Concept about Tachycardia-The course is designed for the basic understanding of anatomical structures and physiological functions of human body, musculoskeletal system, digestive system, respiratory system; cardiovascular system; urinary system, endocrine system, reproductive system, nervous system, hematologic system, sensory organs, integumentary system, and immune system.The aim of the course is to acquire knowledge and skills regarding anatomy and physiology.
Concept about Tachycardia
Tachycardia:
When the heart rate is above the normal physiological limit. Usually above 100 beats/mins
Causes of tachycardia are :-
- Emotion.
- Exercise.
- Fever. Sympathetic system.
- Atrial flutter
- Atrial fibrillation.
- Most painful stimuli
- Hypoxia
- Hyperthyroidism
- Bainbridge reflex
Mechanism of increased heart rate in moderate exercise:
In moderate exercise
↓
Sympathetic stimulation
plus
Adrenaline release
↓
↑ed Heart rate
The heart rate increased in exercise due to –
- Sympathetic stimulation
- Adrenaline secretion.
- Reduction of vagal tone
- Rising of body temperature.
- Lactic acidosis.
Mechanism:
Sympathetic stimulation plus adrenaline release→ act on the cardiac muscle→ increase heart rate.
Heart sound
Heart sound:
When the heart valves close, the vanes of the valves and the surrounding fluids vibrate due to sudden pressure change which produces off sound that travel all direction through the chest wall and is audible with a stethoscope, this is heart-sound. The heart-sounds are usually described as “lub,dub,lub,dub”
Causes of different heart sound:
| Heart sound | Cause of heart sound |
| 1. First heart-sound (Lub) | Sudden closure of the mitral and tricuspid valves at the start of ventricular systole. |
| 2. Second heart-sound (Dub) | Sudden closure of the aortic and pulmonary valves just after the end of ventricular systole |
| 3. Third heart-sound | Inrushes of blood during rapid ventricular first filling period. |
| 4. Fourth heart-sound | Last rapid filling phase which is due to atrial contraction. |
Location of heart sound:
| Arca | Location |
| Mitral area | Left 5th intercostal space just medial to mid clavicular line |
| Tricuspid area | Left 4th intercostal space just lateral to the sternum. |
| Aortic area | Right 2nd intercostal space just lateral to sternum. |
| Pulmonary area | Left 2nd intercostal space just lateral to sternum |
Peripheral resistance:
The resistance that offered by the vascular tree which lies peripheral to the heart is called peripheral resistance. Or. It is the resistance against which the heart pumps.
Read more: