Circulatory system chapter class four science
0 likes214 views
There are three main types of muscles in the body - smooth, skeletal, and cardiac. Smooth muscles are involuntary and work internally for digestion and excretion. Skeletal muscles are voluntary and attached to bones via tendons, allowing for movement. Cardiac muscle is involuntary and makes up the heart, contracting and relaxing to pump blood. The circulatory system moves blood around the body via arteries, veins, and capillaries. Blood carries oxygen, nutrients, wastes, and defenses. The heart pumps blood through two circulations - to the lungs and throughout the body. Regular exercise and a healthy diet help maintain a healthy circulatory system.
Circulatory system chapter class four science
- 2. Observe your body; do all the bones move? No, some bones are movable and some are fixed. The bones of our skull are fixed. In our body, some muscles are attached to bones, as in our arms.
- 3. However, a few other muscles have no direct connection with bones, like the muscles of our heart. There are three different types of muscles. Let’s find out what they are and how they work.
- 5. Smooth muscles: These muscles have a very smooth, uniform appearance when observed under a microscope. Work: smooth muscles are involuntary as we cannot control their movement. These muscles perform actions without us thinking about them. They contract and relax to allow digestion and excretion.
- 6. Skeletal muscles: Skeletal muscles work with our bones to give us strength. Skeletal muscles are attached to bones by tendons. Tendons are thin, flexible strings made up of tough tissue. Work: skeletal muscles are voluntary in action as we can control their movements. Our leg won’t bend to kick the football unless we want it to.
- 7. Heart/Cardiac Muscle: The heart or cardiac muscle makes up the heart. Our heart is made up of cardiac muscle. The heart is an important component of the circulatory system. Let’s look at this body system in detail. Work: cardiac muscle contracts and relaxes to pump blood out of and into the heart. It is also involuntary as it works without our help.
- 8. Circulatory system: This vital body system is composed of the heart, blood, and vessels that carry blood. Let’s look at these parts one by one.
- 9. It is fluid that moves through blood vessels. Our blood consists of plasma, blood cells and platelets. Plasma is a liquid component of blood. It contains proteins, nutrients and wastes. Red blood cells carry oxygen and carbon dioxide. White blood cells fight against disease-causing microorganisms. They are helpful in improving our internal defense mechanism. Platelets help to clot blood when you get injured Blood:
- 11. Blood is of no use if it is not pumped throughout the body. This important function is performed by our heart. Heart-the muscular pump: The heart is an important organ in the circulatory system. It is a hollow, muscular pump that circulates blood throughout the body.
- 12. Structure of the heart: The human heart has four chambers. The upper two chambers are the right and left atriums. The lower two chambers are the right and left ventricles. The size of an adult’s heart is about a closed fist.
- 13. Parts of the Human Heart:
- 14. Dual circulatory system: Our heart performs two circulations: one from the heart to the lungs and the other from the heart to all other body parts.
- 15. Circulation of deoxygenated blood: 1.Deoxygenated blood from the body enters the heart through the right atrium. 2.It is then pumped into the right ventricle. There is a valve present between the right atrium and the right ventricle. It is known as tricuspid valve, as it has 3 flaps. The function of the heart’s valves is to control the flow of blood. 3.The right ventricle contracts and blood is pumped into the lungs to take oxygen.
- 16. Circulation of oxygenated blood: 1.After getting oxygenated, blood enters the left atrium. 2.The left atrium pumps this blood into the left ventricle. The valve present between the left atrium and left ventricle is called biscuspid or mitral valve, as it has 2 flaps. 3.The left ventricle pumps blood to the aorta and to the rest of the body.
- 17. Blood vessels: There are three different types of blood vessels: arteries, veins and capillaries.
- 18. Arteries: carry blood away from the heart. They are the thickest blood vessels with muscular walls. Oxygen-rich blood is pumped from the heart into the aorta. This huge artery then divides and blood is circulated throughout the body. The arteries branch out into arterioles, which are smaller and less elastic.
- 19. Veins: carry blood back to the heart. They contain valves that prevent blood from flowing backward. Veins are thinner and less flexible than arteries. The two largest veins are the superior vena cava and the inferior vena cava. The veins branch out into venules.
- 20. Capillaries: are a network of very thin blood vessels. They connect the arteries and veins and deliver nutrients and oxygenated blood to cells. They also remove waste products such as carbon dioxide from cells.
- 21. Keeping circulatory system health: A healthy body must have a good circulatory system. Some of the ways to help the circulatory system work well are given below. 1.Regular exercise makes our muscles strong and healthy. 2.Different physical activities such as running, swimming, playing football, etc. help our circulatory system to work well. 3.Healthy food is also a key component to keep our body healthy. Food containing less fats and sugar is good for us.