Heart And Circulatory System Flashcards
What are the 3 distinct layers of the heart wall?
Epicardium (outer)
Myocardium (middle)
Endocardium (inner)
What separates the right and left ventricle?
Thick interventricular septum
What separates the right and left atria?
Thin interatrial septum
The right atrium receives what type of blood and from where?
Deoxygenated/venous blood from the superior and inferior vena cava
When blood travel from the right atrium to right ventricle, which valve does it pass through?
Tricuspid valve
From the right atrium, which valve does the blood travel through and where does it end up?
Blood travels through tricuspid valve into right ventricle. Then travels through the pulmonary valve and enters the right and left pulmonary arteries. The deoxygenated blood then travels to the lungs for gas exchange.
Where does oxygenated blood enter the heart?
From the lungs, through the left and right pulmonary veins and into the left atrium
Which valve connects the left atrium and the left ventricle?
Mitral (bicuspid) valve - oxygenated blood travels through this
From the left ventricle, how does the oxygenated exit the heart?
Through the aortic semilunar valve, the aorta, and to the rest of the body
What is the cardiac cycle of deoxygenated blood through the heart?
- Enters through superior and inferior vena cava to the right atrium
- Deoxygenated blood leaves the right atrium through the tricuspid valve into the right ventricle
- Blood exists the right ventricle through the pulmonary valve and exists the heart through the left and right pulmonary arteries
- The deoxygenated blood then travels to the lungs for gas exchange.
What is the cardiac cycle of oxygenated blood through the heart?
- Enters the left atrium through the left and right pulmonary veins
- Oxygenated blood travels through the mitral (bicuspid) valve into the left ventricle
- Exists the left ventricle through the aortic semilunar valve into aorta.
- The oxygenated blood then travels to the rest of the body.
What is the period of diastole in the cardiac cycle
A period of relaxation in the cardiac cycle when the heart fills with blood.
80% of blood flows directly through the atria into the ventricles before contraction.
What is the systole period in the cardiac cycle?
The phase of contraction of the hearts ventricles, forcing blood out of the heart.
Which valve will close during systole of the left ventricle?
Mitral valve will close to prevent back flow into left atrium
Which valve will close during systole of the right ventricle?
Tricuspid valve will close to prevent back flow into right atrium
Which ventricle has thicker walls and why?
Left ventricle due to the increased pressure required to pump blood to rest of body.
Which valve prevents back flow from the aorta into the left ventricle?
Aortic semilunar valve
What is pericarditis?
Inflammation of the pericardial sac
How many pints of blood does the heart pump 24/7?
8 pints
What encloses and protects the heart and forms the wall of the pericardial cavity which contains the pericardial fluid?
Pericardial sac / Parietal pericardium
What is the parietal pericardium composed of?
Outer fibrous and inner serous layer
Which layer of the parietal pericardium secretes the pericardial fluid and what is its function
Inner serous layer
Pericardial fluid acts to reduce friction as the heart beats
Which layer of the heart wall is responsible for contraction?
Myocardium; thick middle layer, composed of thick cardiac muscle
What is endocarditis?
Inflammation of the endocardium (smooth inner layer of the wall, lining of heart and internal structures.
What can endocarditis be triggered by?
Very rare; but bacteria can enter the blood stream through the mouth and then end up in the heart
What connects cardiac muscle cells together?
Intercalated discs
What do intercalated discs consist of and what are their functions?
- Fascia adherens and demosomes; hold cardiac muscle cells end to end.
- Gap junctions; allow ions to pass between cardiac muscle cells, transmitting nerve impulses.
What do grooved depressions indicate on the surface of the heart?
Partitions between the 4 chambers.
Also contain the cardiac vessels that supply blood to heart wall.
In which direction does the blood flow in the veins?
Blood flows towards the heart
In which direction does the blood flow within the arteries?
Away from the heart.
What are the components of the conduction system of the heart?
