Bio 119: Fish Nervous System

Front 1

meninges

Back 1

connective tissue covering brain

Front 2

cerebrospinal fluid

Back 2

found between meninges and brain

Front 3

prosencephalon

Back 3

forebrain; region of all olfactory sense

Front 4

forebrain: telencephalon

Back 4

cerebrum; made up of the olfactory bulbs, olfactory lobes, and olfactory epithelium

Front 5

forebrain: diencephalon

Back 5

posterior part of forebrain; made up of pineal gland, hypothalamus, saccus vasculosus

Front 6

pineal gland

Back 6

part of diencephalon; also called epiphysis; @ roof of diencephalon; light-sensitive tissue

Front 7

hypothalamus

Back 7

part of diencephalon; @ floor; collection of nerve bodies; site of integration; found just outside of pituitary

Front 8

pituitary gland

Back 8

protrusion of hypothalamus; endocrine; releases hormones

Front 9

saccus vasculosus

Back 9

part of diencephalon; posterior to hypothalamus; highly vascularized evagination of third ventricle; filled CSF

inner part of evagination lined with ciliated cells projecting into CSF so may be able to detect change in fluid pressure which happens during diving

Front 10

mesencephalon

Back 10

midbrain; site of visual sense; made up of optic lobes and

optic tectum (unknown fxn; @roof)

and torus semicircularis

Front 11

midbrain: torus semicircularis

Back 11

@ floor of midbrain; receives somatotopically ordered electrosensory input from the medulla and caudal lobe of the cerebellum, and input from optic tectum

Front 12

rhombencephalon

Back 12

hindbrain; made up of the metencephalon and myelencephalon

Front 13

hindbrain: metencephalon

Back 13

cerebellum; coordinates neural info related to motion and balance; consists of the valvula cerebelli and corpus cerebelli;

where eminentiae granulares are found

Front 14

eminentiae granulares

Back 14

lateral swellings; larger in fishes that are able to produce electricity

Front 15

hindbrain: myelencephalon

Back 15

consists of the medulla oblongata and Mauthner cells

Front 16

Cranial Nerve 0

Back 16

11th CN; found at the anterior part of fish brain and closely associated with olfactory nerves;

cross reacted with Gonadotropic Releasing Factor so may pick up odor related to reproductive processes

Front 17

Spinal Cord

Back 17

central canal continuous with 2nd and 3rd ventricle of brain; has CSF; typical organization

Front 18

Chemoreception

Back 18

serves immediate physiological processes; for intraspecific communication;

remember! stimuli very prevalent in universal solvent, water

Front 19

2 major components of chemoreception

Back 19

sense of olfaction and sense of taste

Front 20

sense of olfaction

Back 20

detects distant odors; mediated by CN ; situated in the olfactory pit; blind sac unlike in higher vertrates

Front 21

soo: olfactory pits

Back 21

usually found in pairs; consists of the opening nares

Front 22

soo: monorhinic

Back 22

in agnathans; one olfactory pit

Front 23

soo: nostril divisons

Back 23

modified nostrils; may be divided into incurrent and excurrent siphons

Front 24

soo: incurrent nares (some)

Back 24

modified nostrils; funnel shaped for iso-osmotic ventilation

Front 25

soo: isoosmotic ventiltion

Back 25

modified nostrils; occurs in funnel shaped incurrent nares; water being lead into opening whenever fish moves

Front 26

soo: ciliated cells in nares

Back 26

modified nostrils; produces water current for ventilation in nares

Front 27

soo: cycloosmotic irrigation

Back 27

modified nostrils; deformation of accessory sac; every time mouth opens/closes, volume of accessory sac expands/compresses

Front 28

soo: olfactory rosette

Back 28

flower-shaped epithelia lining olfactory chamber

Front 29

soo: raphe

Back 29

longitudinal ridge; eventually runs along axis of nostrils to form the rosette

Front 30

soo: lamellae

Back 30

folds that arise from floor of olfactory chamber; increase surface area

Front 31

soo: olfactory chamber

Back 31

may contain sensory or non-sensory epithelial cells, ciliated or non-ciliated

continuously sloughed off and replenished by basal cells (?)

