Chapter 31

Question 1

Sensory system

Answer 1

Portion of nervous system. In vertebrates, consists of sensory neurons, nerves, and brain regions for information processing.

Question 2

Stimulus

Answer 2

Form of energy that activates receptor endings of a sensory neuron

Question 3

Somatic sensations

Answer 3

Basically the 5 senses, except not. Taste, smell, hearing, vision, and balance. Responses to receptors near body surface and in skeletal muscle, joints, and walls of soft internal organs.

Question 4

5 classes of sensory receptors

Answer 4

Mechanoreceptors, pain receptors, thermoreceptors, chemoreceptors, osmoreceptors, and photoreceptors

Question 5

Mechanoreceptors

Answer 5

Detect mechanical energy (eg change in pressure, position, acceleration). Found in ears.

Question 6

Pain receptors

Answer 6

Detect tissue damage

Question 7

Thermoreceptors

Answer 7

Detect temperature change

Question 8

Chemoreceptors

Answer 8

Detect chemical energy of specific substances dissolved in the fluid surrounding them. Found in noses and tongue.

Question 9

Osmoreceptors

Answer 9

Detect change in concentration of solutes in a body fluid (eg blood)

Question 10

Photoreceptors

Answer 10

Detect forms of light energy. Contain pigment molecules that can absorb photon energy, which can be converted to excitation energy in a sensory neuron.

Question 11

How does brain figure out stimulus location and intensity, if all action potentials are always the same size?

Answer 11

It figures out which nerve pathways have action potentials, the frequency of action potentials in the pathway, and the number of axons activated by the stimulus.

Question 12

Sensory adaptation

Answer 12

When sensory neurons stop firing despite continued stimulation. eg putting on a sock.

Question 13

Pain

Answer 13

Perception of tissue injury. Somatic pain comes from skin, skeletal muscle, joints, and tendons. Visceral pain comes from internal organs.

Question 14

Olfaction

Answer 14

Sense of smell. Chemoreceptors bind substances and dissolve them in fluid around them. Receptor axons lead into one of two olfactory bulbs, where neurons sort components of scent before signaling cerebrum.

Question 15

Olfactory receptors

Answer 15

Detect water soluble or easily vaporized chemicals. Humans have 5 million, bloodhounds have 200 million.

Question 16

Pheremones

Answer 16

Signaling molecules secreted by individual that changes social behavior of others in species.

Question 17

Vomeronasal organ

Answer 17

Responds to pheromones, located in nasal cavity. Cluster of sensory neurons.

Question 18

Taste receptors

Answer 18

Clusters of chemoreceptor and supporting cells in special epithelial papillae. Detect chemicals dissolved in fluid.

Question 19

5 tastes and what cause them

Answer 19

Sweet = Glucose and simple sugarsSour = AcidsSalty =NaCl and other saltsBitter = plant toxins, like alkaloidsUmami = Amino acids like clutamate

Question 20

Organs of equilibrium

Answer 20

Part of sensory systems that monitor body’s poisitions and motions (eg ears with their vestibular apparatus)

Question 21

Vestibular apparatus

Answer 21

3 semicircular canals and 2 sacs (saccule and utricle). Have hair cells that react when fluid in ear deforms cilia on hair cells. Dynamic equilibrium senses any angular movement and rotation of head. Static equilibruim in saccule and utricle help monitor head’s position and how fast head is moving in a straight line. Helps with posture and keeping the head upright.

Question 22

Middle ear

Answer 22

Amplifies and transmits air waves to the inner ear. Auditory canal leads to eardrum, which vibrates from pressure waves. Behind is air filled cavity with hammer, anvil, and stirrup, which transmits force from eardrum to oval window. 9b on pg 518.

Question 23

Inner ear

Answer 23

Has cochlea, which is a pea sized, fluid-filled structure coiled like a snail shell. Transduction of sound waves into action potentials.

Question 24

Lens

Answer 24

Transparent body that bends all light rays from any point on visual field onto photoreceptors packed in retina.

Question 25

Outer layer of eyeball wall

Answer 25

Sclera - protects eyeballCornea-focuses light

Question 26

Middle layer

Answer 26

Pupil - entrance for lightIris - adjusts diameter of pupilCiliary body - Muscles control lens shape. Fine fibers hold lens in placeChoroid - Blood vessels give nutrition to wall cells. Pigments stop light from scatteringStart of optic nerve located here.

Question 27

Inner layer

Answer 27

Retina - absorbs and transduces light energy

Question 28

Interior of eyeball

Answer 28

Lens, aqueous humor (Transmits light, maintains fluid pressure), vitreous body (Transmits light, supports lens and eyeball)

Question 29

2 types of photoreceptors in pigmented epithelium behind retina

Answer 29

Rod cells - Detect dim light. Respond to changes in light intensity and the start of coarse perception of motion. Visual pigment is rhodpsin. Absorption of photon causes rod to change shape, starting reaction.Cone cells - detect bright light and is the start of sharp daytime vision and color perception. Three types, each with a different pigment. One pigment best for absorbing red light, another blue, and the last green.

Question 30

Signal processing for vision

Answer 30

Starts in retina, where rods and cones communicate with layers of neurons. Signal converge on bipolar cells, which go to ganglion cells. Ganglion cells axons bundle into an optic nerve to the optic chiasm in the brain. Information from right visual field sent to left hemisphere of brain, and vice versa. Each optic nerve ends in brain center which processes signals, then to visual cortex.