Human Body Systems 2 VI. Nervous; A. Function; Control of thought, senses, and all body systems. B. Regions; 1. Central Nervous System (CNS)- Includes the brain and spinal cord.

a. cerebrum- intelligence, language, memory, a. cerebrum- intelligence, language, memory, senses and of voluntary muscles b. cerebellum- controls balance and coordination c. brain stem- connects various parts of the brain, and controls involuntary muscles. d. spinal cord- connects the CNS to the PNS.

2. Peripheral Nervous System (PNS); All of the nervous system outside of the central nervous system.

C. Neurons; Nerve cells 1. cell body- main part of the cell, containing the nucleus 2. dendrite- receives nerve impulse and sends it to the cell body 3. axon- receives the impulse from the cell body and passes it to the next neuron. 4. synapse- the gap between the axon of one neuron and the dendrite of another neuron

D. Neuron Types; 1. sensory- sends nerve impulse from the peripheral nervous system (PNS) to the central nervous system (CNS). 2. motor- sends nerve impulses from the CNS to the PNS 3. interneuron- found in the brain and spinal cord. Processes incoming impulses and passes them to the motor neurons.

VII. Respiratory A. Function; Exchange of gases for cellular respiration. By diffusion, oxygen in the lungs diffuses into the blood stream, and carbon dioxide in the blood stream diffuses into the lungs. B. Organs 1. trachea- windpipe 2. bronchi- divides trachea so that air goes to each lung. 3. lungs- main organ of the system. Inhaling takes air into the body, exhaling pushes air out.

a. alveoli- air sacs one cell layer thick allow a. alveoli- air sacs one cell layer thick allow gases to diffuse into and out of the lungs.

VIII. Circulatory; A. Function; Transport of blood throughout the body. Part of the body’s immune system (white blood cells). B. Organs 1. Heart- made of cardiac muscle, pumping causes blood to circulate through the body. a. atria- the two upper chambers of the heart b. ventricles- the two lower chambers of the heart 2. arteries- vessels that take blood away from the heart. 3. veins- vessels that take blood toward the heart. Contain valves to keep the blood moving in the right direction.

4. capillaries- smallest blood vessels (microscopic). Only one cell layer thick, and they are so thin they only let one blood cell pass through at a time. Capillaries allow the diffusion of gases into and out of the circulatory system. They are the transition vessels between veins and arteries

C. Blood tissue; 1. plasma- 55% of volume of blood. Fluid part of blood. 2. white blood cells - 1% volume. Work with immune system to fight disease. 3. red blood cells- 44% carry oxygen to cells, and some carbon dioxide away from cells. a. hemoglobin- protein that bonds oxygen and some carbon dioxide to red blood cells. 4. platelets- cell fragments that aid in clotting the blood.

IX. Urinary; A. Function; Removal of waste from the blood stream. B. Organs 1. Kidneys- Organs that contain nephrons a. nephrons- small tubes that filter impurities from the blood 2. ureters- tubes that transport urine from the kidneys to the bladder 3. bladder- bag for holding urine 4. urethra- tube that empties the bladder

X. Reproductive A. Function; Formation of gametes, fertilization, and development of a new person. B. Organs 1. Male- a. testes- form the sperm b. epididymis - tube in which sperm mature c. seminal vesicles- glands at the base of urinary bladder that secrete mucous like fluid

d. prostate gland- donut shaped gland. below. bladder d. prostate gland- donut shaped gland below bladder. Secretes fluid to help sperm move and survive. e. bulbourethral glands- beneath prostrate. Produces fluid that neutralizes acidic environment f. semen- sperm and all of the other reproductive fluids

2. Female- a. ovaries- form the eggs b. oviduct- tube to transport egg from ovary to uterus c. uterus- during pregnancy, this is where the fetus develops d. cervix- opening into the vagina from the uterus

X. Lymphatic System; A. Funtions 1. Immunity; filters out pathogens, forms acquired immune response, uses white blood cells to destroy or trap pathogens 2. Maintains homeostasis of body fluids; Returns fluids to the blood stream once they have leaked into the body tissues. B. Organs and Cells; tissue fluid that enters the lymph vessels is called lymph. 1. Thymus gland; located above the heart. Converts white blood cells into pathogen fighting cells.

a. lymphocytes- found in the tonsils and lymph nodes b. T-Cells – work with B-cells to form antibodies. 2. lymph nodes; mass of tissue containing lymphocytes that functions to filter out pathogens. 3. spleen; stores lymphocytes, filters and destroys pathogens, but does this by filtering blood instead of lymph.

4. tonsils; located at the back of the throat, work 4. tonsils; located at the back of the throat, work the way lymph nodes do 5. Lymph veins; flow toward the heart, and return lymph to the blood stream at the lymphatic and thoracic ducts. * There are no lymph arteries