Cardiovascular System Flashcards
When does the heart form?
around week 10 of embryonic development
What are the 4 chambers of the heart?
- right and left ventricles (lower)
- right and left atria (upper)
How does blood flow through the heart?
- deoxygenated blood flows from the body into the right atrium which pushes it to the right ventricle which pumps it out to the lungs
- oxygenated blood returns from the lungs to the left atrium which pushes it into the left ventricle where it is pumped back out to the body via the pulmonary arteries
Which part of the right atrium is rough?
the part closest to the auricle (embryonic part)
What does the tricuspid valve allow?
a single direction of blood flow from the right atrium to the right ventricle
What are the trabeculae carneae?
muscular ridges that help with blood flow by preventing the suction that would occur if the internal surfaces of the ventricular wall were smooth
What are the chordae tendineae?
thin, cord-like tendons that connect the AV valves to the papillary muscles to prevent the valves from inverting into the atria during ventricular contraction (systlole)
What do the papillary muscles do?
prevent atrioventricular valves from opening during systole
What does the bicuspid (mitral) valve allow?
oxygenated blood to travel from the left atrium into the left ventricle
What are the alternate periods of the cardiac cycle?
- systole (contraction and emptying)
- diastole (relaxation and filling)
What happens during atrial contraction and ventricular relaxation?
blood fills the ventricles
What happens during ventricular contraction?
blood is ejected from the ventricles to the outflow tracts (aorta and pulmonary trunk)
What do the 4 valves of the heart do?
control the flow of blood through the heart by opening and closing the chambers in a coordinated sequence
What are the 2 valves between the atria and ventricles?
tricuspid and bicuspid (mitral)
Which valves ensure blood exits the heart correctly?
aortic and pulmonary semilunar
Which of the 4 heart valves carry oxygenated and deoxygenated blood?
- pulmonary (deoxygenated)
- aorta (oxygenated)
- tricuspid (deoxygenated)
- bicuspid (oxygenated)
What does contraction of the papillary muscles do?
pull the AV valves down and prevent blood from returning into the atria
What are arteries that supply the heart branches of?
the ascending thoracic aorta
What is the pathway of deoxygenated blood?
- pools in the great, middle and small cardiac vein
- flows into the coronary sinus
- flows into the right atrium
What is the pericardium?
a protective, fluid-filled sac that surrounds the heart with a fibrous and serous layer
What are the functions of the pericardium?
- position the heart between the lungs in the chest cavity
- lubricate the surface of the heart to reduce friction when beating
- prevent overfilling
What is the order of conduction in the heart?
electrical signals originate in the SA node then travel from the atria to the ventricles and pass through the AV node
What is the bundle of His?
an elongated segment connecting the AV node and the left and right bundle branches of the septal crest
What are the 5 steps of conduction in the heart?
- atrial depolarisation initiated by the SA node
- delay at the AV node to allow time for the atria to contract completely and the blood to fully fill the ventricles
- ventricle depolarisation
- atrial repolarisation
- ventricular repolarisation
What happens during ventricle depolarisation?
- electrical impulse travels down the AV bundle to the apex of the heart
- moves upwards on the walls of the ventricles to begin depolarisation
- this triggers ventricular contraction from the bottom to allow ejection of blood upwards into the aorta and pulmonary trunk
What is the sympathetic innervation to the heart?
adrenaline/noradrenaline acts on β-adrenergic receptors to increase heart rate, heart contraction and cause vasoconstriction
What is the parasympathetic innervation to the heart?
ACh acts on M2 muscarinic receptors to decrease heart rate and contraction and cause vasodilation
What are beta blockers used for?
hypertension and increased heart rate e.g. atrial fibrillation
How do beta blockers work?
they bind to beta-receptors on the heart and vessels to prevent adrenaline/noradrenaline from binding
What is the order of organisation in the heart wall from internal to external?
- endocardium
- myocardium
- epicardium
- pericardial cavity
- parietal pericardium
- fibrous pericardium
What do desmosomes do?
anchor adjacent cells to prevent them from separating from each other during contraction
What is a gap junction?
a pathway which allows ions to pass from one cell to another, allowing electrical impulses to spread throughout the myocardium
What causes a functional syncytium?
gap junctions as they allow contraction as one unit
How do ultrasounds work?
sound waves bounce off tissues, organs or structures which creates echoes that are captured on a screen in real time
Describe arteries (function, appearance, wall thickness, valves, pulsation and direction of blood flow)
- function - transport oxygenated blood
- rounded shape
- thicker walls to sustain pulsatile pressure
- no valves
- pulsation present
- blood flows away from the heart
Describe veins (function, appearance, wall thickness, valves, pulsation and direction of blood flow)
- function - transport deoxygenated blood
- irregular shape
- thinner walls since no need to sustain pulsatile pressure
- valves to allow one way direction
- no pulsation
- blood flows towards the heart
What are the 3 layers of blood vessels?
- tunica intima
- tunica media
- tunica adventitia
What is the tunica intima?
endothelial lining of the lumen formed by simple squamous epithelium that contains basement membrane and loose connective tissue to support endothelial lining and also contains elastic lamina
What does the tunica media contain?
- smooth muscle responsible for vasodilation and vasoconstriction (depending on ANS input)
- external elastic lamina
What does the tunica adventitia contain?
- own blood supply from its own vessels termed as vasa vasorum
- collagen providing structural support and protection to the vessel
How can venous blood travel from superficial veins to deep veins?
via perforator veins
What is a portal system?
a connection in which blood passes through two sets of capillary systems before returning to the heart
What is the first and second capillary system?
- first - digestive organs
- second - liver
Where does the hepatic portal vein carry blood?
to the liver from the intestines, spleen, pancreas, and gallbladder
