All muscles get shorter and pull so they can’t work alone. Most muscles work in opposing teams.
Voluntary & involuntary muscles
Voluntary – muscle movements controlled by thoughts
Skeletal System
Four prime functions
Protect vital organs
Gives our shape
Allows us to move
It builds blood cells
Ligaments – hold bones together
Circulatory System
4 to 5 liters of blood
Two major parts
Heart pumps deoxygenated blood from body to the lungs
Heart pumps oxygenated blood from the lungs to the body
Respiratory System
Breathing – take in oxygen & removes carbon dioxide
Air travels down the trachea (windpipe); divides into two tubes called bronchi going into each lung; divides further into smaller tubes called bronchioles; at the end of these tubes are air sacs called alveoli; capillaries are wrapped around these alveoli to transfer oxygen & carbon dioxide
Nervous System
Brain
Nerves
Nerve Cell (neuron)
Digestive System
Starts in the mouth, ends at the anus
Mouth – 6 salivary glands
Esophagus – muscular tube that takes food to stomach
Stomach – mash food & digest juices break down food
Pancreas – breaks down food even further with enzymes before it enters the small intestines
Gall bladder – stores bile, made by the liver. As food enters the small intestines, bile is added to digest fatty foods & also contains waste for removal
Small intestines – nutrients pass through into the blood, where they are carried to the liver and other body parts to be processed, stored, or distributed
Liver – blood from the intestines enters the liver. The liver determines what the body needs and releases or stores it accordingly
Large intestines – some absorption of water & minerals
Rectum – storage of feces
Anus – exit feces from body
Immune System (defense against germs)
Skin
Breathing and digestive pathways
White cells – attack germs in the body
Thymus gland
Lymph nodes – contain white cells
Spleen
Phagocytes – germ eating white cells
Stores red blood cells
Filters blood
Endocrine System
Information Signal System made up of glands that mainly use hormones as information channels
Pituitary gland – affect & control functions such as skeletal growth, development of sex glands, blood pressure & pain relief
Thyroid – controls how quickly the body uses energy & regulates metabolism
Adrenal gland – synthesizes and releases hormones in response to stress