Human Body Systems

Dalton Wilcox

Digestive System

The function of the digestive system is digestion and absorption. Digestion breaks down the food we consume into tiny molecules and absorption is where the molecules are absorbed into the body.
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Structures of The Digestive System

The Mouth- The mouth is the beginning of the digestive system. The mouth mechanically breaks down the food with chewing as well as chemically breaks food down with saliva.

The Esophagus- The esophagus receives broken down food from the mouth and transports it to the stomach.

The Stomach- The stomach breaks down the food further through digestion. It secretes a strong acid that breaks down the food into a thick liquid.

The Small Intestine- Using enzymes the small intestine breaks down the food further and is responsible for absorption of nutrients into the bloodstream.

The Large Intestine- The large intestine absorbs the left over water and transports waste to the rectum once absorption is complete.

The Rectum- The rectum receives defecation from the colon.

The Pancreas- The pancreas secretes enzymes. These enzymes are responsible for the breakdown of proteins, fats, and carbohydrates.

The Liver- The liver secretes bile which is a substance that processes the blood from the small intestine containing the nutrients from digested food.

The Gallbladder- The gallbladder absorbs the left over bile secreted from the liver.

Major Disorders


Appendicitis is the swelling of the appendix when it is blocked. Symptoms include pain in the area of the appendix, loss of appetite, fever, nausea, and vomiting. The only treatment for this is surgery to remove the appendix.

Cystic Fibrosis (CF)

Cystic Fibrosis or CF, affects the pancreas. Mucus from CF blocks the ducts in the pancreas the secrete enzymes. With the ducts block, food cannot be properly digested therefore less nutrients are absorbed into the body. Symptoms include coughing that results in thick mucus, and feces that is thick and smells horrid.

Pyloric Stenosis

Pyloric Stenosis occurs when the opening from the stomach to the intestine is blocked. Symptoms include projectile vomiting, constant hunger, fewer and smaller feces, weight loss, and dehydration. Similar to appendicitis, the only known cure to this disorder is surgery.

Excretory System

Excretion is defined as the process of eliminating or expelling waste matter. The excretory system is the system responsible for disposing of waste produced by homeostasis.
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Major Disorders


Nephritis is the inflammation of the kidneys. It is caused by inflammation of the glomerulus. Symptoms include Blood in urine, pain in the lower abdomen, and smelly urine. Antibiotics can be used to cure nephritis.

Kidney Stones

Kidney stones are built up calcium masses that are passed through the urinary tract. While extremely painful, kidney stones if small enough can be passed through the urinary tract without medication or surgery. Symptoms include vomiting, painful urination, blood in the urine, and fevers.


Cystitis is the inflammation of the bladder. Mostly caused by bacterial infection, cystitis can be cured with prescribed antibiotics. Symptoms include Pain when urinating, difficulty urinating, cloudy urine, or blood in the urine.

Circulatory System

The circulatory system is responsible for the transport of nutrients, water, and oxygen to your cells.
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Structures of The Circulatory System

The three main structures of the circulatory are arteries, veins, and capillaries. Arteries carry the blood away from the heart while the veins carry blood back to the heart. Capillaries connect arteries to veins. Nutrients, oxygen, and waste pass from the blood through the capillary wall.

The Route of Blood Through The Heart

Blood enters the heart through both venae cavae and the coronary sinus. It then goes through the right atrium to the tricuspid valve and then the right ventricle. After the right ventricle the blood goes through the pulmonary valves to the pulmonary trunk. Once the blood passes the pulmonary trunk, it moves to the right and left pulmonary arteries then to the lungs where the blood cells pick up oxygen. It is the taken back to the heart by the pulmonary veins then through the left atrium. From the left atrium the blood goes to the mitral valve into the left ventricle then to the aortic valves. Once through the aortic valves the blood continues to the aorta then is distributed to the body.

Blood Composition

Blood Plasma- Blood plasma is a mixture of proteins, enzymes, nutrients, gasses, waste, and hormones.

Red Blood Cells- The red blood cells transport oxygen from the lungs to tissue and also transport carbon dioxide from the tissue to the lungs

White Blood Cells- White blood cells fight off sicknesses

Platelets- When your skin is cut the platelets for a scab to stop the bleeding.

Major Disorders

Aortic Aneurysm

An aortic aneurysm is caused from the weakening of the aortic wall, causing a bulge called an aneurysm. Aortic aneurysms do not cause symptoms a treatment if necessary is surgery.

Deep Vein Thrombosis (DVT)

DVT is when blood clots form in deep veins such as veins in the thigh or calf. Symptoms are minimal, pain is typically the only system. Treatment is surgery.

Respiratory System

The respiratory system supplies the blood with oxygen through breathing so the blod can transport oxygen to the rest of the body.

Features of Alveoli

The alveoli are tiny sacs on the lungs that assist in gas exchange. On the surface, gas is taken in and diffused to the capillaries. Capillaries help get the gasses to thee blood.

