Smooth muscles are also known as involuntary muscles, meaning that a person cannot physically chose to move them. Instead, smooth muscles are controlled in the background by brain and body. An example of smooth muscle is the digestive system, where muscles in the contract to squeeze food down to the stomach or tighten when you have an illness so that you are sick. Other examples of smooth muscle include the bladder and the muscle behind the eyes that keeps your eyes focused. Smooth muscles are also found in the blood vessels, helping blood to move around the body.
Cardiac muscle is in your heart, also known as myocardium. Like smooth muscle, cardiac muscle is an involuntary muscle. These muscles are thick because they have to contract frequently to move blood in and out of the heart.
Skeletal muscles are the muscles that allow you to control the movements of your body, arms and legs, etc. These muscles are attached to your bones via tendons, which are like cords made of tissue. In order for you to move, your skeletal muscles, tendons and bones must all work together. Skeletal muscles come in different shapes and sizes – just compare the muscles of a weight lifter to your own!.
Other skeletal muscles in the body you may not be as aware of include those in the neck or face. Even your tongue contains skeletal muscles. Skeletal muscles often work in pairs, such as the biceps, which bend the arms, which work with the triceps, which straighten the arms.
In the video when the biceps contract the arm bends, when the triceps contract it straightens out again…
The adults human skeleton consists of 206 bones. There are more bones present at birth but they gradually fuse together as the body matures. The skeleton is divided into two parts.
The axial skeleton includes the bones of the skull, face and spine along with the ribs and breastbone.
The appendicular skeleton includes the bones of the arms, hands, legs, feet and pelvis as well as the clavicles and shoulder blades. The skeleton serves several vital functions.
The skeleton gives the body its shape, which changes with growth. It determines height, the size of the hands and feet, it keepsbody shape stable and enables essential functions such as breathing – a stable rib cage and spine enable the lungs to fully inflate fully.
The skeleton gives support to the body and keeps the internal organs in their correct places. The strong bones of the spine, pelvis and legs allow people to stand upright, supporting the weight of the entire body. The skull holds the brain, the chest cavity houses the heart and lungs, and the abdominal cavity maintains the organs of the digestive, urinary and internal reproductive systems.
Bones are held together by ligaments. Tendons attach the muscles to the bones of the skeleton. The muscular and skeletal systems work together to enable the body to move and remain stable. When muscles contract, they pull on bones of the skeleton to produce movement or hold the bones still in one position.
The shape of the bones and the way that they fit together at the joints allows for different types of movement. For example, the leg bones come together at the knee to form a hinge joint that enables the knee to bend back and forth. The joining portions of the bones of the hip and shoulder have a much different shape and form ball-and-socket joints that allow movement in multiple directions.
The skeleton protects the internal organs from damage by surrounding them with bone. Bone is living tissue that is hard and strong, yet slightly flexible to resist breaking. The strength of bone comes from its mineral content, which is primarily calcium.
Examples of the protective bones of the skeleton include the skull, spinal column and rib cage, which protect the brain, spinal cord, and heart and lungs.
5. Blood Cell Production
Larger bones contain bone marrow Marrow is responsible for production of all of the body’s red blood cells and many of its white blood cells. Red blood cells are produced at an average rate of approximately 200 million per day. These cells carry oxygen to the body tissues.
The marrow is found mainly in the breastbone, hips, ribs, skull, spinal bones and at the end of long bones of the arms and legs. Several types of white blood cells, which protect the body from infections, are also produced in red bone marrow.
The digestive system consists of aseries of organs and glands that process the food we eat in order to convert food into energy. The body needs to break food down into smaller molecules that it can utilise the nutrients in food before excreting (getting rid of) the unusable components of food as waste.
Most of the digestive organs (like the stomach and intestines) are tube-like and contain the food as it makes its way through the body.
The digestive system is essentially a long, twisting tube that runs from the mouth to the anus, plus a few other organs (like the liver and pancreas) that produce or store digestive chemicals.
Without the digestive system, our bodies would not be able to get nutrients from the food we eat or get rid of the waste products that food makes and we would soon become ill!
Find out loads more about the digestive system here…
Healthy teeth are really important for our overall health. They help us to smile and speak and bite and chew the food we need to sustain ourselves. It’s important to understand the different types of teeth you have throughout your life.
Milk teeth are the first teeth we get as babies. These teeth start developing before a baby is born and will normally start to come through when an infant is between 6 and 12 months old.
By the time a child reaches 3 years of age it they can expect to have a full set of 20 milk teeth. They will keep this set for another few years and keeping these teeth healthy and clean will help them to eat, talk and avoid problems when the adult teeth grow in.
When a child reaches the ages of between 5 and 6 their milk teeth should start to gradually fall out with adult teeth growing in shortly after.
Read more about caring for your baby’s first teeth and teething
Between the ages of 12 and 14 a you will have lost all of your baby teeth and these will have been replaced by a full set of adult teeth.
A full set of adult teeth consists of 32 teeth in total. This includes the wisdom teeth, which grow in at the back of the mouth. These normally grow in much later and can be expected between the ages of 17 and 21. For some people wisdom teeth don’t grow in at all.
The different types of teeth
Incisors are used for chopping and cutting food into small chunks, these are your front teeth and you have 4 on the bottom and 4 on the top.
Canine teeth help you to tear chewy food such as meat. You have 2 of these in the top jaw and 2 in the bottom jaw and they are positioned next to your incisors.
Premolars are positioned next to your canine teeth. A full set of adult teeth will normally contain eight premolars with 4 on the top and 4 on the bottom row of teeth. We rely on these teeth for grinding and crushing chunks of food. These teeth are bigger and wider with a flat surface area on the bottom unlike your narrow and sharp front teeth.
Molars grow in at the back of your mouth and a full set of adult teeth should have 8 in total with 4 on the top and 4 on the bottom jaw. These teeth are your strongest and we rely on these teeth to grind our food so it’s safe to swallow
Arteries take blood away from the heart to the body organs and tissues. The artery wall is thick and muscular so it can withstand the high pressure of the blood being pumped directly from the heart
Capillaries are tiny, thin-walled vessels which form a network to take blood through the organsand tissues
Veins collect blood from the capillaries in the body and return the blood to the heart. The wall of the veins are thin, the blood is at a much lower pressure. To prevent the backflow of this lower pressure blood the veins contain valves.
You can feel a pulse in your wrist. This is the surge of blood that happens when your heart beats and pumps blood round your body.
blood is pumped from the heart to the lungs where it absorbs oxygen breathed in from the air. The blood transports that oxygen down arteries to the muscles and organs where it absorbs waste carbon dioxide.
The blood returns to the heart through the veins and is then pumped back to the lungs where it releases the carbon dioxide to be breathed out and absorbs more oxygen to continue the cycle.
Plasma contains contains electrolytes, nutrients and vitamins and hormones as well as red blood cels, white blood cells and platelets.
Red blood cells carry oxygen from your lungs to your heart, and then to your muscles. They help to remove the carbon dioxide from the body. They contain haemoglobin, a substance which loves to combine with oxygen. Red blood cells deliver oxygen round the body.
White blood cells produce antibodies to fight infections White blood cells are clever – white blood cells called lymphocytes can produce “memory cells” to remember how to fight an infection so that if the body is infected again it can fight it quickly.
Platelets help the blood to clot if you get a cut…