Chapter 50: Sensory and Motor Mechanisms

Question 1

sensory receptors

Answer 1

neurons or regulate neurons; different types respond to different stimuli

Question 2

chemoreceptors

Answer 2

bind molecules, initiate change in membrane potential

Question 3

mechanoreceptors

Answer 3

deformed or moved to sense pressure, stretch, motion, etc

Question 4

electromagnetic receptors

Answer 4

detect light, electricity, magnetism, etc.

Question 5

thermoreceptors

Answer 5

detect heat and cold

Question 6

nociceptors

Answer 6

detect ‘pain’ like extreme pressure, chemicals, etc.

Question 7

4 stages of getting a stimulus to the brain

Answer 7

receptions, transduction, transmission, perception

Question 8

reception

Answer 8

sensory cells detects stimulus

Question 9

transduction

Answer 9

conversion of stimulus to receptor potential; magnitude varies with intensity of stimulus

Question 10

transmission

Answer 10

strength of stimulus modulates frequency of action potential; integration/processing

Question 11

perception

Answer 11

central nervous system (brain) processing of input from sensory neurons

Question 12

modifications of transduction

Answer 12

amplification-strengthening of stimulus; adding energy
adaptation-becoming unresponsive to constant stimulation

Question 13

gustation

Answer 13

detection of tastants in solution by chemoreceptors; taste buds recognize sweet, sour, salty, bitter, and savory

Question 14

olfaction

Answer 14

smell; detection of odorants in air by chemoreceptors

Question 15

hearing and balance

Answer 15

based on mechanoreceptors and closely related

Question 16

conversion of waves in air to fluid

Answer 16

outer ear: tympanic membrane (eardrum) vibrates
middle ear: three tiny bones transmit vibrations
inner ear: cochlea receives vibrations

Question 17

vestibular canal

Answer 17

waves flow down vestibular canal, cause vibrations that stimulate hair cells

Question 18

volume

Answer 18

magnitude of the vibrations

Question 19

pitch

Answer 19

frequency of waves; basilar membrane has varying thickness, different parts vibrate in response to different pitches

Question 20

lateral line system

Answer 20

mechanoreceptors for detecting low frequency vibrations (like small hairs in ears of mammals)

Question 21

hearing in fish

Answer 21

no outer ears; vibrations pass from water, through body

Question 22

hearing in insects

Answer 22

hairs on their bodies that vibrate, tuned to specific frequencies

Question 23

statocysts

Answer 23

chamber surrounded by ciliated cells, statoliths move around as body moves to sense gravity

Question 24

balance

Answer 24

associated with ears; inner ear has utricle (horizontal) and saccule (vertical) chambers lined with hair cells and little stones (otoliths); tilting your head causes the stones to move

Question 25

semicircular canals

Answer 25

detect angular motion, oriented in 3 planes

Question 26

photoreceptors

Answer 26

cells that detect light

Question 27

ocelli

Answer 27

simple cup of photoreceptors; cup creates shadow to determine light direction

Question 28

single-lens eyes

Answer 28

functions kind of like a camera; single opening with a lens to focus light on a field of photoreceptors

Question 29

compound eyes

Answer 29

composed of many light detectors; each facet has own lens, responsible for a small part of the visual field

Question 30

vertebrate eye layers

Answer 30

sclera, choroid, retina

Question 31

outer sclera

Answer 31

white, protective layer made of collagen and elastic fiber

Question 32

middle choroid

Answer 32

vascular layer

Question 33

inner retina

Answer 33

layers of neurons and photoreceptors

Question 34

movement of light through eye

Answer 34

enters through cornea (transparent area of sclera) surrounded by iris, through pupil (actual hole for light) to lens (transparent protein that focuses light by changing shape)

Question 35

types of photoreceptors

Answer 35

rods, cones, and intrinsically photosensitive retinal ganglion cells (iPRGCs)

Question 36

rods

Answer 36

sensitive to light but not colors

Question 37

cones

Answer 37

distinguish colors, but not very light sensitive

Question 38

intrinsically photosensitive retinal ganglion cells (IPRGCs)

Answer 38

signal environmental light level to the central circadian clock and contribute to the pupil light reflex

Question 39

fovea

Answer 39

center of focus: 150,000 cones/mm^2

Question 40

rhodopsin

Answer 40

visual pigment in rods; in membrane of stacked disks in rod, shape changes with absorption of light. Leads to signal transduction that closes Na+ channels

Question 41

photopsins

Answer 41

visual pigment of cones; works similarly to rhodopsin

Question 42

transmission of vision to brain

Answer 42

photoreceptors interact with a variety of different neuron types that process the information from each receptor; ganglion cell axons transmit impulses to the brain

Question 43

vertebrate skeletal muscle

Answer 43

muscles attached to bones, responsible for locomotion; organized muscle, fiber, myosin

Question 44

muscle

Answer 44

bundle of fibers running parallel to bone

Question 45

fiber

Answer 45

single cell (multiple nuclei) with bundles of myofibrils

Question 46

myofibrils

Answer 46

composed of thin (actin) and thick (myosin) filaments

Question 47

sarcomere

Answer 47

basic contractile unit of myofibril; ends of actin fibers line up at ends (z lines), middle of myosin fibers lined up (m line)

Question 48

sliding-filament model

Answer 48

muscles contract by actin and myosin sliding past each other; head binds ATP, head hydrolyzes ATP to ADP and used energy to change shape, head binds to actin filament, head releases ADP but holds on to actin, binding new ATP causes head to release, cycle repeats

Question 49

sliding filament model cycle

Answer 49

head binds ATP, head hydrolyzes ATP to ADP and used energy to change shape, head binds to actin filament, head releases ADP but holds on to actin, binding new ATP causes head to release, cycle repeats

Question 50

contraction of muscle fibers

Answer 50

controlled by tropomyosin (coils around actin) and troponin complex (arranged along tropomyosin) and Ca2+ (binds troponin complex)

Question 51

action potential to myofibril contraction

Answer 51

1. With action potential, motor neuron releases acetylcholine, binds to receptors on muscle 2. Triggers action potential, transverse tubules carry action potential (AP) deep into muscle cell 3. AP causes sarcoplasmic reticulum (SR) to release Ca2+ 4. Troponin complex and tropomyosin move out of the way 5. Sarcomere contracts 6. When motor neuron stops firing, Ca2+ pumped back to SR 7. Troponin complex and tropomyosin move back in the way, fiber relaxes

Question 52

motor unit

Answer 52

all fibers controlled by one neuron, all contract together

Question 53

tetanus/tetanic contraction

Answer 53

rapid AP's lead to rapid twitches; can sum

Question 54

skeletal muscle

Answer 54

composed of multiple fiber types

Question 55

cardiac muscle

Answer 55

found only in the heart; striated, can generate own action potentials

Question 56

smooth muscle

Answer 56

in walls of hollow organs; not striated

Question 57

endoskeleton

Answer 57

muscles surround bone skeleton

Question 58

exoskeleton

Answer 58

muscle within skeleton

Question 59

antagonistic pairs

Answer 59

muscles work in antagonistic pairs; one contracts while the other relaxes

Question 60

hydrostatic skeleton

Answer 60

animals lack hard skeletons; body cavity filled with non-compressible fluid, contracting longitudinal muscles causes body to shorten, contracting circular muscles causes body to lengthen

Question 61

ball and socket joint

Answer 61

multiple planes of movement

Question 62

hinge joint

Answer 62

one plane of movement

Question 63

pivot joint

Answer 63

rotation

Question 64

osteoblasts

Answer 64

secrete bone matrix

Question 65

osteoclasts

Answer 65

resorb bone components