Front 32

soo: non-sensory epithelial cells

Back 32

goblet cells; for production of mucus to trap odor by a protein *

Front 33

soo: sensory epithelial cells

Back 33

usually concentrated a raphe; may be ciliated or microvillous; bipolar;

Front 34

soo: bipolar neurons

Back 34

have long axons projecting into serosal membrane and form olfactory tracts

Front 35

soo: excitable cells

Back 35

unstable and easily depolarized

Front 36

soo: sensitivity threshold

Back 36

very low; 10^-13 molar quantities so minute sources like amino acids can be detected

Front 37

soo: amino acids, bioacids, metabolites

Back 37

serve as food/ social cues

Front 38

soo: lateral olfactory nerve tracts

Back 38

found at outer sides of fibers

Front 39

soo: medial olfactory nerve tracts

Back 39

found at inner sides of fibers

Front 40

soo: spatial transmission

Back 40

olfactory information detected by olfactory epithelium (ex. food odor exclusively transmitted by lateral nerve tracts; reproductive cues exclusively transmitted by medial nerve tracts)

Front 41

soo: electroolfactogram (EOG)

Back 41

produced by change in membrane potential when electrical probe is inserted to olfactory nerve tracts

Front 42

sense of gustation

Back 42

exclusively related to food odor detection; relayed by several CNs (7, 9, 10); may be microvillous or ciliated; found almost everywhere;

Front 43

sog: sensitivity threshold

Back 43

relatively higher; can only detect micromolar quantities (10^-5 mq)

Front 44

mechanoreception

Back 44

has 2 major components: inner ear and lateralis of lateral line

Front 45

inner ear

Back 45

part of mechanoreception for detecting sound and balance; called membranous cavity/labyrinth; has distinct connection to body wall by an opening (endolymphatic duct) in sharks; has 2 subdivisions

Front 46

lateralis of lateral lobe

Back 46

part of mechanoreception for detecting water movement

Front 47

ie: endolymphatic duct

Back 47

found only in sharks; connects inner ear to body wall; filled with gel-like fluids

Front 48

ie: pars superior

Back 48

1 sub of inner ear; for balance; consists of utriculus ampulla

Front 49

ps: ampulla

Back 49

contains cupula, i think

Front 50

ps: crista

Back 50

mound consisting of sensory ciliated cells on top

Front 51

ps: macula

Back 51

sensory ciliated cells on top of crista; encased by gel-like structure

Front 52

ps: cupula

Back 52

gelatinous ridge encasing macula

Front 53

otolith

Back 53

calcareous structure barely touching sensory epithelial cells so if fish moves, otolith then cilia move, sending electrical signals;

grows through accretion; can be used to estimate age of fish;

Front 54

neuromast organ

Back 54

basic structure of acoustico-lateralis system; consists of the ampulla, cupula, macula, crista

Front 55

ie: pars inferior

Back 55

1 sub of inner ear; for sound detection; consists of the sacculus ampulla and lagena ampulla

Front 56

otolith: sagitta

Back 56

largest otolith; found in sacculus

Front 57

otolith: lapillus

Back 57

otolith found in utriculus

Front 58

otolith: astericus

Back 58

otolith found in lagena

Front 59

otophysic fish

Back 59

has connection of swim bladder with inner ear through tiny bones of vertebra called Weberian ossicles or has auditory bullae

