brain lungs heart spleen stomach pancreas liver gallbladder kidneys small intestine large intestine bladder or urinary bladder the brain is the body's control center it's held and protected by the skull the cerebrum is the largest part of the brain it's divided into two halves called hemispheres the corpus callosum connects the two hemispheres each hemisphere is then divided into regions called lobes each lobe has a different function so here are the different parts of the brain the frontal lobe parietal lobe occipital lobe temporal lobe cerebellum and brain stem the brain is responsible for many different things including thinking decision making emotion memory speech production as well as muscle control coordination balance and sensory reception the frontal lobes are the largest lobes they're located at the front of the brain they're responsible for a few things this includes thinking self-control making decisions attention judgment problem solving planning and emotions the frontal lobe is also responsible for motor skills and speech production the parietal lobes are just behind the frontal lobe they're responsible for organizing and interpreting sensory information to other parts of the brain the occipital lobes are at the back of the brain they're mainly involved in visual processing including recognition of shapes colors patterns motion etc the occipital lobe is also involved in reading the temporal lobes are at the level of the ears they're responsible for processing auditory information visual memory verbal memory and language comprehension they're also involved in recognizing and understanding reactions and emotions of others the cerebellum is located at the back of the brain below the occipital lobes they're responsible for fine motor skills including fine movement of hands and feet the cerebellum is also responsible for balance coordination and posture the brain stem is located in front of the cerebellum and connects to the spinal cord it's made up of three major parts midbrain pons and medulla oblongata the midbrain is at the top of the brainstem it controls eye movement and it also processes visual and auditory information the pons is the largest part of the brainstem it's just below the midbrain it contains nerves that help to connect to different parts of the brain it also contains some cranial nerves which are involved in facial movement and for transmitting sensory information the medulla oblongata is the lowest part it controls the functions of the heart and lungs helping to regulate the function of things such as breathing swallowing sneezing coughing etc lungs lungs are part of the respiratory system the respiratory system works to provide oxygen into the bloodstream from the air which we inhale and releases carbon dioxide when we exhale this occurs automatically without you even having to think about it it's part of the autonomic nervous system the lungs have different parts to help take in air filter it and then oxygenate the blood the lungs fill the chest cavity they are held and protected by the rib cage the trachea splits into tubes and extend into each lung these are two bronchi the right and left bronchi each bronchi enters each lung the smaller bronchi then splits into even smaller tubes called bronchioles the bronchioles end with tiny sacs called alveoli they are surrounded by a network of blood vessels called capillaries now let's go through the process of breathing in when you inhale the air you breathe in travels through your nose or mouth down the trachea the air then travels through the bronchi into each lung from here the air travels through the bronchials into the alveoli alveoli expand when a person inhales and contracts when a person exhales alveoli are surrounded by a network of blood capillaries this is where the exchange of oxygen and carbon dioxide takes place the alveoli have a large surface area thin walls and a good blood supply which allows the diffusion of these gases oxygen diffuses out of the alveoli and into the blood this blood is then carried throughout the body via the blood vessels carbon dioxide diffuses out of the blood and into the alveoli the carbon dioxide received into the lungs is then exhaled heart the heart is a vital organ providing blood to the body it's part of the circulatory system made up of the heart blood vessels and the blood humans have a double circulatory system in the first circuit deoxygenated blood is pumped to the lungs to be oxygenated and then returns to the heart in the second circuit oxygenated blood is pumped around the body by the heart and blood vessels the heart is located in the ribcage near the lungs the heart continuously pumps in a consistent rhythm electrical impulses in the heart ensure it beats with a constant rhythm and rate the heart rate can increase or decrease depending on how much blood the body requires for example when you're exercising the heart beats faster in order to pump more blood around the body whereas when you're resting the heart beats slower the heart has four chambers the small upper chambers are called atria and the lower chambers are called ventricles so here right atrium left atrium right ventricle left ventricle the heart also has four vowels these are like little doors which only open one way this ensures that the blood is flowing in the right direction and doesn't flow backwards tricuspid and pulmonary valve are on the right the mitral and aortic valves are on the left it's important to remember that veins carry blood