6. CARDIOVASCULAR SYSTEM II Flashcards
Structure and function of the heart. Blood pressure, cholesterol and pulse. Signs, symptoms, investigation procedures and some orthodox treatments of common heart and blood vessel pathologies.
Describe the difference between ‘systemic circulation’ and ‘pulmonary circulation’
‘systemic circulation’ is the blood from the heart that is distributed around the body before returning to the heart and ‘pulmonary circulation’ is the blood going from the heart to the lungs and back to the heart.
Name the three layers present in blood vessels
Tunica externa - layer of elastic + collagen fibres
Tunica media - layer of smooth muscle
Tunica intima - single layer of endothelium
Where is the majority of blood found in the body?
Veins and venules (64%)
Explain the role of the portal vein
The portal vein collects blood from the spleen, pancreas and digestive system and takes it to the liver for filtering before it returns to the heart
Name the three layers of the heart wall and their main functions
Pericardium: Outer layer of of the heart that keeps it in position in the thorax and allows it to move freely without friction
Myocardium: The middle muscular layer that pumps the blood
Endocardium: The innermost layer that provides a smooth lining for the heart chambers and valves.
Name the predominant fuel used by cardiac muscle
Fatty acids (50-70%) [Glucose 30%]
Describe the role of the Sino-atrial node
It is the ‘pacemaker’ of the heart and initiates cardiac contraction
What is meant by ‘pulse rate’
A blood pressure wave originating from the heart
What is the average adult pulse rate
70-90 bpm
Define ‘cardiac output’
The volume of blood being pumped out by the heart per minute
Explain the following terms:
a. Tachycardia
b. Bradycardia
c. Systole
d. Diastole
a. Tachycardia: Resting heart rate over 100bpm
b. Bradycardia: Resting heart rate under 60bpm
c. Systole: The force that drives blood out of the heart (contraction)
d. Diastole: Period of relaxation when the heart fills with blood.
Name two functions of cholesterol
- Plays an integral role in cell membranes (especially in the brain)
- Vital component of sex hormones (i.e. oestrogen & testosterone)
- Plays an important role in Vitamin D and Calcium metabolism
How is cholesterol transported around the body?
Since cholesterol is hydrophobic, it is transported around the body as lipoproteins (bound to proteins)
Explain the function of:
a. Low density lipoproteins (LDLs)
b. High density lipoproteins (HDLs)
a. Carries 75% of cholesterol in the blood from the liver to the cells of the body (when in excess it can deposit it in the arteries)
b. Removes excess cholesterol from cells and blood and transports it back to the liver (prevents accumulation of cholesterol in the blood)
Define atherosclerosis
A type of arteriosclerosis, it is the thickening and loss of elasticity of arterial walls
Outline the pathophysiology of atherosclerosis
- Damage of vascular endothelium: inflammation
- LDLs deposit on tunica intima, oxidises and attracts phagocytes
- Macrophages surround fatty material and create foam cells in trying to destroy it.
- Proliferation of smooth muscle cells
- Cap is formed to wall it off from the blood =arterial narrowing
Name the heart layer that contains cardiac muscle.
Myocardium
Explain what is meant by ‘auto-rhytmic’
The heart generates its own rhythm of contraction
List the four chambers of the heart
Right atrium
Right ventricle
Left atrium
Left ventricle
Is the right or left ventricle thicker?
Left
Give a detailed description of the flow of blood in the heart from entering via the right atrium to exiting via the aorta. Include all key structures and indicate if blood is oxygenated or deoxygenated.
Deoxygenated blood enters the right atrium via the superior and inferior vena cava. From here the blood is pumped into the right ventricle through the tricuspid valve. From the right ventricle the blood is pumped to the lungs through the pulmonary valve into the pulmonary trunk that branches into left and right pulmonary arteries. In the lungs the blood is oxygenated and flows to the left atrium via the pulmonary vein. The oxygenated blood then flows through the bicuspid / mitral valve into the left ventricle from where it is pumped through the aortic valve into the ascending aorta to the rest of the body as well as th coronary arteries that carry blood to the heart wall.
Describe the role of ‘ductus arteriosum’?
During foetal life (eight weeks+), a temporary blood vessel called the ductus arteriosum shunts blood from the pulmonary trunk to the aorta.
Explain how the following affects heart rate and contraction as well as blood vessels:
a) Sympathetic nervous system
b) Parasympathetic nervous system
a) Increases rate and strength
of contraction; causes vasoconstriction
b) Decreases rate and strength of contraction (via vagus nerve); little influence on blood vessels
List FOUR factors that influence heart rate and strength
Hormones, age, sex, body position, exercise, stress and temperature all influence heart rate and strength
Describe the role of the Sino-atrial node
The SA node is the ‘pacemaker of the heart’ - sets rate and rhythm - and it initiates cardiac conduction
Indicate where the Sino-atrial node is located in the heart
It is located in the right atrial wall
Describe in specific detail the conduction system in the heart, commencing with the Sino-atrial node (include all key structures and their functions)
- Sinoatrial node (SA node):
The SA node sets rate and rhythm of the heart.
From the right atrial wall, it initiates cardiac conduction.
Each action potential from the SA node propagates through each atrium via gap junctions, causing atrial contraction. - Atrioventricular node (AV node):
A relay station which conducts impulses at a slightly slower rate to allow the atria to finish contracting.
Located in the bottom right of the interatrial septum. - Atrioventricular bundle (‘bundle of His’):
Located just below AV node, it is the only site where action potential can conduct from atria to ventricles. - Right and left bundle branches:
From the bundle of His, the action potential enters the left and right bundle branches, which extend the interventricular septum towards the apex of the heart. - Purkinje fibres:
Finally the Purkinje fibres rapidly conduct the action potential beginning at the apex of the heart, up the remainder of the ventricular myocardium causing ventricular contraction.
Which type of respiration does cardiac muscle require?
Aerobic
Name the predominant fuel used by cardiac muscle?
Fatty acids (50-70%)
Name the product that the heart can use to produce ATP during exercise.
Lactic acid
Explain what is meant by ‘pulse rate’
The pulse is a blood pressure wave originating from the heart. The rate varies depending on the stage of life
What is the average adult pulse rate?
70 to 90 bpm
Describe the difference between a ‘P wave’ and ‘T wave’ detected by an ECG.
The P wave represents atrial depolarisation (from SA node) while the T wave is ventricular repolarisation (resting).
Define cardiac output
Cardiac output is the volume of blood being pumped out by the heart per minute
Explain the following terms:
a. Tachycardia
b. Bradycardia
c. Systole
d. Diastole
a. Resting heart rate over 100 bpm.
b. Resting heart rate under 60 bpm.
c. The force that drives blood out of the heart (contraction).
d. Period of relaxation when the heart fills with blood.