The Cardiovascular System (Blood Vessels, the Heart And Heart Function)

Question 1

Identify the vessels that make up the circulatory system. Describe the structure and function.

Answer 1

The veins and arteries both contain three layers of tissue:
-tunica adventitia
-outer layer
-fibrous tissue
-protects and supports the vessel

-tunica media
-middle layer
-containing smooth muscle and elastic tissue

-tunica intima
-smooth lining layer- one cell thick

1. Arteries and arterioles:
   -arteries are the arterioles carry blood AWAY from the heart
   -arterioles branch into enormous network of capillaries (tiny exchange vessels which allow exchange of water, nutrients and oxygen into issue and cellular waste like carbon dioxide into the bloodstream to be transported away
   -has thick walls to withstand the high pressure in arterial system
   -larger arteries = more elastic tissue and little smooth muscle -> allows vessel wall to stretch to absorb the pressure wave generated when the heart beats
   -arterioles- the tunica media is entirely smooth muscle -> allows diameter to be controlled and regulates the pressure in them
2. Capillaries and sinusoids:
   -smallest arterioles branch into huge numbers of minute capillaries
   -has single layer of endothelial cells sitting on a very thin basement membrane, permeable to water and other small molecules
   -blood cells and large molecules such as plasma proteins are normally too large to diffuse
   -capillary diameter is about 3-4 micrometers is about 170 in liver (because rapid exchange of materials are important)
   -in certain places the capillaries are wider and leakier than normal, they are called sinusoids
3. Veins and venules:
   -always carry blood TO the heart
   -always carry deoxygenated blood, except for the pulmonary vein
   -carry blood under low or negative pressure
   -have thin walls- have less muscular tissue than arteries
   -have less connective tissue than arteries
   -have a wide lumen

Question 2

Describe how the pressure changes as blood progresses from the arteries through the venous system

Answer 2

-arterial walls are thicker than venous walls to withstand the pressure of blood in the arterial system. The structure of the arterial walls depends on how close the artery lies to the heart. The largest artery in the tunica media contains more elastic tissue and little smooth muscle. This allows the vessel wall to stretch because it is absorbing the pressure wave that is generated because of the heart as it is beating. The arteries become smaller to arterioles. Due to the tunica media consisting of smooth muscles, it enables the diameter to be precisely controlled which allows the pressure to be regulated.
-capillaries meet to for my tiny venules. The blood pressure drops in the capillary beds so that the blood passing through the venous system is under low pressure. This is why venous walls are thinner than arterial walls, however they have the same layer of tissue when cut the veins collapse whereas the arterial walls remains open. When artery is open, blood spurts out of a high pressure however the vein is slower

Question 3

Describe the role of the skeletal muscles and valves in the return of blood top the heart

Answer 3

-valves- prevent backflow of blood, help the return of blood to the heart, open when the blood flows towards the heart and close when blood might flow back due to gravity
-valve and skeletal muscle pump to ensure a one way flow back to the heart. Return of blood to the heart is facilitated by skeletal muscle. Deep lying veins are compressed by skeletal muscle forcing blood through the circulatory system back to the heart
-open when pressure is higher behind the valve and close when pressure is higher in front of valve, prevents backflow

Question 4

Define the pulse and identify the major points of palpating

Question 5

Describe the position of the heart, its shape and relationship to the lungs, major vessels, diaphragm and oesophagus

Answer 5

-the heart lies obliquely in the thoracic cavity (slanted in chest cavity) in the mediastinum (space between the lungs) slightly more to the left of the chest. The apex (tip) is about 9cm left of the midline at the level of the 5th intercostal space (space between the ribs). The heart is cone shaped
-the heart is laterally to the lungs. The left lung overlaps the left side of the heart
-the heart is superiorly to the major blood vessels for example the aorta, superior vena cava, pulmonary artery and pulmonary veins. This enters the heart as its base
-the heart is posteriorly to the oesophagus, trachea, left and right bronchus, descending aorta, inferior vena cava and thoracic vertebrae
-the heart is anteriorly to the sternum, ribs and intercostal muscle

Question 6

Identify the four chambers: the septum, apex and base, the four valves, the chordae tendinease and the four vessels entering and leaving the heart

Answer 6

1.right atrium receives the deoxygenated blood then empties it into the right ventricle. The right atrium then pumps blood into the pulmonary arteries which sends it to the lungs to pick up oxygen
2. Left atrium received the oxygenated blood from the lungs then empties it to the left ventricles, left ventricles pump oxygenated blood to aortic valve out of the rest of the body
3. The septum forms a barrier between two ventricles of the heart and allows blood to pass from the left to right side of the heart, the heart is divided into a right side and left side of the septum, a septum is a partition consisting of myocardium covered endocardium
4. Apex and base- apex is formed by the left ventricle, this is the base of the heart. The posterior part is formed by both atria

Four valves: valves open and shut to keep the blood flowing the correct way
1.tricuspid valve helps to keep blood flowing in the right direction through the heart, the tricuspid valve has three flaps of cusps
2. Mitral valve (bicuspid valve) keeps blood moving in the right direction
3. Pulmonary valve acts one way door from the heart to right ventricle, the opening of the pulmonary artery is guarded by the pulmonary valve, formed by three semilunar cusps, prevents back flow of blood into the right ventricle when ventricles relax
4. Aortic valve- controls the flow of blood from the heart to the rest of the body

-the chordae tendineae connects the atrioventricular valves (tricuspid and mitral) to the papillary muscles within the ventricles. The valves are prevented from opening upwards into the atria by in elastic tendinous cords chordae tendineae. This fastens the interior surface of the cusps to the papillary muscles. The papillary muscles are tiny extensions of the myocardium, anchor the chordae tendineae firmly to the ventricular wall

-there are five great vessels leaving the heart pulmonary artery, pulmonary vein, aorta, superior and inferior vena cava