Emma-Nervous+System+Reading


 * p. 17 #2
 * p. 83 #7, 11
 * p. 245 #9
 * p. 271 #1, 2
 * p. 293 #1, 4

Homeostasis is the bodys internal environment that is contained within certain limits,in regard to temperature. Homeostasis is also involved in maintaining the body's temperature by shivering when it's cold and sweating when it's hot. Although homeostasis is able to somewhat maintain temperature within the body, it is important to note that our internal temperature is dependent on the external temperature and drastic temperatures can be deadly. Homeostasis would not occur if it werent for out body's ability to respond to stimuli. Also, the body is able to detect internal stimuli which brings the central nervous system into play.
 * 2: What is homeostasis and how is it maintained? Give some examples that show how systems work together to maintain homeostasis.

Integumentary system is defined as, " helps maintain body temperature and protects internal organs. Skin has "several accesory organs; hair, nails, sweat glands, and sebaceous glands. Skin also has many functions, it protects underlying tisues from physical trauma, pathogens invasion, and water loss; it also plays a key role in regulating body temperature, or homeostasis. #11:Why is homeostasis defined as the " relative constancy of the internal environment?" Does negative feedback or positive feedback tend to promote homeostasis? (78-81) The role of homeostasis is to keep the body at a relatively constant temperature. Negative feedback promotes homeostasis, it does so by being present when the output of the system dampens the original stimulus.
 * 7:Explain why the skin is sometimes referred to as he integumentary system.(71)

The muscular system helps maintain homeostasis in different ways. First, muscle contractions allow us to move and if our external environement is overheating our bodies then we have the option to move into shade, due to the muscular system. The muscular system also allows you to chew food which is then distributed to all the cells in the body that need nutrients. The muscular system is also reponsible for contractions of the cardiac muscle, the heart.
 * 1) 9 How does the muscular system help maintain homeostasis?

1.The nervous system receives sensory input--sensory receptors in the skin and other organs respond to external and internal stimuli by generating nerve impulses that travel by way of the Central Nervous System and the peripheral nervous system 2. The CNS performs integration--sums up the input it receives from all over the body 3. The CNS generates motor output--nerve impulses from the CNS go by way of the PNS to the muscles and glands.
 * 1:What are the three functions of the nervous system? (page 248)

-Sensory Neurons- take the nerve impulses(messages) from a sensory receptor to the CNS. -interneuron-lies entirely within the CNS. They can receive input from sensory neurons and also from other interneurons in the CNS. Therefore, they sum up all the nerve impulses reveived from these neuons before they communicate with motor neurons. -Motor Neuron- takes nerve impulses away form the CNS to an effector (muscle fiber or gland). -Effectors- carry out our responses to environmental changes, whether they are external or internal
 * 2:What are the functions performed by the three types of neurons? Describe the structure and functions of the three parts of a neuron.

exteroceptors are sensory receptors that detect stimuli from outside the body, such as those that result in taste, smell, vision hearing, and equilibrium. interoceptors receive stimuli from inside the body. For example, among interocepts, pressoreceptors respond to changes in blood pressure, osmoreceptors monitor the pH of the blood.
 * 1: Contrast extroceptors and interoceptors:

Sensitive to fine touch: Meissner corpuscles, Merkel Disks, root hair plexus sensitive to pressure: Pacinian Corpuscles and Ruffini endings Temperature: free nerve endings in the epidermis
 * 4:List the cutaneous receptors and the type of stimulus each responds to.