exam #2

Question 1

what is homeostasis?

Answer 1

any process by which an organism tends to maintain a constant stable environment

Question 2

what are the different components of homeostasis control system?

Answer 2

variable, receptors, control center and effectors

variable: increase/decrease in physiological variable caused by internal or external change
receptors: detect change in the variable
control center: receive the information and determines whether action is required
effectors: produce compensatory change in the variable

Question 3

nervous system

Answer 3

• conscious: somatic nervous system
• unconscious: autonomic nervous system
• sensory: senses stimuli (change) in the body’s internal and external environment
• integrative: interpret stimuli
• motor: responds to stimuli by initiating muscle contraction or glandular secretions

Question 4

endocrine system

Answer 4

• uses hormones
• responses generally take longer to appear

Question 5

positive and negative feedback loops

Answer 5

negative: the response cancel pr counteract the original stimulus
positive: the response increase the original stimulus

Question 6

what division of the nervous system is responsible for a specific action?

Answer 6

nervous system = central nervous system (CNS) + peripheral nervous system (PNS)

CNS: brain + spinal cord
PNS: peripheral nerves

Question 7

afferent and efferent division

Answer 7

afferent division: carries the information about external (ex: temperature) or internal (ex: hunger) changes to the CNS (perceive stimuli)

efferent division: carries information from the CNS to effectors organ (ex: muscles, glands) (take action)

Question 8

what are the difference between the somatic and autonomic nervous system?

Answer 8

somatic nervous system: voluntary action. Nerve fibers of the motor neurons that supply the skeletal muscles.

autonomic nervous system: unvoluntary action. Nerve fibers that innervate smooth muscles, cardiac, muscles, and glands.

Question 9

what are the difference between the sympathetic and parasympathetic nervous system?

Answer 9

sympathetic: emergency (“fight-or-flight”), stressful situations. Prepares the body for strenuous physical activity.

parasympathetic nervous system: quiet, relaxed situations. Promotes body maintenance activities (ex: digestion, emptying the bladder).

Question 10

what are the two ways to classify neurons?

Answer 10

• by function
• by structure

Question 11

afferent neurons

Answer 11

• functional neurons
• also called sensory neurons
• their cell body is located inside the PNS, adjacent to the spinal cord
• their dendrites are located in the sensory organs
• generate action potentials in response to a particular type of stimulus (ex: touch)

action potentials are initiated at the receptor of the peripheral axon in response to a stimulus and are propagated along the axon(s) toward the spinal cord

Question 12

efferent neurons

Answer 12

• functional neurons
• also called motor neurons
• the cell body is inside the CNS, but most of the neuron is in the peripheral nervous system
• efferent axon travel out of the CNS to meet the muscle glands they innervate
• upper motor neurons start in the cerebral cortex and end in the spinal cord
• lower motor neurons start in the spinal cord and end in the muscles

Question 13

interneurons

Answer 13

• functional neurons
• also called association neurons
• are entirely located in the central nervous system
• about 99% of neurons belong in this category

two main role:
1. connect the afferent and efferent neurons and help integrate peripheral information to peripheral responses.
2. interconnections between interneurons themselves are responsible for the abstract phenomena associated with the mind (ex: thoughts, emotions, memory, creativity, intellect, motivation, etc)

Question 14

flaccid paralysis

Answer 14

• damaged to the lower motor neurons
• no movement
• no reflexes
• muscles limp and flaccid

Question 15

spastic paralysis

Answer 15

• damaged to upper motor neurons
• no voluntary reflexes
• increased muscle tone

Question 16

amyotrophic lateral sclerosis (ALS)

Answer 16

• motor neurons disease
• caused by deterioration and eventual death motor neurons (upper and lower), which stop sending messages to the muscles
• muscles gradually weaken, start to twitch and get smaller (atrophy)
  -eventually, the brain loses its ability to initiate and control voluntary movement

Question 17

multipolar neurons

Answer 17

• contain several dendrites and one axon
• usually intervene in thinking function
• most neurons in the brain and spinal cord belong to this type
• their cell bodies reside in the brain and spinal cord belond to this type
• can be efferent neurons or interneurons

Question 18

unipolar neurons

Answer 18

• axon and dendrites are fused together outside the cell body
• usually afferent neurons