Quite simply, muscles move you. Muscles are bundles of cells and fibers that work in a simple way: they tighten up and relax. The nervous system is the control center of the human body. It is made up of the brain, spinal cord, and nerves. It receives and interprets stimuli and transmits impulses to organs. Your brain uses the information it receives to coordinate all of your actions and reactions.
The human reproductive system ensures that humans are able to reproduce and survive as a species. It is made up of organs such as the uterus, penis, ovaries, and testes. The primary function of the respiratory system is to supply the blood with oxygen in order for the blood to deliver oxygen to all parts of the body.
The respiratory system does this through breathing. It consists of the nose, larynx, trachea, diaphragm, bronchi, and lungs. The skeletal system provides the shape and form for our bodies in addition to supporting and protecting our bodies, allowing bodily movement, producing blood cells, and storing minerals.
Muscles allow us to move because they are able to contract become shorter and relax become longer. A video on muscle contraction and relaxation in the arm. The muscle that moves the fastest in your body is the muscle that controls your eyelids! There is a reason why we use the phrase "in the blink of an eye" to mean very fast! Bones provide support and help to form the shape of the body. The place where bones meet is called a joint - think of your knee or elbow joint, or your finger and toe joints. Babies are born with bones while adults only have bones. As babies grow into adults, many smaller bones fuse together to form bigger bones.
Cartilage is stiff yet flexible and is found between bones in joints and between the ribs and breastbone as indicated in the diagram. It also forms the ears, nose and bronchial tubes, and forms discs between the bones of the spinal column. Your muscles attach to the bone with strong cords called tendons. You can feel some of the tendons in your body, for example behind your ankle called the Achilles tendon. Ligaments occur between bones at joints and hold bones together within the joint. Ligaments are extremely strong. We can move our entire bodies from one place to another through self-propulsion.
This is called locomotion. Locomotion is different to movement. Movement is the change in shape, direction, position or size of a part of the body. Animals show movement and locomotion. What about plants? Do you think plants show movement and locomotion? Ask your learners this question to get their answers. The answer is that plants only have movement as they are able to change shape and grow, and even change direction in response to a light or water source, but they are rooted to one place - they cannot locomote move from place to place.
Encourage learners to take notes on this discussion either in a separate notebook or in the margins of the workbook. Locomotion and movement are made possible through the contraction and relaxation of muscles. Muscles are stimulated by nerves to contract. An innovative use of 3D printers to help repair fractures in bones! Rickets: This disorder is caused by a lack of vitamin D, calcium or phosphate which results in soft, weak bones.
A typical symptom in children who have rickets is a bowing bending outwards of the bones of the legs. Arthritis: This is a condition where the joints in the body become inflamed, painful and swollen. The cartilage between the joints breaks down causing the bones to rub against each other which is very painful. Osteoporosis : This occurs when the bone tissue becomes brittle, thin and spongy. These fragile bones can break easily, and they start to crumble and collapse. Although osteoporosis is common in older people especially older women , teenagers and young adults may also develop it.
An alternative to doing the summary diagram with the human body outline at the end of this system, is to get learners to produce a mind map. It is important that learners are exposed to and get experience with different techniques to summarise information and help them study or learn. This is crucial for later grades. Below is an example of a mind map that a learner may construct:. We will now be looking at the excretory system. This is often confused with egestion, which we previously learned about.
Do you remember learning about the difference between excretion and egestion? Explain what you understand the difference between these terms are.
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Egestion is the removal of undigested material solid waste from the digestive tract via the anus. Excretion is the removal of metabolic waste products from the metabolism which takes place in cells in the form of urine and sweat and exhalation. Our cells use oxygen and nutrients to function and in the process also produce various metabolic waste products including:. The organs of the excretory system are responsible for removing these harmful metabolic waste products from the blood so that they do not build up to high concentrations.
But, in the process, they have to retain the nutrients and water for the body to function. One of the main functions of the excretory system is to prevent too much or too little water in the body. We already know that the lungs excrete carbon dioxide CO 2 when you exhale. Another organ that excretes waste is the skin.