to the heart and arteries carry blood away from the heart the superior and inferior vena cava are large veins that deliver deoxygenated blood into the heart the superior vena cava delivers blood into the heart from the superior part of the body this includes the head neck arms and chest the inferior vena cava delivers blood into the heart from inferior parts of the body this includes organs in the abdomen legs feet etc the pulmonary vein carries oxygenated blood from the lungs to the heart the aorta is the main artery that carries oxygenated blood away from the heart to the rest of the body the pulmonary artery carries deoxygenated blood from the heart to the lungs now let's go through the full process deoxygenated blood from the body flows into the right atrium via the superior and inferior vena cava the right atrium contracts and the blood flows through the tricuspid valve into the right ventricle the ventricle contracts and the blood flows up through the pulmonary valve into the pulmonary artery this is then taken out of the heart into the lungs at the same time the oxygenated blood from the lungs enters the heart through the left atrium via the pulmonary veins the left atrium contracts and blood then flows through the mitral valve into the left ventricle the left ventricle contracts and oxygenated blood flows up through the aortic valve into the aorta this blood is then sent around the body via arteries remember in one heartbeat blood enters and exits the heart from both sides diastole is when the heart relaxes and fills with blood both the right and left atrium fill with blood systole is when the heart contracts and pumps blood both the right and left ventricles pump blood into the arteries this process then repeats the heart itself also needs a constant supply of oxygenated blood to function the coronary arteries that branch off the aorta supply this these are wrapped around the outside of the heart here is a diagram illustrating diastole the heart is relaxed and the heart fills with blood as you can see the heart receives blood through the veins into both atria following atrial systole the blood is pushed into the ventricles ventricular systole occurs in which the blood is pushed into the arteries and out of the heart spleen the spleen is a small organ behind the stomach under the lungs the spleen stores blood and filters it it's able to recognize old or damaged blood cells and the spleen is also able to break down and remove them out of the body this means that clean and well-functioning blood is able to circulate around the body the spleen also helps to filter out infections by creating white blood cells to fight bacteria and viruses therefore it's a small but very important organ in our body stomach the stomach lies beneath the diaphragm it's a j shaped organ it plays a role in digesting food the stomach is divided into five parts the cardia is just beneath the esophagus sphincter muscles prevents food from flowing back up to the esophagus or mouth the fundus is to the left of the cardia the body is the main part of the stomach where food is broken down the pyloric antrum is the lower part of the stomach partially digested food is kept here before it flows to the small intestine the pyloric canal is a small part of the stomach that connects to the first part of the small intestine it contains the pyloric sphincter helping to control how much content flows into the small intestine the stomach contains muscles and gastric juices the muscles of the stomach help to change the size depending on how much food there is for example if you've eaten too much food then it will expand the muscles in the stomach also help to break down the food gastric juices in the stomach help to kill bacteria and contains enzymes together the muscles and gastric juices help to break down food thoroughly when you swallow food it enters the cardia of the stomach the fundus adapts to how much food is entering the stomach it expands as the amount of food increases the body of the stomach produces gastric juices which mixes with the food the stomach's muscles contract to help mix and break down the food the food then exits the stomach via the pylorus into the first part of the small intestine pancras the pancreas sits behind the stomach and it has two functions exocrine function and an endocrine function the exocrine function is to help with digestion the endocrine function is to regulate blood sugar the pancreas's exocrine glands produce enzymes which help with digestion the enzyme amylase breaks down carbohydrates the enzyme lipase breaks down fats the enzyme protease helps to digest proteins the pancreas also produces pancreatic juice this further helps with digestion the food is digested and converted into energy this energy is then released into the bloodstream for the body to use the endocrine function is to regulate blood sugar the pancreas produces and releases insulin and glucagon when there's too much sugar in the blood the pancreas produces and releases insulin into the blood this helps to remove glucose by converting it into energy and releasing it into the blood this energy can also be stored for later use when blood sugar is low the pancreas produces and releases a hormone called glucagon this tells the cells and liver to release the stored sugar back into the blood liver the liver plays a vital role in the body's metabolic system the liver processes contents of the blood to ensure the composition stays the same the liver does this in many