Movement of Gas

Oxygen enters through the right side of the alveoli, then diffused into the blood. Carbon dioxide is diffused from the blood then exits through the left side if the alveoli.
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Major Disorders


Bronchitis is the result in any irritant reaching the bronchi. The result is extreme coughing due to secretion of mucus. It can be cured with medication.


Asthma is the periodic obstruction of the bronchi holes due to swelling caused by allergens. Asthma causes difficulty breathing and is subsided by an inhaler.

Immune System

The immune system is the bodies protection. It fights of sickness and disease.
Pathogens- Pathogens are any bacteria, virus, or microorganism that causes disease.

Active Immunity- The immunity that results from the production of antibodies.

Passive Immunity- The short term immunity from the introduction of antibodies.

Antigen- Antigens are any toxins that induce production of antibodies.

Antibody- A protein produced in blood made to fight off any alien sicknesses.

Effects of Antibiotics

Antibiotics are made specifically to fight bacterial infections. Since they are made for bacterial infections, they are ineffective against viral infections.

Major Disorders


Lupus is an autoimmune disease that attacks body tissues including lungs, kidneys, and skin. The cause is unknown and can be treated by prescription drugs.


HIV/AIDS is a viral disease which destroys white blood cells. It is sexually transmitted and cannot be cured.

Endocrine System

The endocrine system is made up of glads which secrete hormones that regulate growth, metabolism, and sexual reproduction.

Homeostasis in the Endocrine System

Homeostasis is defined as the tendency toward a relatively stable equilibrium between interdependent elements, especially maintained by physiological processes. It plays a major role in the endocrine system by maintaining stability in the body using glands.

Negative Feedback

Negative feedback assists in homeostasis. An example would be body heat. If you get too hot, you sweat. If you become too cold, you shiver. These are both forms of negative feedback.

Major Disorders

Type I Diabetes

Type I diabetes is the failure of the pancreas to produce insulin. Systems include sweating, nausea, excessive thirst and hunger, and fatigue. Type I diabetics typically get regular insulin shots to maintain homeostasis.

Type II Diabetes

Type II diabetes is the failure of the body to process blood sugar correctly. Symptoms include fatigue, excessive hunger, and increased thirst.

Skeletal System

The main functions of the skeletal system are to support the body, provide structure, store calcium, and assist in movement and blood cell reproduction.
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Structures of The Skeletal System

Bones- Bones provide structure, protection, and assist in movement of the body.

Ligaments- Ligaments connect one bone to another forming joints. They also keep the bones from moving in a direction which could damage a joint.

Muscles- Muscles contract and stretch to move other parts of the body.

Tendons- Tendons connect muscle to bone.

Nerves- Nerves transmit signals to the brain.

Major Disorders


Arthritis is the swelling of joints. It is caused by many other diseases like gout, tuberculosis, and other infections.


Rickets is the bowing of legs in young children caused by insufficient calcium and vitamin D. It cannot be cured.

Muscular System

The muscular system is responsible for the movement of the body.

Muscle Contraction

Calcium floods into the muscle, actin and myosin bind to create cross-bridges and use ATP to contract the muscle.

Major Disorders

Muscular Dystrophy

Muscle Dystrophy is the weakening of muscles in mothers due to lack of protein that holds skeletal muscles together. Symptoms are essentially difficulty moving period and there is currently no cure.


Ataxia is the lack of coordination in voluntary muscle movements. It is caused by damage to the cerebellum and there is no cure.

Nervous Syestem

The nervous system is responsible for movement of the body and communication of body parts.

Central Nervous Syestem

The central nervous system is responsible for integrating sensory information and responding accordingly. It is composed of the brain, and spinal cord.

Peripheral Nervous System

The peripheral nervous system is responsible for connecting the central nervous system to the rest of the body through nerves and ganglia.
Cerebral Hemispheres- The cerebral hemispheres are the highest level of the nervous system. The right hemisphere controls the left side of the body, while the left hemisphere controls the right side of the body.

Diencephalon- The diencephalon is the area above the brain stem containing the thalamus, hypothalamus, pituitary gland, an the pineal gland.

Brain Stem- The brain stem regulates heart rate, breathing, sleeping, and eating.

Cerebellum- The cerebellum controls basic motor functions of the body.

Major Disorders

Parkinson's Disease (PD)

Parkinson's disease or PD is the difficulty in body movement due to the lack of the brain producing dopamine. Symptoms include trembling hands, stiffness in the arms legs and torso, and poor balance. This disease can be controlled but not cured.

Alzheimer's Disease

Alzheimer's disease is a genetic disease caused by dementia. It is the deterioration of nerves in your brain causing severe memory loss.

Reproductive System

The reproductive system is responsible for producing new life through sexual reproduction.


Spermatogenesis is the process in which male sperm are created from male primordial cells by mitosis or meiosis.


Oogenesis is the production and growth of the immature egg in the female reproductive track.

Major Disorders


Virilization is the hormonal imbalance in females that causes male characteristics to be present. The main symptom is excessive body hair and it can be cured through medication.

Prostate Cancer

Prostate cancer is just as it sounds, cancer of the prostate. It is the most common cancer in men and can be cured like any other known cancer.