Human Body Systems

I. Integumentary; A. Main Functions; 1. homeostasis- animal’s regulation of internal environment to help them maintain survival conditions a. hot temps – blood vessels dilate and body sweats b. cold temps- blood vessels constrict directing the blood to the brain and other vital organs.

2. protective barrier against invasive 2. protective barrier against invasive infectious organisms and protection for the body’s internal organs. 3. receptor for the sense of touch- feels pain, pressure, heat, cold B. Organs; 1. Major organ is the skin (largest organ of the body). It is composed of; a. epidermis- outermost layer composed of dead cells and mitotic cells.

b. dermis- under the epidermis,. contains blood vessels and b. dermis- under the epidermis, contains blood vessels and nerve endings. Also location of sweat glands. c. subcutaneous- below the dermis, is composed of fat and connective tissue. 2. other organs consist of hair, nails and sweat glands

On average, a human will shed and regrow outer skin cells about every 27 days. We shed about 600,000 particles of skin every hour. There are as many hairs per square inch on human body, as a chimpanzee. Human hair is generally thinner and/ or lighter in color than chimpanzee hair, so it is less noticeable.

II. Skeletal; the adult human body has 206 bones. Axial (skull, spine and ribs) and appendicular (all other appendages) A. Main Functions; 1. support for the body 2. protection for internal organs 3. production of blood cells 4. storage of minerals B. Organs; 1. compact bone- solid bone for support and protection. 2. spongy bone- site of marrow production

3. marrow- *red marrow- makes blood cells *yellow marrow- mostly fat 4. cartilage- hard flexible material found in the nose, outer ears and between joints. C. Movable Joints; 1. hinge- found in the fingers, elbows and knees

2. pivot- Allows the lower arm to turn. Allows the head to turn 3. ball and socket- found in the hips and shoulders 4. gliding- found in the wrists and ankles D. Fixed Joints; Joints that fuse together and do not allow movement. These joints include the bones in the skull and pelvis.

The hardest bone in the human body is the jawbone. Twenty five percent of a person’s bones are in their feet. There are 26 bones in each foot. About 30% of a baby’s bones are not fused together at birth. They are born with 300 bones.

III. Muscular; muscles work by alternately contracting and relaxing. Muscles do not work by pushing. A. Main Function; is movement B. Organs/ Cell types; voluntary muscle is consciously controlled, involuntary muscle is not. 1. cardiac muscle- found only in the heart. Involuntary

2. smooth muscle- muscles of the body’s organs. Involuntary a. peristalsis is the muscular contraction that takes food to the stomach from the esophagus. 3. skeletal muscle- muscle that is attached to the skeleton that is used for voluntary movement.

It takes approximately 200 muscles to take a step. The strongest muscle in the human body is,,,,, the tongue. After an injury, the tongue is also the fastest repairing organ,.

IV. Digestive; continuous tube A. Main Function; Break down and absorption of food B. Organs; 1. mouth- mechanical chewing and chemical saliva * amylase is an enzyme in saliva that breaks starches down into simple sugars. 2. esophagus- food tube, uses peristalsis 3. stomach- gastric juices and acid chemically break down food *HCl in the stomach denatures proteins (causes them to unfold) *pepsin- enzyme that breaks down proteins

4. small intestine- small diameter, but very long. a. duodenum the first part of the small intestine. *Enzymes from the pancreas and bile from the gall bladder chemically and mechanically break down partially digested food. b. Villi - (finger-like projections) absorb digested food and move it into the bloodstream.

5. colon (large intestine)- Water and salts are 5. colon (large intestine)- Water and salts are absorbed making the indigestible material more solid 6. rectum/ anus- removes waste in the form of feces

V. Endocrine; Works with the nervous system V. Endocrine; Works with the nervous system. Hormones are chemicals that travel through the blood stream. A. Main Function; Secretion of hormones to control the functions of the other body systems. B. Glands; 1. hypothalamus- connects brain to the endocrine system and controls the pituitary gland

2. pituitary – controls the release of hormones 2. pituitary – controls the release of hormones by the other endocrine glands. 3. thyroid- controls growth, development and metabolism 4. parathyroid- regulates the use of minerals 5. adrenal- production of adrenalin for stress producing situations. 6. testes and ovaries- produce sexual hormones.