Human Body Systems

1. The Circulatory SystemPurpose of the system: transport food,

oxygen, waste and hormones. We have a closed system (all blood is in vessels)

Heart-about the size of your fist, it is a 4 chambered pump, upper chambers are called atria and bottom chambers are called ventricles.

VesselsVein-a vessel going to the heart, has thin walls

Artery-vessel going away from the heart, has thicker walls

Capillary-smallest vessel, has walls one cell layer thick, where the exchange of oxygen and CO2 takes place.

Blood is mostly water (plasma) it carries cells and dissolved materials

RBC- cells that carry oxygen

WBC-cells that fight infection

Platelet-cell fragments that clot blood

Blood pressure-push of blood against artery walls. Recorded when heart is pumping and when it is relaxed.Normal is 120/80

                                                                                                                                                

Interesting facts about the circulatory system:

1. Our bodies contain 60,000 miles of blood vessels

2. Adults have 10 pints of blood

2. The Respiratory System

Purpose of the system: to exchange carbon dioxide and oxygen

Nose-warms, filters, moistens airPharynx-throat (where nose and mouth

combine)

Larynx-contains vocal cords, as air goes past they vibrate and we can form sounds

Trachea-windpipe, carries air to lungs

Bronchi-branches of the trachea

Lungs- spongy tissue made up of millions of air sacs

Alveoli- air sacs

Normal lung Smoker’s lung

Diaphragm-breathing muscle, located under lungs, it changes the size of the chest cavity pulling in or pushing out air

Interesting facts about the respiratory system:

1. A sneeze has a speed of 102 mph

2. You have 300 million alveoli, flattened out that is the size of a tennis court

3. The Muscular SystemPurpose of the system: movement (of the body, blood,

and food)

40% of the body is muscle.There are approximately 600 muscles in the body

There are 3 types of muscle tissue:1. Smooth

-not under voluntary control-has one nucleus-not striped -found in walls of hollow structures (like the stomach)

2. Cardiac-found only in the heart-striated (striped)-not under voluntary control

3. Skeletal-attached to bone-under voluntary control-striated-large cells with many nuclei

Antagonistic musclesmuscles that cause the opposite action of another muscle

example: bend arm up (biceps) bend arm down (triceps)

Interesting facts about the muscular system:

1. Eye muscles are the busiest in the body. It is estimated that they may move 100,000 times a day.

2. Muscles can’t push, they can only pull

4. The Digestive SystemPurpose of the system-to turn food into a

usable form for cells to get energy from

Structures:Mouth-teeth make food smaller, saliva moistens food, starches get broken down here

Esophagus-a muscular tube that pushes food to the stomach

Stomach-a muscular sac that mixes digestive juices with food.

Proteins are digested here, food averages 3 hours in the stomach.

Liver-large structure that makes bile which breaks down fats

Gall bladder-small sac under liver that stores bile until needed

Pancreas-located under stomach, it adds digestive enzymes to the small intestine

Small intestine-long tube (25 ft. in an adult) where fats get broken down and food is absorbed into the blood.

Large intestine-(colon) shorter tube (5 ft.) that removes water from waste and gets it ready to eliminate.

Interesting facts about the digestive system:

1. In your lifetime your digestive system will break down as much as 35 tons of food (that is 10 elephants)

2. A horse’s digestive tract is 89 ft. long3. Americans eat 2 billion pounds of

chocolate a year

5. The Skeletal SystemPurpose of the system: bones protect

organs, give us shape, store minerals, make blood cells

Bones-the organs of the skeletal system, there are 206 in the body

Marrow-the soft tissue inside of bonesred marrow makes blood cellsyellow marrow is fat cells

Joints-where two bones come together

Tendons-connect muscle to bone

Ligaments-connect bones to other bones

Cartilage-material that is lighter and more flexible than bone, it makes a cushion between bones

Interesting facts about bones:

1. The smallest bones are in the ear, the largest bone is in your thigh (femur)

2. Cartilage decays faster than bone which is why skeletons have no ears or noses

3. The most frequently broken bone is the clavicle (collar bone)

6. The Nervous SystemPurpose of the nervous system is to control

and coordinate body functions, respond to external and internal stimuli

Brain-divided into areas that control different body functions

Spinal cord-dorsal, links the brain to the rest of the body

Motor nerves-carry message from brain to muscle

Sensory nerves-carry message from organ to brain

Nerve cell:

Dendrite-receives information

Cell body-contains nucleus and other cell organelles

Axon-tail that carries message to next cell

Neurotransmitters-chemicals that carry the message across the space between nerve cells

Interesting facts about the nervous system:1. Humans have 100 billion nerve cells in the

brain2. Nerve cells cannot be replaced if damaged

7. The Endocrine SystemPurpose of the endocrine system-deliver

chemical messages throughout the body

Gland-group of cells that makes and secretes a hormone

Hormone-chemical that gives instructions to cells

Hypothalamus-in the brain, it controls the pituitary

Pituitary-size of a pea, located below brain, called the master gland as it controls many other glands. It makes growth hormone and endorphins

                                                                                   

Thyroid-in the neck, makes two hormones that control metabolism (turning food into energy)

Adrenal-on top of kidneys, control water/salt balance, releases adrenaline for stress

                                                                                              

Ovaries-estrogen for female characteristics

Testes-testosterone for male characteristics

Interesting facts about the endocrine system:

1. A girl is born with over 60,000 eggs in her ovaries

2. It takes 72 days to make a sperm cell

8. The Lymphatic/Immune System

Purpose of the lymphatic system-filter blood of disease causing organisms and make antibodies

Lymph-milky fluid that contains WBC, proteins, fat

Nodes-over 100 small oval structures that filter out germs and toxins

                                                                                                    

                              

Spleen-large structure that produces WBC, filters out worn out RBC, recycles iron for new cells

Thymus-located under sternum, helps the defense cells mature

Interesting facts about the lymphatic system:

1. Tonsils are lymph nodes in the back of the mouth. If they are chronically infected they are often removed

2. There is a parasitic worm that can live in lymph vessels. It causes the fluid to back up resulting in elephantiasis

9. The Excretory System

Purpose of the excretory system: filter blood and remove toxic waste, maintain salt and water balance

Kidneys-blood enters, waste is removed, water is recycled

Ureters-tubes that carry urine from kidney to bladder

Bladder-elastic sac that stores urine until it can be eliminated

Urethra-tube that carries urine from the body

                                                                                          

   

Interesting facts about the excretory system:

1. Each kidney has 1 million filtering units

2. The ancient Romans used urine as bleach when they did their laundry