Week 7 - Cardiovascular - Heart and Vasculature, Electrical Events, Mechanical Events Flashcards
What are the components of the CV system?
Heart
Veins
Arteries
And capillaries
What are the two circulatory systems?
Systemic &
Pulmonary circulatory systems
Trace the pathway of the blood through the heart
- The R atrium receives blood from the
- Superior Vena Cava
- Inferior Vena Cava
- Coronary Sinus
- Separated from the L atrium by the interatrial Septum
- And exits via the tricuspid valve to the R ventricle which pumps blood through the pulmonary valve into the pulmonary trunk
- The R & L ventricle are separated by the interventricular septum
- Oxygenated blood enters the L atrium from the pulmonary veins and exists through the bicuspid (mitral) valve into the L ventricle
- This then pumps oxgenated blood through the aortic valve into the aorta
Trace the pathway of the blood through the body
- Veins bring blood to the R side of the heart
- Pulmonary arteries carry the blood to your lungs where it receive Oxygen
- Pulmonary veins move the Os rich blood to the L side of your heart
- The aorta (the main artery in your body) carries the blood from the L side of your heart to the rest of your body through many arteries
- Capillaries have thin walls that allow O2, nutrients, CO2 and waste to pass to and from tissue cells
- Veins then carry the blood back to your heart and the process begins again
What and where are the heart valves?
- Heart valves prevent backflow of blood within the heart
- The Atrioventricular Valves (AV) are the
Tricuspid valve on the R side
& the bicuspid (mitral) valve on the L
And lie b/w the atria and ventricles - The semilunar Valves (SL) are the:
Aortic valve at the entrance to the aorta
Pulmonary valve at the entrance to the pulmonary trunk
What do arteries do and what are they like?
strong & muscular to handle a large amount of force and pressure (but not volume) and carry oxygen-rich blood from your heart to your body.
They branch into smaller bodies called arterioles
Are aryeries and arterioles flexible and if so why?
They get bigger or smaller to help maintain your body’s blood pressure.
What are capillaries and what do they do?
tiny blood vessels have thin walls to allow for movement of substances
What are Venules and what do they do?
Veins begin as tiny vessels called venules and get gradually larger as they near your heart.
Venules receive blood from capillaries.
What are veins and what do they do?
- Unlike arteries, veins don’t carry highly pressurized blood,
- but they do have to carry large volumes of deoxygenated blood at low BP back to your heart.
- Therefore have Thin, less elastic walls
- and Most veins have valves to control blood flow and keep your blood flowing in one direction.
- About 75% of your blood is in your veins.
Label a diagram of the heart, including internal structures.
What is the pericardium, what are it’s layers and what do they do?
This is the membrane that surrounds and protects the heart and consists of:
Outer fibrous layer
Inner serous pericardium which is composed of:
Parietal layer
Visceral layer between which is:
The pericardial cavity which is filled with a few mm of pericardial fluid, reducing friction b/w the two membranes
What makes Cardiac Muscle unique?
- Usually contain a single centrally located nucleus
- Compared with skeletal muscle fibres they have:
more and LARGER mitochondria
Slightly smaller sarcoplasmic reticulum
And wider transverse tubules (located at Z discs) - They are connected end to end via intercalated discs
Desmosomes within which provide strength
And gap junctions allow muscle action potentials to conduct from one muscle fibre to it’s neighbours - Autorhythmic fibres form the conduction system allowing cardiac muscle fibres to spontaneously depolarise and generate action potentials
- Action potentials (those electrical impulses that send signals around your body) are created by a temporary shift (from negative to positive) in the neuron’s membrane potential caused by ions suddenly flowing in and out of the neuron.
What’s the difference between pacemaker and contractile cells?
Pacemaker cells set the HR
They are anatomically distinct from the contractile cells because they have no organized sarcomeres and therefore do not contribute to the contractile force of the heart.
They have an unstable resting membrane potential
What is the sequence of excitation?
The phases of an action potential in a ventricular contractile fibre are:
1. Rapid depolarisations
1. Long plateau
1. Repolarisation
What are the stages of an ECG?
P wave (atrial depolarisation)
A QRS complex (onset of ventricular depolarisation)
& a T wave (ventricular repolarisation)
What are P-Q and S-T intervals?
P-Q interval = conduction time from the beginning of atrial excitation to the beginning of ventricular excitation
The S-T segment, the time when ventricular contractile fibres are fully depolarised
What is Cardiac Output defined by?
Cardiac Output is the amount of blood ejected per minute by the left ventricle into the aorta (or by the R ventricle into the pulmonary trunk)
Calculated as :
CO (mL/ min) = Stroke Volume (SV) in mL/ beat x Heart Rate (HR) in beats/ min
SV is the amount of blood ejected by a ventricle during each stroke
