger molecules
What are the layers of a vein?
Wide lumen
Endothelium
Thin layer of muscle and elastin
Think outer layer of collagen
How do vein valves open?
Skeletal muscle contractions put pressure on the vein, forcing open the valves
What is the name of the left atrioventricular (AV) valve?
Bicuspid valve
What is the name of the right atrioventricular (AV) valve?
Tricuspid valve
What is the name of the left semilunar valve?
Aortic valve
What is the name of the right semilunar valve?
Pulmonary valve
What does “heart contractions are myogenic” mean?
They rise from within
Where is the Sinoatrial node (SA node)?
Right atrium
What is the function of the SA node?
Normal sinus rhythm
What is normal sinus rhythm?
60-100bpm
If the SA node fails what takes over?
AV (atrioventricular) node at 40-60bpm
If the AV node fails what takes over?
His bundle at 30-40 bpm
What does sinus rhtythm mean?
Cardiac cells contracting in unison
What does fibrillation mean?
Cardiac cells contracting independently (bad)
Describe one full cardiac contraction
SA node sends impulse stimulating the contraction of the myocardium causing the atria to contract
AV node triggered and sends signals down the septum to the nerve bundle (Bundle of His)
The Bundle of His innervated the Purkinje fibres and there is a ventricular contraction
What are the myocardium?
Cardiac muscle cells
What does the sympathetic nerve cause?
Increase HR
What does the parasympathetic nerve cause?
Decrease HR
What is the function of adrenaline?
Increase HR
Where is adrenaline produced?
Adrenal glands
What causes the lub sound?
Closing of the AV valves
What causes the dub sound?
Closing of the semilunar valves
What is systole?
Contraction of a heart chamber
What is diastole?
Relaxation of a heart chamber
What may happen if a thrombus becomes dislodged from an atherosclerotic plaque?
It may become embolus and block smaller arterioles
