The study of plant anatomy and physiology is an integral part of Biology Topics.
Is pulse and heart beat the same?
The heart pumps blood into arteries by contracting. When the heart contracts, it becomes smaller in size and pushes the blood into main artery with a great force. Then the heart relaxes (comes back to its original size) and gets filled up with blood from pulmonary vein. In this way, the heart keeps on contracting and relaxing again and again to pump blood into the body continuously.
One complete contraction and relaxation of the heart is called a heartbeat. The heart of an adult person usually beats about 72 to 80 times in a minute (while resting). This means that the heart pumps out blood to the arteries about 72 to 80 times per minute. Thus, the average heartbeat of an adult person while resting is 72 to 80 per minute. This is called the heart rate. We can feel our heartbeats if we place our hand on the left side of our chest just above the heart region. The heart beats can be counted easily by counting the pulse.
Though the average number of heartbeats of an adult person while resting is about 72 to 80 beats per minute but the number of heartbeats increase too much during and after a physical exercise or when a person is excited. For example, if we count our heartbeats after running for a while, we will find it to be more than 100 per minute. During rigorous exercise it can be as high as 150 to 200 beats per minute.
The heart beats Taster during and after an exercise because our body needs more energy under these conditions. The faster beating of heart pumps blood more rapidly to the body organs which supplies more oxygen to the body cells for rapid respiration to produce more energy. The increase in number of heartbeats caused by exercise, excitement, fear or nervousness, however, lasts for a short time after which it becomes normal. The heart rate in infants (small babies) is far higher than in adults.
A doctor listens to our heartbeats with the help of an instrument called stethoscope (see Figure). The stethoscope amplifies (makes louder) the sound of heartbeats so that the doctor can hear the heartbeats clearly.
A stethoscope consists of three parts:
- a chest piece (which carries a sensitive diaphragm at its bottom). The diaphragm amplifies the sounds of heartbeats.
- two ear pieces (which are made of two metal tubes). These are put by the doctor into his ears.
- a rubber tube which joins the chest piece to the ear pieces. The rubber tube transmits the sound from the chest piece into the ear pieces.
A stethoscope is used to hear clearly the heartbeats’ by placing the chest piece over the heart region of chest. The diaphragm amplifies the sounds of heartbeats coming from within the body and the rubber tube and ear pieces transmit these sounds to the ears of the doctor. Doctors can get clues about the condition of our heart by listening to the heartbeats through the stethoscope.
We can make a model of stethoscope by using the materials available around us as follows : Take a glass funnel of about 6 to 7 centimetre diameter. Fix a 50 centimetre long rubber tube tightly on the stem (narrow end) of the funnel [see Figure (a)]. Stretch a thin rubber sheet (or a balloon) and fix this stretched rubber sheet on the mouth of the funnel tightly with the help of a rubber band and adhesive tape, etc. Our stethoscope is ready for use [see Figure (a)], We can hear our heartbeats by using this model of stethoscope as follows : Put the open end of rubber tube in one of your ears and
Every time the heart beats, blood is forced into arteries. This blood makes the arteries expand a little. The expansion of an artery each time the blood is forced into it, is called pulse. Each heartbeat generates one pulse in the arteries, so the pulse rate of a person is equal to the number of heartbeats per minute. Since the heart beats about 72 to 80 times per minute, therefore, the pulse rate of an adult person while resting is 72 to 80 per minute. Thus, the pulse rate is the same as the heart rate. Just like heartbeats, the pulse rate of a person is higher after a physical exercise or when a person is excited.
Most of our arteries lie deep inside our body and hence cannot be used to feel the pulse. But at some places in our body like the wrist, temple and neck, the arteries are close to the surface of skin and pass over bones. So, we can feel the pulse at wrist, temple and neck by pressing the artery lightly with our finger tips. The pulse is traditionally taken above the wrist.
We can feel our own pulse and find the pulse rate as follows: The pulse can be felt with fingers placed gently on arteries at the wrist. We place the first two fingers (Index finger and middle finger) of our right hand on the inner side of our left wrist and press it gently (see Figure). We will feel some waves touching our fingers. These waves are the pulse. We can count the number of such waves (or thumpings) in one minute by using a watch. This will give us the pulse rate (per minute).
We usually see the doctor taking the pulse rate of a patient by keeping his fingers on the wrist of the patient and at the same time looking into his watch. Doctors can tell by counting the pulse rate and listening to heartbeats whether a person is well or not. This is because the pulse rate and heartbeats change according to the condition of our heart.
The Case of Sponges and Hydra
Sponges and Hydra are simple animals which live in water (see Figures). Sponges live mostly
in sea water whereas Hydra lives in freshwater. Sponges and Hydra do not have blood, blood vessels or heart. In other words, the animals such as sponges and Hydra do not possess any ‘circulatory system’. In sponges and Hydra, the water (in which they live) brings food and oxygen as it enters their bodies.
The water also carries away carbon dioxide and other waste materials as it moves out of their bodies. Thus, the simple animals such as sponges and Hydra do not need a circulatory liquid like the blood. It is the water in which sponges and Hydra live which helps in moving various materials in their bodies. Amoeba and Paramecium are also tiny animals which live in water and do not have blood in them.