Cardiovascular Flashcards
Pulsatile Pump
Heart
Not continuous
Elastic Artery
many thin sheets of elastin in the middle tunic
Function of Muscular Arteries
bulk distribute blood around the body at high pressure
How is rate of blood flow adjusted?
using smooth muscle to vary the radius of the vessel
- a small change in radius has a large effect on flow rate
(flow is proportional to the fourth power of the radius)
Muscular Artery
many layers of circular smooth muscle wrapped around the vessel in the middle tunic
What are the three sections of the wall of a muscular artery?
Outer tunic
Middle tunic (with smooth muscle)
Inner tunic
Function of an Arteriole
control blood flow into capillary beds
Structure of Arteriole
between one and three layers of circular smooth muscle wrapped around the vessel in the middle tunic
Function of Capillary
tiny vessels which are thin-walled to allow exchange of gases, nutrients and wastes between blood and surrounding tissue fluid
Structure of Capillaries
leaky vessels, plasma escapes
single layer of endothelium/ no smooth muscle and no connective tissue (cannot change diameter)
Function of Venule
low-pressure vessels which drain capillary beds.
During infection they are the site where white blood cells leave the blood circulation to attack bacteria in the tissue alongside
Veins
thin-walled / low-pressure
stretch easily
act as reservoir to store blood
Coronary Arteries
Arise from the aorta just down from the aortic valve
Cardiac Output =
Heart Rate x Stroke Volume
CO
Cardiac Output
the volume of blood ejected into the aorta per minute
Venous Return
the volume of blood returning to the heart from the vasculature every minute and it is linked to cardiac output
What is Heart Rate controlled by?
SA Node
Stroke Volume
The volume of blood pumped out of the left ventricle of the heart during each systolic cardiac contraction
End-diastolic volume
is the amount of blood that is in the ventricles before the heart contracts.
End-systolic volume (ESV)
The volume of blood in the left or right ventricle at the end of the systolic ejection phase immediately before the beginning of diastole or ventricular filling.
Frank Starling law of the heart?
The stroke volume of the left ventricle will increase as volume increases, due to the myocyte stretch causing a more forceful systolic contraction
Preload
The initial stretching of the cardiac muscle cells prior to contraction
- leads to an increase in EDV and an increase stroke volume
-mitral valve closes
Afterload
The amount of pressure that the heart needs to exert to eject the blood during ventricular contraction
Hypertension
higher resting BP
Intropy
the performance of the heart at a given preload and afterkiad
Baroreceptors
sensing pressure
respond to stretch in the atrial wall
vagus nerve
parasympathetic
