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  4. Communicate about forces that cause the blood to circulate in humans: (i) pumping of the heart. (ii) contraction of skeletal muscles

Mechanism of Heartbeat

10.3 Mechanism of Heartbeat
 
Introduction
  • The heart is made up of cardiac muscles that intersect and are connected with one another.
  • This arrangement allows electric impulses to spread rapidly through the heart and at the same time, stimulates the cardiac muscle cells to contract simultaneously and uniformly.
  • Cardiac muscles are myogenic.
  • This means that the heart contracts and relaxes without receiving any impulse signal from the nervous system.
  • If the cardiac muscles are stored in a warm oxygenated solution that contains nutrients, these muscles will contract and relax rhythmically on their own.
 
A detailed diagram of the human heart showing its internal structures and labeled parts. The labels include the sinoatrial node, right atrium, atrioventricular node, right ventricle, Purkinje fibers, left ventricle, bundle of His, and left atrium. The diagram highlights the flow of blood and the electrical conduction system of the heart.
 
Blood Circulation in Human
  • The produced force that enables blood to circulate in humans is generated by the pumping of the heart and the contraction of the skeletal muscles.
  • The contraction of the heart is initiated and coordinated by the pacemaker.
  • The pacemaker is a group of specific heart muscle cells that initiates the rate of heart contraction and is located at the right atrium wall.
  • The pacemaker generates electrical impulses that spread rapidly through both walls of the atrium and causes the atrium to contract rhythmically.
  • The main pacemaker is called sinoatrial node (SA).
  • During heart pumping, the lub-dub sound can be heard.
  • The first ‘lub’ sound is produced when the tricuspid valve and the bicuspid valve close.
  • The second ‘dub’ sound is produced when the semilunar valves close.
  • The pumping of the heart helps in the distribution and flow of blood through the arteries, arterioles and blood capillaries.
  • However, the force produced by the pumping of the heart is insufficient for the blood flow to continue through the veins and return to the heart.
  • Besides, the blood is forced to flow against the force of gravity.
  • The presence valve in the veins ensures that the blood flows in one direction to the heart.
  • The blood flow in the veins is assisted by contraction of the smooth muscles found in the venule and vein walls and contraction of skeletal muscles around the veins.
  • The contraction of skeletal muscles presses and constricts the veins, causing the valve to open and allow blood to flow towards the heart.
 
 
 
The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of pandai.

Mechanism of Heartbeat

10.3 Mechanism of Heartbeat
 
Introduction
  • The heart is made up of cardiac muscles that intersect and are connected with one another.
  • This arrangement allows electric impulses to spread rapidly through the heart and at the same time, stimulates the cardiac muscle cells to contract simultaneously and uniformly.
  • Cardiac muscles are myogenic.
  • This means that the heart contracts and relaxes without receiving any impulse signal from the nervous system.
  • If the cardiac muscles are stored in a warm oxygenated solution that contains nutrients, these muscles will contract and relax rhythmically on their own.
 
A detailed diagram of the human heart showing its internal structures and labeled parts. The labels include the sinoatrial node, right atrium, atrioventricular node, right ventricle, Purkinje fibers, left ventricle, bundle of His, and left atrium. The diagram highlights the flow of blood and the electrical conduction system of the heart.
 
Blood Circulation in Human
  • The produced force that enables blood to circulate in humans is generated by the pumping of the heart and the contraction of the skeletal muscles.
  • The contraction of the heart is initiated and coordinated by the pacemaker.
  • The pacemaker is a group of specific heart muscle cells that initiates the rate of heart contraction and is located at the right atrium wall.
  • The pacemaker generates electrical impulses that spread rapidly through both walls of the atrium and causes the atrium to contract rhythmically.
  • The main pacemaker is called sinoatrial node (SA).
  • During heart pumping, the lub-dub sound can be heard.
  • The first ‘lub’ sound is produced when the tricuspid valve and the bicuspid valve close.
  • The second ‘dub’ sound is produced when the semilunar valves close.
  • The pumping of the heart helps in the distribution and flow of blood through the arteries, arterioles and blood capillaries.
  • However, the force produced by the pumping of the heart is insufficient for the blood flow to continue through the veins and return to the heart.
  • Besides, the blood is forced to flow against the force of gravity.
  • The presence valve in the veins ensures that the blood flows in one direction to the heart.
  • The blood flow in the veins is assisted by contraction of the smooth muscles found in the venule and vein walls and contraction of skeletal muscles around the veins.
  • The contraction of skeletal muscles presses and constricts the veins, causing the valve to open and allow blood to flow towards the heart.
 
 
 
The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of pandai.
Chapter : Transportation in Humans and Animals
Topic : Communicate about forces that cause the blood to circulate in humans: (i) pumping of the heart. (ii) contraction of skeletal muscles
Form 4 Biology
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