When you sweat, your skin excretes excess water, salts and a small percentage of urea. In this section, however, we will focus on the excretory system to remove metabolic waste from our blood in the form of urine. The kidneys filter all the blood in your body to remove urea from the blood.
You have two kidneys, each about the size of your fist and bean shaped. Your kidneys produce urine which is a combination of excess water and waste products. There are two ureters thin tubes which connect each kidney with the bladder and carry the urine from the kidney to the bladder. The bladder is a balloon-like organ that collects the urine before excreting it during urination.
The urethra is a tube that connects the bladder to the outside of the human body through which the urine is excreted. Filtration : All the blood in the body passes through the kidneys as part of the circulatory system. The kidneys filter the blood to remove unwanted minerals and urea, and also excess water. Some water is removed so that the metabolic waste products can be excreted in solution in the liquid urine. Your kidneys filter about ml of blood every minute!
Since you have about 7 to 8 litres of blood in your body, all your blood gets filtered 20 to 25 times per day through your kidneys! Absorption : Once the blood is filtered by the kidneys, the substances that the body needs are re-absorbed back into the blood so that they are not lost in the urine. Diffusion : The substances are transported into and out of the specialised cells of the kidney through the process of diffusion. Excretion : The kidneys funnel the liquid urine through the ureters to the bladder where it is stored.
When the bladder has filled up, it uses muscles to force the urine out of the body through the urethra. This is called excretion. Kidney Failure : When this happens the kidney loses its ability to properly filter and remove metabolic waste which allows this waste to build up in the body. This is very harmful and may be fatal. In such cases the patient needs to undergo very regular kidney dialysis. Dialysis involves using a machine which filters the blood for the patient to remove waste products. Bladder infection : This is one of the most common infections in women but is quite rare in men.
Bacteria can enter the bladder and cause an infection. This causes swelling and pain when urinating. Kidney Stones : Kidney stones form when fluid intake is too low, resulting in the concentration of solutes salts and minerals in the kidney becoming too high.
This can result in a small crystal stone forming. The kidney stone may stay in the kidney or move down the ureter to be excreted in the urine. A larger stone may however cause severe pain along the urinary tract and may even get stuck, blocking the flow of urine and causing severe pain or bleeding. A summary video of the excretory system.
A fun idea is to play the song of the nervous system in the visit box as learners come into the class and sit down. A song about the nervous system. Our nervous system is a complex network that transmits nerve impulses between different parts of the body. The nerves in our body receive stimuli from inside the body or from the environment from the ears, eyes, skin or tongue for instance. These are turned into impulses to the brain and spinal cord. Nerves are the long fibres which transmit messages from the brain and spinal cord to the rest of the body and back. Each nerve is actually an enclosed bundle of nerve cells, called neurons.
The nerves work together to carry messages throughout the body. They make up the nerve tissue in the nervous system. Your brain is located inside your skull. The brain is part of your central nervous system and sends messages to the rest of your body. There are different areas in the brain that have different functions.
All these different areas also communicate with each other. Citizen science: Play a game to help MIT map the brain! The spinal cord runs from the brain through your spine, protected by your vertebral column. The spinal cord is a bundle of nervous tissue and other support cells. Together with the brain, the spinal cord also forms part of your central nervous system. We have mentioned that there is a central nervous system made up of the brain and spinal cord. The second part of the nervous system within our bodies is the peripheral nervous system.
So the peripheral nervous system is on the outside of the central nervous system. The peripheral nervous system connects the central nervous system to the muscles and organs. Various sensory organs are responsible for collecting information and sending it via sensory nerves to the central nervous system.
Sending and receiving impulses: Nerve cells in the brain send and receive multiple messages from multiple sources at any given moment. These are transmitted as electrical impulses. The amount of electricity used by the brain to send and receive messages can power the light in your refrigerator! The central nervous system interprets these signals and this is how we sense the world around us. These processes are:. Want to learn more about the eye and sight? Regulating: An important part of the nervous system is to maintain a balance within the human body.