Sinoatrial node
Atrioventricular node
Bundle of Hip
Purkinje fibres
Where is the Sinoatrial node located?
Right atrium near the superior vena cava opening
During diastole what does the Sinoatrial node exhibit?
Spontaneous depolarisation (pacemaker potential)
Where does each heartbeat begin?
Sinoatrial (SA) node (hearts pacemaker)
What does a wave of depolarisation result in?
Atrial systole
This converges at the atrioventricular (AV) node.
Which node delays the electrical impulses, for how long and why?
Atrioventricular (AV) node.
0.1-0.2 seconds.
To give the atria time to fully empty the ventricles.
Where conducts the impulses from the atrioventricular node and what are they?
Bundle of His.
Specialised muscle fibres that conduct electrical impulses from the AV node.
What are the specialised nerve cells within the heart and what is the main function?
Purkinje fibres.
Sends electrical impulse received from the AV node to the bundle of His, to the ventricles. This coordinates contraction of the ventricles, ventricular systole.
What is pulmonary circulation?
Transportation of deoxygenated blood from right ventricle, out the pulmonary valve and left and right arteries, to lungs to be oxygenated, back to the left atrium through the left and right pulmonary veins.
- pulmonary truck (arteries, veins, capillaries)
What is systemic circulation?
Transportation of oxygenated blood from the left ventricle through the aortic valve into the aorta, the oxygenated blood transports and delivers to the body and collects carbon dioxide. This this travels back to the heart through the superior and inferior vena cava into the right atrium.
What happens in the capillaries?
Rapid rate of gas exchange between blood and tissues; oxygen, nutrients, waste products.
What is the primary role of platelets in blood?
Clotting mechanisms
What’s the primary role of red blood cells?
Transport oxygen
What does blood pressure measure?
The force exerted by circulating blood on vessel walls
What type of vessel carries oxygenated blood away from heart?
Arteries
What type of vessel carries deoxygenated blood to the heart?
Veins
What is the hearts own circulation known as?
Coronary circulation
What does the cardivascular system control?
Homeostasis
Why is pulmonary circulation unnecessary in utero?
Foetal blood is oxygenated from the placenta
What serves as the connection between the foetus and placenta in foetal circulation?
Umbilical cord
What is venous blood?
Deoxygenated
In foetus circulation, the venous blood returning to the right atrium is deflected into the left atrium through what?
Foramen Ovale
In foetus circulation, the blood in the left ventricle is diverted away from the pulmonary arteries, to the aorta, through the what?
Ductus arteriosus
What are the 5 types of blood vessels
Arteries
Arterioles
Capillaries
Venules
Veins
Function and structure of arteries
- Transport oxygenated blood under high pressure to tissues within body.
- Thin elastic muscular walls.
- Strong muscular walls to withstand pressure.
Function of arterioles
Last small branch of artery system.
Act as control valves to release blood into capillaries.
Function and structure of capillaries
- Exchange nutrients, hormones, waste, oxygen, electrolytes between blood and tissues.
- Smallest and most abundant in body.
- Walls are endothelium 1 cell layer thick.
Function of venules
Collect blood from capillaries
Function and structure of veins
- Transports blood from tissues back to heart and act as reservoir.
- Contains valves to prevent back-flow/pooling.
- Carry deoxygenated blood back to heart.
- Rely on the skeletal muscle and respiratory pump.
- Less muscular and elastic compared to arteries but still same 3 layers.
What determines the blood flow through capillaries?
Precapillary sphincter muscles and the constriction or dilation of arteries or arterioles.
3 types of capillaries
Continuous - no perforations
Fenestrated - small perforations
Discontinuous - large openings
What is the blood brain barrier?
Boundary between circulating blood and the brain
Functions of the blood brain barrier?
Highly selective and protects the brain from foreign substances and maintains constant environment for brain.
How are large molecules, immune cells, bacteria and viruses prevented from passing the blood brain barrier?
Brain capillaries are not fenestrated and their endothelial cells are tightly packed.
