Nervous and Sensory Systems

Question 1

What is a nerve net?

Answer 1

(in invertebrates such as coelenterates and flatworms) a diffuse network of neurons that conducts impulses in all directions from a point of stimulus.

Question 2

Describe the basic nervous system in vertebrates

Answer 2

CNS consists of the brain and spinal cord and the PNS transmits sensory and motor signals between the CNS and the rest of the body.

Question 3

The simplest circuits in the vertebrate nervous system control ____ responses, in which sensory _____ is linked to motor ______ without involvement of the brain.

Answer 3

reflex, input, output

Question 4

What carries sensory signals to the CNS?

Answer 4

Afferent neurons

Question 5

What are efferent neurons?

Answer 5

Neurons that carry signals to skeletal muscles, or the autonomic nervous system (which regulates smooth and cardiac muscles).

Question 6

What is the difference between sympathetic and parasympathetic divisions of the autonomic nervous system?

Answer 6

The autonomic nervous system functions to regulate the body’s unconscious actions. The sympathetic nervous system’s primary process is to stimulate the body’s fight-or-flight response. It is, however, constantly active at a basic level to maintain homeostasis.

The parasympathetic system is responsible for stimulation of “rest-and-digest” or “feed and breed”[3] activities that occur when the body is at rest, especially after eating, including sexual arousal, salivation, lacrimation (tears), urination, digestion and defecation.

Question 7

What is the enteric division?

Answer 7

The division of the autonomic nervous system that controls the activity of many digestive organs.

Question 8

Describe the vertebrate brain.

Answer 8

Cerebrum: 2 hemispheres, cortical gray matter on top of white matter and basal nuclei (which are important in planning and learning movements)

Pons and medulla oblongata: relay stations for information traveling between PNS and cerebrum

Pons, brainstem, and parts of forebrain control sleep and arousal.

Cerebellum: coordinates motor, perceptual and cognitive functions.

Thalamus: main center through which sensory information passes to the cerebrum

Hypothalamus: regulates homeostatis and basic survival behaviors

Suprachiasmatic nucleus: acts as a pacemaker for circadian rhythms

Amygdala: key role in recognizing and recalling a number of emotions

Question 9

Each side of the ________ has four lobes that contain primary sensory areas and association areas.

Answer 9

Cerebral cortex

Question 10

Describe how the cerebral cortex controls voluntary movement and cognitive functions.

Answer 10

Specific types of sensory input enter the primary sensory areas. Association areas integrate information from different sensory areas. Broca’s area and Wernicke’s area are essential for generating and understanding language.

Question 11

What is the region of the brain in birds that contains clustered nuclei that carry out functions similar to the cerebral cortex in mammals?

Answer 11

Pallium

Question 12

What is neural plasticity?

Answer 12

The reshaping of the nervous system through the loss and addition of synapses, or the strengthening or weakening of signaling at the synapses.

Question 13

What is a neurotransmitter?

Answer 13

A chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure

Question 14

What is the difference in mechanisms between short and long term memory?

Answer 14

Short term relies on temporary links in the hippocampus, long term memories replace the temporary links by connections within the cerebral cortex.

Question 15

What is the hippocampus?

Answer 15

The elongated ridges on the floor of each lateral ventricle of the brain, thought to be the center of emotion, memory, and the autonomic nervous system

Question 16

The detection of a stimulus precedes _______, the change in the membrane potential of a sensory receptor in response to a stimulus.

Answer 16

sensory transduction

Question 17

The resulting ________ controls transmission of action potentials to the CNS, where sensory information is integrated to generate a ________

Answer 17

receptor potential, perception

Question 18

What determines stimulus strength?

Answer 18

The frequency of action potentials in an axon and the number of axons activated.

Question 19

What determines the nature or quality of the stimulus?

Answer 19

The identity of the axon carrying the signal.

Question 20

What are mechanoreceptors?

Answer 20

A sense organ or cell that responds to mechanical stimuli such as touch or sound.

Question 21

What are electromagnetic receptors?

Answer 21

Receptors that detect electromagnetic radiation, or a kind of radiation including visible light, radio waves, gamma rays, and X-rays, in which electric and magnetic fields vary simultaneously

Question 22

What are thermoreceptors?

Answer 22

Signal surface and core temperatures of the body

Question 23

What is pain detected by?

Answer 23

A group of nocireceptors that respond to excess heat, pressure, or specific chemicals.

Question 24

What are chemoreceptors?

Answer 24

Detect either total or solute concentration or specific molecules. In smell (olfaction) and taste (gustation).

Question 25

How do invertebrates sense their orientation with respect to gravity?

Answer 25

Statocysts: onsisting of a sensory vesicle or cell containing statoliths (a calcareous particle).

Question 26

What forms the basis of hearing and balance in mammals?

Answer 26

Specialized hair cells.

Question 27

In mammals, the ______ transmits sound waves to the bones of the _____, which transmits the waves through the ________ to the fluid of the _______ of the inner ear.

Answer 27

ear drum, middle ear, oval window, cochlea

Question 28

Describe how pressure waves reach the brain.

Answer 28

The pressure waves in the fluid vibrate the basilar membrane, depolarizing hair cells and triggering action potentials that travel via the auditory nerve to the brain.

Question 29

What part aids in balance and equilibrium?

Answer 29

Receptors in the inner ear.

Question 30

What are some light detectors found in invertebrates?

Answer 30

Light sensitive eye spots (simple)
image-forming compound eyes
single lens eyes

Question 31

Describe the vertebrate eye

Answer 31

A single lens is used to focus light on photoreceptors in the retina. Rods and cones contain the pigment retinal, bonded to opsin (a protein).

Question 32

How does vision work in a vertebrate?

Answer 32

Absorption of light by retinal triggers a signal transudction pathway that hyperpolarizes the photoreceptors, causing them to release less neurotransmitter. Synapses transmit information from photoreceptors to cells that integrate information and convey it to the brain along axons that form the optic nerve.

Question 33

What is a nerve?

Answer 33

An enclosed, cable-like bundle of axons (nerve fibers, the long and slender projections of neurons) in the peripheral nervous system