different ways the organ is located just under the rib cage on the right upper side of the abdomen near the gallbladder the liver is supplied with oxygenated blood via an artery the liver has many functions the first is to purify blood it receives from around the body the nutrients received in the blood from around the body is processed by the liver and broken down these include fats carbohydrates vitamins minerals etc the liver ensures a good and constant level of nutrients are in the body for example the liver breaks down carbohydrates into sugar depending on the body's needs the liver will send this sugar back to the body to be used as energy or it stores some nutrients that are left over if the body doesn't need them straight away the stored nutrients can then be used later on when the body needs it the blood going into the liver sometimes contains toxic substances or substances that are useless to the body so the liver detoxifies toxic substances so it doesn't cause harm to the body it also metabolizes drugs for anything else that's useless to the body the liver removes it via excretion the liver produces plasma proteins and blood clotting factors these clotting factors prevent the body from losing too much blood the liver also produces cholesterol cholesterol is important for cell structure it also produces hormones vitamin d and other substances another role of the liver is that it produces bile this is a fluid released by the liver and stored in the gallbladder the gallbladder is a small green pouch found just under the liver the production of bile helps with digestion and breaks down fats into fatty acids this allows it to be taken into the small intestine for digestion bile also helps to destroy bacteria helping to fight infections therefore the liver is a vital organ with many important functions gallbladder the gallbladder is a small green pouch found just under the liver one of the functions of the liver is to produce bile this is a fluid released by the liver and stored in the gall bladder the production of bile helps with digestion and breaks down fats into fatty acids this allows it to be taken into the small intestine for digestion bile also helps to destroy bacteria helping to fight infections kidneys kidneys are two bean-shaped organs the kidneys maintain the body's chemical balance they do this by filtering the blood and excreting waste products as well as excess fluid as urine the kidneys are protected by the lower part of the ribcage kidneys receive unfiltered blood from the renal artery each kidney contains millions of tiny units called nephrons these are used for filtration the kidney identifies useful and waste products in the blood for example if vitamins and minerals are required by the body then the kidney will allow these to flow back to the body the filtered blood returns back to the body via the renal vein any excess water and waste leaves in the form of urine narrow tubes called ureters carry the urine into the bladder to be released so here we have the kidneys the narrow tubes extending from the kidneys are called ureters and these carry urine into the bladder alongside filtering blood and producing urine the kidneys also detect body's water level so if you drink too much water then the kidneys detect this and will release it through the bladder as urine this is why when you're well hydrated your urine color is lighter if you don't drink enough water the kidneys will also detect this and will release some water back into the bloodstream this is why when you're dehydrated your urine color is yellow the kidneys also secretes hormones for example a hormone to increase red blood cell production or a hormone to increase blood pressure lastly the kidneys activate vitamin d remember we have two kidneys however a person can live fine with just one kidney small and large intestines intestines are groups of tubes that digest food filter out the body's waste and absorb water food that's broken down from the stomach travels to the small intestine this is where most of digestion and absorption of nutrients takes place this food then passes through the large intestine water and salt is absorbed here this causes the waste products to turn into a solid waste material which can then be excreted bladder the bladder is part of the urinary tract system this also includes the kidneys ureta bladder and urethra kidneys receive unfiltered blood from the renal artery the kidneys then work to filter the blood by identifying useful and waste products in the blood for example if vitamins and minerals are required by the body then the kidneys will allow these to flow back to the body the filtered blood then returns back to the body via the renal vein the waste products and excess fluid in the blood is removed and released as urine the urine produced travels down the uretas of each kidney into the bladder the bladder is made up of muscle and its primary role is to store urine it can stretch and contract the bladder also contains valves to prevent the urine from flowing back up to the urethras it stretches to store the urine and then contracts when releasing urine via the urethra if you drink too much water then the kidneys detect this and will release it through the bladder as urine this is why when you're well hydrated your urine color is lighter if you don't drink enough water then the kidneys will also detect this and will release some water back into the bloodstream this is why when you're dehydrated your urine color is yellow you