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The 6 main functions of the CV are:
- Transport of nutrients (oxygen, glucose, fatty acids)
- Removal of waste from metabolic processes (CO2, urea, creatine)
- Transport hormones from the endocrine system to target organs
- Regulates temperature
- Involved in reproduction (eg feeding the foetus and erections)
- Facilitates defence by transporting immune cells.
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The CV system composes which 3 elements
- The heart
- Blood vessels
- Blood
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The 4 divisions of the CV system are
1. Systemic (passage of blood round the body)
2. Pulmonary (passage of blood to the lungs)
3. Coronary (supply of blood to the heart itself)
4. Hepatic (supply of blood to/from the liver)
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Describe the exact location/position of the heart
In the mediastinum, behind the sternum and in front of the spine; between the lungs and above the diaphragm. The heart sits upside down (apex at the bottom), at an angle of 60 degrees. The base is behind the sternum; the apex is 9cm left of the midline
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The heart lays at what degree from the vertical?
60 degrees
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The average size of the heart is (in cm)
10cm long, 9cm wide, 6cm deep
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Name and describe the outer layer of the heart
Pericardium. This is a thick outer coating, with 2 serous layers; fluid fills the pericardial space between the 2 layers, which prevents friction when the heart beats
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Name and describe the middle layer of the heart
Myocardium. This is the heart muscle, and is therefore a very thick layer
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Name and describe the innermost layer of the heart
Endocardium. Lines the chambers, covers the inside of the heart, and is lined with endothelial cells
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The ability to generate an electrical impulse is called
Autorhythmicity
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Describe the atria
The topmost two chambers of the heart (left and right). There is little muscle here, and they are separated by an intra-atrial septum
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Describe the ventricles
The two lowermost chambers of the heart (left and right). They have thick muscle in the myocardium, and are separated by a ventricular septum
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Name the 4 valves within the heart
- Bicuspid (left atrium)
- Tricuspid (right atrium)
- Pulmonary (from right ventricle to lung)
- Aortic (from left ventricle to aorta)
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The tendons that prevent cusp inversion are called
Chordae Tendinae
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The muscles to which these tendons are attached are called
Papillary muscles
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Starting at the vena cava describe fully the blood flow through the heart
The vena cava brings deoxygenated blood back to the heart. It enters the heart at the right atrium. During atrial systole the blood flows through the tricuspid valve into the right ventricle.
During ventricular systole the blood flows through the pulmonary valve into the pulmonary artery and into the lungs.
Oxygetated blood from the lungs flows back to the heart via the pulmonary veins, into the left atrium. During atrial systole the blood flows through the bicuspid valve into the left ventricle.
During ventricular systole the blood flows through the aortic valve and into the body
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List the main coronary arteries
Right and left (is this correct?)
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Describe the flow of electrical current from the SA node
The SA (Sino-Atrial) node is the pacemarker of the heart. It sends impulses across both atria, so both contract at once. The SA determines how often the heart should beat, with regular impulses.
Electrical instability allows the charges to de-poloarise @ 60-80BPM
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Describe the cardiac cycle
The cardiac cycle consists of article systole (0.1 seconds) when both atria contract; this is followed by ventricular systole (0.3 seconds) when both ventricles contract. Finally diastole is when the entire heart relaxes (0.4 seconds).
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BP is defined as
Pressure exerted by the blood onto arterial walls
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Cardiac output is described as
The amount of blood expelled from the ventricles in 1 minute. It is measured by multiplying the stroke volume (c70ml) by the heart rate (c75) = 5.25litres
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The cardiovascular centre is located in
Medulla oblongata
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Baroreceptors measure what?
Blood pressure.
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The pulse at the antecubital fossa is called
Brachial
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Bradycardia refers to a HR below:
60
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Tachycardia refers to a HR above
100
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The normal heart rate is between
60-100
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List the 5 types of blood vessel
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
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Which blood vessels have valves
Veins (to prevent backflow of blood)
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Venous return is reliant on
- Position of the body
- Muscular contractions
- Respiratory movements
- Suction of the heart
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Blood transports what?
- Oxygen
- Nutrients
- Hormones
- Heat
- Protective substances
- Clotting factors
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Name the blood cells (name and colour)
Erythrocytes (red).
Leucocytes (white)
Thrombocytes (platelets)
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The average blood volume of adults is (mls/kg)
70ml / kg
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The average blood volume of children is (mls/kg)
80ml / kg
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Erythrocytes are what shape and why?
Concave. No nucleus, so they have a greater surface area for O2 uptake.
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What DNA is in erythrocytes?
Mitochondrial DNA
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What molecules in DNA pick up O2?
Iron
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Where are leucocytes and erythrocytes formed?
Leucocytes - red bone marrow, spleen, liver.
Erythrocytes - bone marrow.
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What do leucocytes do?
Fight infection
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What do thrombocytes do?
Clot blood.
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Blood plasma is 92% what?
Water.
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What factors affect heart rate?
- Gender
- ANS
- Exercise
- Hormones
- Temperature
- Emotion
- Baroreceptor reflex
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Where are your radial, brachial, carotid, femoral and dorsal pedal pulses?
- Radial - wrist.
- Brachial - elbow.
- Carotid - neck.
- Femoral - groin.
- Dorsal pedis - foot.
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What do chemoreceptors measure?
Breathing rate and heart rate.
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Which nerve controls the SA node and the AV node?
Vagus nerve
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Does sympathetic or parasympathetic nervous control regulate heart rate?
They both do!
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What does the AV node do?
Transmits impulses from atria to ventricles (with a small delay after the SA node to allow the atria to finish contracting). The AV node allows impulses through one at a time.
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Where does electrical flow go to after the AV node?
To the AV bundle, and into the Perkinje fibres.
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The "LUB" and "DUB" sounds of the heart beat are made by what?
LUB - mitral and tricuspid vales shutting.
DUB - pulmonary and aortic valves shutting.
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How ofte does the heart beat?
75 bpm.
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