Structure of the heart Flashcards
What are the three layers of the heart (from outermost to innermost)
- Pericardium
- Myocardium
- Endocardium
What is the function of the pericardium
To prevent the heart from over stretching and protect it from structural damage
What is the inner layer of the pericardium composed of
Two serous membranes
What do the serous membranes in the inner layer of the pericardium produce and what is the function of this
Serous fluid between the two layers to provide lubrication
What are the two layers of the pericardium
The parietal pericardium (outer)
The visceral pericardium (Inner)
What does the serous fluid between the two layers of the pericardium do
permits the membranes to move against each other without friction
What is the myocardium made of
thin filaments of actin and thick filaments of myosin (muscular layer)
What is the endocardium made of
single layer of epithelial cells continuous with the innermost layer of the blood vessels
What are the trabeculae cardneae
Rough muscle bundles that line the anterior and inferior walls of the right ventricle, lower two thirds of the septum and inferior walls of the right ventricle. Involved in contraction of the heart.
What helps the cardiac muscle to be fatigue resistant
The cells in the cardiac muscle contain a large number of mitochondria
what is cardiac muscle innervated through
The autonomic nervous system
What are the 4 chambers of the heart
The left and right atrium and the left and right ventricle
What is the pathway of blood flow through the heart
Superior and inferior vena cava sends deoxygenated blood from the body to the right atrium.
Blood flows through the tricuspid valve into the right ventricle.
Blood is pumped through the pulmonary valve into the pulmonary trunk which divides into right and left pulmonary arteries.
Deoxygenated blood is taken into the lung for gaseous exchange.
Capillaries bring oxygenated blood into pulmonary venules and pulmonary veins.
Veins empty into the left atrium of the heart where the blood is pumped through the bicuspid valve to the left ventricle.
From the left ventricle, blood is pumped through the aortic valve into the aorta and then out to the body through the arteries, arterioles and capillaries.
What divides the left and right sides of the heart.
The septum
What is the role of the valves of the heart
Ensure blood flows in one direction, from the atria to the ventricles, while preventing back flow from the ventricles into the atria
What are the valves between the atria and ventricles
atrioventricular valves
What are the two atrioventricular valves
tricuspid (right side of heart) bicuspid (left side of heart)
What are the valves at the entrances to the major arteries from the heart
semilunar valves (pulmonary valve and aortic valve)
What is the function of the valves during blood flow through the heart
When the ventricles relax, the semilunar valves close and the atrioventricular valves open, allowing blood to move from the atria into the ventricles.
Once the ventricles contract, the atrioventricular valves close and the semilunar valves open, ensuring that blood moves from ventricles to pulmonary trunk and aorta and not back into atria.
What circulatory system supplies blood to the heart itself
coronary circulation
What is the blood supply to the lungs
the pulmonary circulation
what is the blood supply to the rest of the body
the systemic circulation
What happens in the pulmonary circulation
pulmonary arteries carry deoxygenated blood from the heart to the lungs to be oxygenated, which is carried back to the heart by the pulmonary veins
What happens in systemic circulation
Arteries carry oxygenated blood from the heart to the rest of the body to be used by the cells, and the deoxygenated blood is carried back to the heart by the veins.
What are the three main types of blood vessels
arteries (carry blood away from heart)
capillaries (exchange of water, nutrients and waste products between blood and tissues)
veins (carry blood back towards the heart)
What are the three structural layers of the arteries and veins
- Outer fibrous layer (tunica externa)
- Middle layer of muscle and elastic tissue (tunica media)
- Inner layer of smooth endothelium (tunica intima)
What is the function of the tunica externa
anchors blood vessels to nearby organs, nerves and other blood vessels and provides passage for nerves and small lymphatic and blood vessels
What is the function of the tunica media
Smooth muscle allows vasoconstriction and vasodilation altering blood flow and pressure. Elastic fibres allow for expansion and recoil, with collagen providing structural support
What is the function of the tunica interna
Enhances flow and prevent coagulation. Selectively permeable and can secrete vasoactive substance to alter diameter of blood vessels.
What changes structurally when arteries get smaller (further away from the heart)
The less elastic tissue is present to withstand less pressure of blood.
Muscle tissue increases allowing walls to dilate and constrict the size of BV.
Why is the tunica media of veins thinner than arteries
Because the venous circulation is under much lower pressure than the arterial side
Why do veins collapse if cut
Because the tunica media of veins is really thin
What do some veins have that prevents back flow of blood
Valves
What are capillaries made up of and what is the function of this
a single layer of endothelial cells which form a semipermeable membrane that separates blood and interstitial fluid
What is the net filtration pressure (NFP)
the difference in pressure at the two ends of the capillary
What does the conduction system consist of
SA node, AV node, AV bundle (bundle of his), right and left bundle branches, purkinje fibres
What is a single cycle of electrical activity moving across the heart and causing contraction known as
The cardiac cycle
What is the pacemaker of the heart
The Sinoatrial node
What is the flow of electrical activity through the heart
SA initiates an impulse that spreads across the atria, triggering atria to contract simultaneously.
Blood pumped into ventricles.
Nerve impulse reaches the AV node in the wall of the septum.
Short delay to allow atria to finish contracting and to allow ventricles to fill with blood.
nerve impulse carried from AV node to ventricles through AV bundle (bundle of his).
AV bundle divides into right and left bundle branches passing down septum and dividing into each ventricle.
Subdivide into purkinje fibres to cover more surface area.
PKF pass over surface of both ventricles and trigger contraction of cardiac muscle pumping blood to lungs and rest of body.
What is a cardiac cycle
one complete heartbeat during which the heart contracts and relaxes (systole and diastole)
What is cardiac output
the volume of blood pumped out of the heart per minute
how do you calculate cardiac output
stroke volume x heart rate
what is stroke volume
the blood pumped out of each ventricle per heartbeat
what is the heart rate
the number of heartbeats in one minute
what is blood pressure
the pressure exerted by the blood against the arterial walls by the pumping force of the heart
how do you calculate blood pressure
cardiac output x peripheral resistance
what control systems in the body regulate blood pressure
autonomic division of the nervous system
RAAS of endocrine system
