Tag: cardiac cycle

The cardiac cycle refers to a complete heartbeat from its generation to the beginning of the next beat. The frequency of the cardiac cycle or the heart rate is expressed as heart beats per minute. Normal adult human heart rate ranges from 60-100 bpm. So, the correct answer is option B.

The sino-atrial node (SAN) is a mass of nodal tissue found in the upper part of right auricle. It generates the nerve impulses which is responsible for starting the contraction of the heart. It controls the rhythm of the heart contraction. Hence, it is called as the natural pacemaker of the heart.

Chordae _ tending are numerous, strong inelastic thread like tendons  present in the ventricles of the  mammalian heart.

This sequential event in the heart which is cyclically repeated is called the cardiac cycle. Each cardiac cycle consists of systole and diastole of both the atria and ventricles. Each cardiac cycle represents one heartbeat. The normal heart rate is about 72 beats per minute. The heart rate is same as pulse rate because the pumping action of the heart causes an increase in blood pressure in arteries that leads to noticeable pulse. Hence pulse rate can be defined as the rate at which the blood is pumped.

All vertebrates possess a muscular chambered heart. Fishes have a 2-chambered heart with an atrium and a ventricle. In fishes, the blood transports nutrients when the heart pumps blood throughout the body. Animals like hydra and sponges do not possess any circulatory system. The water in which they live brings food and nutrients as it enters their body. The water carries waste materials and carbon dioxide as it moves out. Hence In animals like hydra and sponges, there is no blood for transport of nutrients.

• The amount of blood pumped by the heart per minute is called the cardiac output.
• The heart of a normal person beats 72 times per minute. This is called the heart rate. During each and every heartbeat, the ventricles pump about 70 ml of blood.
• This is known as stroke volume. This means heart pumps 72 x 70 ml = 5040 ml or approximately 5 liters of blood per minute.
  
  Thus the correct answer is option C.

The pulse rate is the number of times one can feel a pulse in one minute. The radial artery is present on the thumb side of the wrist. To measure the pulse rate place two fingers between the bone and the tendon over your radial artery. Count the number of beats in 15 seconds, multiply this with four you will get the pulse rate. Therefore The pulse rate can be determined from the arteries.

• This sequential event in the heart that is cyclically repeated is called the cardiac cycle. Each cardiac cycle consists of systole and diastole of both the atria and ventricles. 
• Each cardiac cycle represents one heartbeat. The number of heartbeats per minute in resting person is called a normal heart rate. 
• The normal heart rate is about 72 beats per minute. Hence the unit of measurement of the heartbeat is Beats per minute.