Lecture 4 - Cardiovascular system, Anatomy of the Heart (part I) Flashcards
Level of organisation in the cardiovascular system
Cardiovascular system is made up of organs that consist of the heart (pump), arteries-carries what the heart is pumping (supply), veins-drains blood towards the heart/lymphatics-some fluid leaves the blood vascular system and gets into the surrounding interstitial tissues and that fluid we bring back into the cardiovascular system via lymphatics(drainage) and capillaries (exchange). These organs are made up of vascular tissue which is made up of connective tissue and cells. The cells consist of epithelia and muscle (cardiac muscle which is only found in the heart and smooth muscle which is on the walls of blood vessels)
Arteries
blood vessels that carry blood AWAY from the heart
Veins
blood vessels that carry blood TOWARDS the heart
Blood vascular system
A closed supply and drainage system, it is a continuous loop.
Pump at centre forming a loop taking blood out to a target tissue and returning it in a closed loop back to the heart
Lymphatic (vascular) system
An open-entry drainage system, it is a one way system
Some fluid can leave and get to the surrounding tissue. We have a mechanism of these porous finger like projections sitting in the tissue that can act like drainage channels that can bring the fluid back into the blood vascular space/bringing fluid back that has left the blood vascular space back into the blood vascular space
What two system make up the cardiovascular system?
Blood vascular system and the lymphatic (vascular) system
Systemic circulation
Systemic circulation carries oxygenated blood from the left ventricle, through the arteries, to the capillaries in the tissues of the body. From the tissue capillaries, the deoxygenated blood returns through a system of veins to the right atrium of the heart.
Circuit that sends oxygen-rich blood to the tissues of the body and brings oxygen-poor blood back to the heart
Veins and arteries - the lungs
On the right side we have an artery carrying deoxygenated blood under high pressure and velocity and this pushes that blood into the lungs for reoxygenation and from the lungs we have a vein carrying oxygenated blood back to the heart which is then pushed out into another big loop called the systemic circulation.
Systemic vs pulmonary circulation
The cardiovascular system is composed of two circulatory paths: pulmonary circulation, the circuit through the lungs where blood is oxygenated, and systemic circulation, the circuit through the rest of the body to provide oxygenated blood.
Pulmonary circulation
The deoxygenated blood shoots down from the right atrium to the right ventricle. The heart then pumps it out of the right ventricle and into the pulmonary arteries to begin pulmonary circulation. The blood moves to the lungs, exchanges carbon dioxide for oxygen, and returns to the left atrium.
Supply side of the cardiovascular system
Arteries are the only supply path
Major arteries are situated to avoid damage because they are carrying blood at high pressure and at high velocity and if damaged the ability to lose high volumes of blood is high e.g. deep in the trunk (free from injury on anterior surface); on flexor aspect of limbs (anterior surface of upper limbs (in anatomical) for example)
Important structures often receive simply from two sources (two separate arteries) - this protects these structures. For example in the hand there is the radial artery and the ulna artery, the brain has 4 because you don’t want any damage to be able to compromise the role of the brain
Arteries change their name at each major branch
Exchange network of the cardiovascular system
Capillaries of vaarying degrees of permeability …the permeability can change depending on the tissues demands. Permeability means how easy it is to cross from the blood to the surrounding tissues
Continuous (controlled, tight) - tight control over what can enter the capillaries, epithelial lining is a continuous cellular barrier
Fenestrated (leaky) - not big enough for blood cells to leave but make it easier for things in solution to enter or leave the capillary
Sinusoidal (very leaky) - for example in the liver
Drainage system of the cardiovascular system
3 pathways for drainage (away from exchange surfaces) …
Deep veins - run back win opposite direction to deep supply arteries
Superficial veins - veins on the back of the hands for example
Lymphatics
Why is it better to get a cut to a superficial vein?
Draining blood at lower pressure and lower velocity so if cut then you only need to apply light pressure to stop it
CSA of veins and arteries
Cross-sectional area of veins is at least twice that of arteries (to shift the same volume of blood per second). Otherwise there would be a volume mismatch and swelling would occur. To compensate for the difference in physiology between supply and drainage channels we need to make sure that veins have a greater CSA to make sure that we shift the same volume back to the heart per second as we are pumping to the target tissue per second.
Heart shape
Blunt, cone shaped Pointed end is called the apex Broad end (top) is called the base - major pipes come off of this part
Approximate size of heart
Size of the heart is approximately that of a closed fist
Location of heart
The base is sitting between the space of the 2nd and 3rd ribs whilst the apex will be sitting in a line from the midclavicular line and we come down to the space between the 5th and 6th ribs and at this point it is approximately where the apex is
PMI
Point of maximum impulse - left midvlaviculaar line between the 5th and 6th rib
Called this because the apex as a result of the rotation and tilt is now pointing towards the anterior chest wall between the 5th and 6th ribs so when the heart beats it is banging away on the front of the chest at that space
This is the point where we put the stethoscope to get the loudest and largest heart sound
