Histamine in the blood is secreted by:
1. | Mast cells | 2. | Macrophages |
3. | Eosinophils | 4. | Basophils |
A person with AB blood group:
1. Has A and B antigens in his plasma
2. Lacks any antibodies on RBC surface
3. Can receive blood transfusion from a person of his own group.
4. Can donate blood to all other group recipients
The inter-atrial septum in the human heart can be best described as:
1. A thin muscular wall
2. A thick muscular wall
3. A thin fibrous tissue
4. A thick fibrous tissue
The sino-atrial node is the normal pacemaker of the human heart because:
1. | It is located in the right atrium. |
2. | It is the only part of the conducting system that can generate impulse. |
3. | It can generate the maximum number of action potentials in the conducting system. |
4. | It produces action potentials that are more in size than the other parts of the conducting system. |
What percentage of ventricular filling is achieved by atrial contraction?
1. 30
2. 50
3. 70
4. 90
The second heart sound during the cardiac cycle is produced by the:
1. Simultaneous opening of the atrioventricular valves
2. Simultaneous closure of the atrioventricular valves
3. Simultaneous opening of the semilunar valves
4. Simultaneous closure of the semilunar valves
In a surface ECG the QRS complex represents:
1. Atrial depolarization
2. Atrial repolarization
3. Ventricular depolarization
4. Ventricular repolarization
Normal activities of the human heart are regulated:
1. Intrinsically
2. By the autonomic nervous system
3. By the brain stem
4. By the diencephalon
A common symptom produced by myocardial ischemia is:
1. Hypertension
2. Vertigo
3. Angina
4. Hyperventilation
An increase in the blood flow to the atria of the heart can cause the release of:
1. Erythropoeitin
2. Atrial natriuretic factor
3. Renin
4. Aldosterone