Cardiovascular System Flashcards
Heart Location
Behind Sternum, slightly left in medial cavity of thorax. The media stinum and surrounded by pericardium.
Heart Functions
Pumps blood around the body. The blood carries gases, nutrients, wastes, hormones and other things.
Epicardium
Outter heart wall layer, supports blood vessels and nerves.
Myocardium
Middle layer made up of muscles
Endocardium
Inner layer (squamous epithelium) presents smooth surface to blood flow.
Pericardium
Consists of outter parietal layer and inner visceral layer. The visceral pericardium is the same as the epicardium and covers surface of heart.
Pericardium functions
Protect heart, hold heart in position, prevent over filling of heart with blood, fluid in pericardial cavity provides friction free environment for contraction.
Pulmonary circulation
To lungs and back to heart.
Systemic circulation
To rest of body systems and back to heart
Four Heart chambers
Two Atria and Two Ventricles
Two sets of valves
Two semi lunar valves and two atrioventricular valves
Veins
Return blood to heart - received by atria
Ventricles
Pump blood away from heart. Arteries take blood away from heart.
Valves
Prevent back flow of blood
Which circulation requires higher pressure
Systemic circulation
which ventricle is more muscular and thicker
Left Ventricle
What is pulmonary circulation
Blood supplied to delicate lung tissue for gas exchange from right side of heart
What is systemic circulation
Blood supplied to other body systems from left side of body
Coronary arteries
Begin at base of Aorta inside aortic semilunar valve and supply the heart with oxygenated blood.
Cardiac Veins
Coronary sinus drains the deoxygenated blood from the cardiac veins into the right atrium and into the pulmonary circuit.
Where are Atrioventricular valves located
Between atria and ventricles
Where are semilunar valves located
Between ventricles and the arteries leaving the heart
Lubb signifies what?
Closure of AV valves
Dubb signifies what?
Closure of semilunar valves
Systole
Contraction of the heart
Diastole
Relaxation of the Heart
What is blood pressure
Pressure exerted by blood on the wall of a blood vessel
When is Systolic pressure measured
measured when left ventricle is contracting and expelling blood into Aorta
When is Diastolic pressure measured
Measured when the left ventricle is relaxing and blood is flowing into the peripheral blood vessels
What is a heart murmur
When leaky valves allow blood to flow backwards - creating a swishing sound or murmur.
What is stenosis
narrowing of arteries or valves
What causes heart contractions
Sinoatrial noda (sa) Atrioventricular node (av) Atrioventricular bundle left and right branches purkinje fibres
Depolarisation does what?
Causes contraction
Repolarisation does what?
Relax, get ready again for contraction
P Wave
sa node sends impulse
P R Interval
Impulse delayed at av node so ventricles can fill
QRS
Impulse passed to ventricles, Ventricles contract
T Wave
Ventricular repolarisation, ventricles getting ready for next contraction
ECG Cycle
atria have filled with blood, sa sends out impulse, atria depolarise and contract.
fibrous annulus
non conducting tissue separates atria from ventricles and the delay at the av node.
Sympathetic nerves
increase heart rate and the force of contraction
Parasympathetic nerve (vagus nerve)
decreases heart rate
Blood vessels
transport blood which carries gases, nutrients, wastes, hormones etc
Arteries
Take blood away from the heart.
Veins
Transport blood back to the heart
Large Arteries
Elastic Artery - allows expansion and contraction so blood can flow smoothly.
Muscular Artery - Distribute blood to parts of body
Small Arteries
Arteriole - Smooth muscle allows regulation of blood flow to capillaries.
Capillary - Vessles and connect arteries and veins. Sites of exchange.
Small Veins
Venule - Formed by capillaries joining together.
Vein - Formed by venues joining together.
How many layers to Arteries and Veins have?
3
Name the three layers (Tunicas)
Externia tunica - Outta layer - Connective tissue, collagen
Media tunica - Middle layer - Smooth muscle and elastic fibres
Intima tunica - Inner layer - simple squamous epithelia
Why are veins thinner than arteries?
Because blood pressure is lower
Capillaries
Blood flows thru capillaries and can be regulated according to need.
Why do Veins have valves?
Have valves to ensure the one way flow of blood back to heart. Prevent back flow.
What is a respiratory pump
when we breath in, pressure in thoracic cavity drops. Blood drawn towards thoracic cavity. When we breath out, pressure in thoracic cavity increases, veins are squeezed and blood pushed towards the heart.
What is a pulse
pressure wave felt in an artery. pressure wave is a result of left ventricle contracting - systolic pressure
What is mean arterial pressure (MAP)
Propels blood to the tissues.
How do we work out the pulse pressure?
Systolic - diastolic = answer
How do we work out the Mean Arterial Pressure (MAP)?
diastolic + 1/3 pulse pressure = answer
What is cardiac output
heart rate x stroke volume = cardiac output
what is stroke volume
Amount of blood ejected from ventricle during one contraction. Difference between EDV and ESV.
Is your BP higher or lower with the MORE blood your heart pumps out?
Higher
Increase Blood Volume = ?
Increase blood volume = increase BP
Decrease Blood Volume = ?
Decrease blood volume = decrease BP
What does Baroreceptor do?
Monitors blood pressure
what does Vasomotor do?
Allows veins to constrict or dilate.
What is peripheral resistance?
Vasoconstriction/dialation Thicker Blood (High haematocrit) Increased Length
What does Vasoconstriction do to blood pressure?
Increases BP
What does Vasodilation do to blood pressure?
Lowers BP
How do we reduce cardiac output?
Reduce heart rate and stroke volume
Blood vessles do what to reduce BP?
Dilate
What is Bainbridge Reflex?
Results in a increase in heart rate to ‘clear’ extra blood
What is mares law?
Inverse relationship between BP and HR. If BP too high, HR will decrease to compensate, if BP is too low, HR will increase to compensate.
What is Frank Starlings law?
The force of ventricular contraction is determined by the length of the cardiac muscle fibres.
What happens to BP during exercise?
Increased muscle contraction = increases skeletal muscle pump = increases blood flow back to heart.
Increased rate and depth of respiration = increases blood flow into the thoracic cavity (during inspiration) and blood entering the heart (during expiration).
Proprioceptor
Increased muscle activity is a stimulus and detected by receptors called Proprioceptors.
Chemoreceptor
Detects acidity increase/decrease. Chemoreceptor stimulate increase in cardiac output and respiratory rate to return body to homeostasis.
End diastolic volume (EDV)
Amount of blood in the ventricle at end of diastole. (relaxation and filling of ventricle)
End systolic volume (ESV)
Amount of blood in ventricle at end of systole. (After contraction and ‘emptying’ of ventricle)
Preload
Degree to which ventricular muscle is stretched just before contracting.
Afterload
Pressure ventricles must overcome to push blood through semilunar valves as ventricles are contracting.
How do we work out Cardiac Output?
Stroke Volume x Heart rate
