Biology- Mr. Willets

Digestive System

Function- break apart large molecules (macromolecules) so that they can enter the blood and get into the cells

a) mouth- chewing breaks food apart, enzymes in saliva start digesting starches into sugars

Mechanical digestion / chemical digestion

b) pharynx (throat) - pushes food into esophagus

c) esophagus- muscle contractions (peristalsis) pushes food into stomach- "heartburn" occurs here when stomach acid enters the esophagus.

d) stomach- food is ground up more, enzymes digesting protein are added (these work better in acid conditions)

e) small intestines- enzymes from pancreas, liver and small intestinal cells are added and digest starches, fats and proteins. Digested food is absorbed into the blood capillaries through small intestines walls.

Bile- made in liver- stored in gall bladder- helps fats mix with water

f) large intestines (colon)- water is absorbed into the blood here

g)rectum- undigested food (feces) are stored here

h) anus- opening through which feces leave the body.

Circulatory System

Function- to carry materials around the body: especially food, oxygen and wastes

a) heart- pumps the blood

b) blood- mostly water with some cells. Liquid part of the blood- plasma

Red blood cells contain the chemical hemoglobin which carries oxygen.

White blood cells- fight disease

Platelets control clotting

c) arteries- blood vessels that carry blood away from the heart. Pressure is high in arteries. Pulse is felt in arteries. Blood in most arteries is high in oxygen. Aorta- largest artery in the body

d) veins- blood vessels that carry blood back to the heart. Blood pressure is low in veins. Blood in most veins is low in oxygen.

e) capillaries - very small blood vessels that connect the arteries to the veins. Materials enter and leave the blood through the thin capillary walls.

Kidneys- although part of the excretory system, the kidneys work closely with the blood. As blood passes through the kidneys, wastes are removed from the blood and sent to the bladder to be stored until released from the body. The most common wastes removed by the kidney are nitrogenous wastes produced when amino acids are deaminated (nitrogen removed).

Liver- another organ that works closely with blood. The liver is the toxic waste dump of the body. It removes many chemicals from the blood that do not belong there including useful drugs. The liver "de-toxifies" these chemicals and then puts them back into he blood for the kidneys to remove

Respiratory System

Function- to bring in oxygen and get it into the blood and to remove carbon dioxide (the exchange of gases)

a) nose- warms and filters the air

b) pharynx (throat)- connects nose and mouth to trachea

c) trachea- tube that leads to the lungs. It is kept open by rings of cartilage. The epiglottis covers the opening to the trachea when you swallow to avoid choking..

d) larynx- the voice box. Vocal cords are here. Your Adam's Apple is the larynx.

e) Bronchi- trachea splits into 2 bronchi which go to the lungs. These branch into smaller and smaller bronchial tubes. Each bronchial tube ends in a alveolus.

f) lungs-these are very spongy and can expand greatly when air is brought is. They contain millions of alveoli

g) alveoli- air sacs. Millions of them in each lung. Very thin walls with capillaries around them. Oxygen enters the blood and carbon dioxide leaves the blood through the walls of the alveoli.

h) diaphragm- muscle that pumps air in and out of lungs

Muscular System / Skeletal System

Function- support and movement

a) skeletal muscle- also called voluntary muscle. You consciously control these muscles. They are attached to bones by tendons. These muscles allow you to move.

b) smooth muscle - also called involuntary muscle. These work automatically and are found in various organs like the stomach, intestines.

c) cardiac muscle- found only in the heart.

d) tendons- connect muscle to bone

e) ligaments- hold bones together

f) cartilage- used as a cushioning material in joints. End of nose, ears and ends of ribs are made of cartilage

g) bones- made of minerals that contain calcium and phosphorous. Bones also have bone cells which make the bone material and bone marrow which makes red and white blood cells. Bones have capillaries running through them.

Nervous System

Function- to sense the environment, both internal and external; send messages to and from the brain.

a) brain- receives sensory information ; controls muscles and internal organs; memory, creativity, thinking etc.

b) spinal cord- connect brain to the rest of the body. Some nerves go directly from brain to specific places.

c) neuron- nerve cell. It has fibers that extend from the main body of the cell. These fibers connect one neuron to another. Neurons works using charged particles that enter and leave the fibers (electrochemical signals). Messages are sent from one neuron to another using chemicals called neuro-transmitters.

d) sensory neuron- this type of neuron senses the environment and sends messages to the brain through the spinal cord.

e) motor neuron- this type of neuron brings messages from the brain to the various body parts.

f) nerve- a nerve is a bundle of nerve fibers

g) associative neuron- this type of neuron is found in the brain and spinal cord and connects sensory and motor neurons.

h) hormones- chemicals released by endocrine glands that affect body functions. These travel through the blood and can affect specific parts or large areas of the body. Messages from the brain control the release of these chemicals.

NOTE-

All these systems interact with each other to help maintain homeostasis within the body.