Term
| What type of muscle is cardiac muscle and how does this affect it's appearance? |
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Definition
| A specialised form of striated muscle which makes it appear 'stripey' in appearance which reflects the sarcomeric organisation. |
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Term
| What are the functions of the heart? |
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Definition
1. supply oxygenated blood containing nutrients (e.g. glucose) to the major organs.
2. remove waste products formed during metabolism (e.g. via the lungs). |
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Term
| Where is the heart located? |
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Definition
behind the sternum, situated at an angle.
behind the ribcage and extends from the 2nd rib to the 5th rib. |
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Term
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Definition
12-14cm long (size of an adult male's clenched fist)
weighs about 250-350g |
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Term
| How is the CV system divided? |
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Definition
3 parallel circuits:
1. Pulmonary circuit
2. Coronary circuit
3. Systemic circuit |
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Term
| What constitutes the pulmonary circulation? |
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Definition
1. deoxygenated blood is pumped by the RV to the lungs via the pulmonary artery
2. Gas exchange occurs in the lungs; CO2 is expelled and O2 is taken up by the blood.
3. Re-oxygenated blood returns to the LA of the heart via the pulmonary vein |
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Term
| What makes the pulmonary artery and veins different to the others in the body? |
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Definition
| The pulmonary artery is the only artery in the body to carry deoxygenated blood and likewise for the vein. |
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Term
| How is oxygenated blood supplied to the heart? |
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Definition
| via the left and right coronary arteries, of which the left is slightly larger. These arteries branch directly from the base of the aorta, just above the semilunar valve. |
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Term
| What does the right coronary artery split into? |
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Definition
the marginal artery (which serves the right ventricular wall)
and then continues round the posterior aspect of the heart |
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Term
| What does the left coronary artery split into? |
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Definition
| It emerges behind the pulmonary trunk and splits into the anterior interventricular artery (supplied the elft ventricular wall) and the circumflex artery (which anastomoses with the right coronary artery). |
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Term
| How is venous blood drained from the heart? |
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Definition
| into the coronary sinus, which in turn drains into the RA. From there the blood will go to the lungs for re-oxygenation via the pulmonary circuit. |
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Term
| Describe the systemic circulation |
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Definition
| LV pumps blood into the aorta which branches into smaller arteries. |
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Term
| How are the head and neck supported? |
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Definition
- the aortic arch which splits into the vertebral and right common carotid artery
- the left common carotid artery |
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Term
| How are the upper chest and arms supported? |
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Definition
- the right subclavian artery (from brachiocephalic trunk)
- the left subclavian artery (from aortic arch) |
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Term
| What do the subclavian arteries become? |
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Definition
axillary arteries which split into the brachial artery at the elbow.
the brachial artery splits into the radial and ulnar arteries. |
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Term
| How is the digestive tract supported? |
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Definition
stomach via the gastric artery
S&L intestines via the superior and inferior mesenteric arteries |
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Term
| How are the pelvis and legs supported? |
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Definition
the descending aorta splits into the common iliac arteries just superior to the pelvis
the common iliac artery splits into the internal and external arteries and supplies the pelvis and legs respectively
the legs are also supplied by the femoral arteries which are from the common iliac arteries. |
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Term
| Describe blood flow through the heart |
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Definition
1. blood returns from the body via the superior and inferior vena cavae
2. right atrium
3. right ventricle
4. pulmonary arteries
5. left and right lungs
6. pulmonary veins
7. left atrium
8. left ventricle
9. blood the flows through coronary and systemic circulations via the aorta. |
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Term
| What is the heart enclosed in? |
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Definition
| a double walled sac called the pericardium which is both fibrous and indistensible |
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Term
| Describe the outer layer of the pericardium |
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Definition
Fibrous pericardium
protects the heart and anchors it to adjacent structures like the diaphragm and the great vessels to stop it moving in the cavity, and to also stop it overfilling with blood |
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Term
| Describe the inner layer of the pericardium |
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Definition
Serous pericardium
extends to cover the epicardial surface of the muscular wall of the heart |
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Term
| Describe the pericardial cavity |
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Definition
| filled with a fluid to lubricate the membranes so they can glide over each other during the twisting of the heart when it contracts |
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Term
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Definition
| inflammation of the pericardial membrane - causes sharp chest pain left of centre - exacerbated by deep breathing and coughing |
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Term
| How is pericarditis diagnosed? |
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Definition
| using a stethoscope as you can hear the two membranes rubbing against each other |
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Term
| What is cardiac tamponade? |
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Definition
severe pericarditis that limits the extent of ventricle filling.
life threatening if the fluid is not drained quickly. |
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Term
| Where are valves located? |
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Definition
| between the atria, ventricles and great vessels on each side of the heart |
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Term
| Describe the Right AV valve |
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Definition
| 3 cusps and is called the tricuspid valve |
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Term
| Describe the left AV valve |
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Definition
| two cusps and is called the bicuspid or mitral valve |
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Term
| Describe the valves located at the entrance of ventricular outflow tracts |
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Definition
3 cusps (semilunar valves)
very delicate
guard the pulmonary artery and aorta entrances |
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Term
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Definition
1. when pressure is greater behind the valve, it opens
2. when pressure is greater in front of the valve, it closes and do not open in the opposite direction, they are one way. |
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Term
| What is the role of the papillary muscles? |
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Definition
| When the ventricles contract, pressure is higher in the ventricle than the atrium so the valve is forced shut. The papillary muscle contract and pull on the chordae tendinae to prevent the flaps from everting into the atrium. |
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Term
| How do ventricle muscle cells differ to skeletal muscle cells? |
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Definition
| They are much smaller (120micrometers long and approx 30micrometers wide). |
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Term
| What are cardiac muscle cells rich in and why? |
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Definition
Glycogen and myoglobin and contain a large number of mitochondria (about 30% of ventricular muscle cell volume is occupied by mitochondria).
This reflects the high energy demand of the tissue. |
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Term
| How are adjacent ventricular muscle cells joined together? |
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Definition
individual cells are bound together to form layers of heart muscle.
attachments are made via intercalated discs which creates the lattice. |
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Term
| What are the roles of intercalated discs? |
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Definition
1. firmly bind adjacent cells together; mechanical coupling.
2. they allow electrical coupling between adjacent cells. |
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Term
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Definition
| structures specialised for cell-to-cell adhesion |
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Term
| Describe the nexus/gap junction |
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Definition
| area of close contact membranes, where regular arrays of proteins called connexins are found. These forms large channels which allow passage of ions and other small molecules between one cell and another. |
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Term
| Define functional syncytium |
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Definition
| the result of electrical coupling means the heart behaves electrically as a single cell. |
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Term
| List the 5 other cell types within the heart |
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Definition
1. fibroblasts
2. endothelial cells
3. smooth muscle cells
4. conduction cells
5. cardiomyocytes |
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Term
| What is the function of fibroblasts? |
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Definition
| contribute to the ECM providing mechanical support |
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Term
| What is the function of endothelial cells? |
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Definition
| contribute to the lining of blood vessels |
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Term
| What is the function of SMC? |
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Definition
| in coronary veins and arteries |
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Term
| What is the function of conduction cells? |
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Definition
| generation and passing of electrical impulses |
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Term
| What is the function of cardiomyocytes? |
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Definition
| form the contractile apparatus of the atria and ventricles |
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Term
| What principle do cardiac cells obey? |
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Definition
the all or nothing principle
if you electrically excite a part of it you electrically excite all of it |
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