This includes regulating our body temperature.
If the body is too hot the brain might try and cool the body through increased sweating. If you are very cold, your body will start to shiver to generate heat energy. These responses to changes in body temperature are controlled by your nervous system. Trauma and injuries to brain and spinal cord: Any damage to the brain or spinal cord can have devastating effects on the human body. For example, people who break their necks in an accident, often damage their spinal cord.
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This prevents the brain from sending and receiving messages to the body and the person can become paralysed. Stroke: If blood flow to the brain is stopped, brain cells begin to die, even after just a few minutes without blood or oxygen. This can lead to a stroke where a part of the brain function is lost. Degenerative disorders: There are several problems associated with the nervous system that cause a gradual loss of function over time degenerative. Mental health problems: Examples include depression, anxiety disorder and personality disorders.
The Circulatory System: An Amazing Circuit That Keeps Our Bodies Going
Sensory organ problems: We have discussed the various sensory organs that are associated with the nervous system. These organs can also have problems, such as:. Teachers may want to use this opportunity to discuss the topic of drug abuse. If you would like to explain some of the effects of drugs and alcohol on the brain to your learners, here are some:.
It may be useful to explain to learners that the same drug may be useful and beneficial when used properly and at the correct dosage, or abused when it is used inappropriately, or in excessive amounts. Alcohol and drug abuse can cause irreversible brain damage, a loss of memory, decreased learning capability, an increased risk of strokes and heart attacks, and a variety of emotional and mental health problems. In humans, as in other eukaryotic organisms, the main purpose of the reproductive system is to produce sex cells to ensure the continuation of the species.
We will be looking at the reproductive organs in more detail in the next chapter. For now, let's get an overview of the main components in the reproductive system. The ovaries are located inside the female's body in the lower abdomen and produce mature egg cells ova. The largest cell in the human body is the ovum egg cell and the smallest cell is the sperm cell. The uterus also known as the womb is present in females. It has a thick lining and muscular wall. This is where a fertilised egg will implant and develop during pregnancy.
Some of the strongest muscles in the female body are found in the uterus! Can you think of reasons why this is?
The muscles in the uterus are some of the strongest in the human body. This is because they need to be able to grow and contract to contain a growing foetus and to push the foetus out during labour. The sex organs in males are located in the scrotum, a pouch of skin that hangs between the legs. During puberty the testes start to produce sperm cells. During sexual reproduction, the egg and sperm have to combine to form a new individual. Let's do an activity to find out about the main processes in the reproductive system.
As this will be dealt with in the next chapter, a simple activity can be done now for learners to look up these new terms and write down definitions. As the oxygen-rich blood arrives from the lungs, it enters the left atrium and then travels through to the left ventricle before being pumped throughout the body, according to NCBI. The blood gets pumped through the aorta artery the largest artery in the body before entering the smaller arteries that carry the blood to every part of the body. As the blood delivers nutrients and oxygen to each cell, carbon dioxide and other waste products are picked up as the blood flows through the capillaries and into the veins.
The contraction and relaxation of the heart — the heartbeat — is controlled by the sinus node, which is a cluster of cells situated at the top of the right atrium. The sinus node sends electrical signals through the electrical conduction system of the heart that direct the muscle to contract or relax.
The Circulatory System | Systems In The Human Body | Siyavula
The heartbeat is divided into two phases: the systole and diastole phases. In the first, the ventricles contract and push blood out into the pulmonary artery or the aorta. At the same time, the valves separating the atria and ventricles snap shut to prevent blood from flowing backwards. In the diastole phase, the valves connecting to the atrium open, and the ventricles relax and fill with blood. The sinus node controls the pace of these two phases. Adult humans have a total of about five to six quarts a little less than five to six liters of blood pumping through their bodies, according to Arkansas Heart Hospital.
On average, the heart pumps about , times per day, pushing about 2, gallons 7, liters of blood through a total of 60, miles 96, kilometers of blood vessels. It only takes about 20 seconds for blood to travel through the entire circulatory system.