Front 60

Weberian ossicles

Back 60

would pick up mechanical vibration caused by water disturbance to air trapped in swim bladder, and send vibration to inner ear

for ostarophysic fishes

Front 61

auditory bullae

Back 61

filled with gas originating from anterior part of swim bladder where it is connected to; this part of SB is also covered by a thin membrane connected to inner ear;

water disturbance would lead to vibration @ bullae then drum-like vibration @ membrane then to inner ear

for clupeomorphs

Front 62

superficial neuromast organ

Back 62

would have no otolith and cilia would just be shaken. would be found on epidermis at lateral line system connected by lateral line canal filled with endolymphatic fluid; cilia not at equal length

Front 63

no: kinocilium

Back 63

longer cilia found at the superficial neuromast organ; movement would increase firing rate of generation of action potential, increasing sensation of movement

Front 64

no: stereocilium

Back 64

cilia of varying length found at neuromast organ

Front 65

lateral line system

Back 65

disconnected: tilapia

directed dorsally: bottom dweller

bottom: flying fish

curved above pectoral fin: to avoid continuous disturbance by movement of fin

Front 66

electrosensory system

Back 66

for detecting weak currents by electrosensory receptors usually at the anterior; for communication

to detect movement caused by current generated by changes in membrane potential due to muscle contraction

Front 67

pit organs

Back 67

part of electrosensory system; epidermal depressions filled with electroconductive gel; at the bottom of each are neuromast cells; may be found at pectoral fins

Front 68

2 types of electroreceptors

Back 68

ampullary type

tuberous type

Front 69

electroreceptor: ampullary type

Back 69

for cartilaginous fishes; consists of the ampulla of Lorenzini

Front 70

ampulla of Lorenzini

Back 70

found at pit organs of sharks; communicate through a long canal filled with electroconductive gel

Front 71

remember! chemoreception vs electrosensory

Back 71

chemoreception can be overriden by electrosensory system

Front 72

fun fact! hammerhead sharks

Back 72

have large amounts of electroreceptors on their snout which leads them to keep moving their heads for scanning; lateral extensions increase area

Front 73

electroreceptor: tuberous type

Back 73

absence of long canal; for bony fishes

Front 74

electrocytes

Back 74

specialized cells, modified muscle cells able to generate and electric force powerful enough to stun preys;

horizontally stacked and innervated

Front 75

Photoreception

Back 75

system that needs the electrogmagnetic wave energy, light

Front 76

light

Back 76

varies in wavelength and frequency

Front 77

short wavelength

Back 77

shades of blue

Front 78

long wavelength

Back 78

shades of red

Front 79

light attenuation

Back 79

reduction of intensity when light hits the water; divides ocean into several zones

Front 80

euphotic zone

Back 80

200-300 m; enough light for photosynthesis to occur

Front 81

disphotic zone

Back 81

200-1000 m; twilight zone; light can penetrate but not enough to sustain life

Front 82

aphotic zone

Back 82

greater than 1000m; absolutely no light and freezing cold

can have light but from bioluminesence

Front 83

factors that affect penetration of light

Back 83

biotic: planktons and nektons

abiotic: sediment, garbage, temporal movement of earth relative to the sun

Front 84

lens

Back 84

spherical; held dorsally by a ligament and ventrally by ventral retractor lental muscle; grows by accretion;

Front 85

lens focusing

Back 85

very sharp because of a gradient in rerative indices (at the middle of the lens is densely packed protein and as you move laterally, becomes less dense)

Front 86

ventral retractor lental muscle

Back 86

able to move lens forward or backward, varying the focal length

Front 87

vitreous humour

Back 87

hit by light after lens is hit

Front 88

retina

Back 88

tissue hit by light after vitreous humour; measures max light absorbance level to distinguish visual pigments;

composed of several cell layers:

pigment epithelial cell

photoreceptor cells

bipolar neurons

ganglionic cells

Front 89

retina cell layer: pigment epithelial cells

Back 89

filled with melanin granules; have very long extensions letting granules move up and down; then encounters photoreceptor cells

Front 90

retina cell layer: photoreceptor cells

Back 90

consists of 2 types: cone and rods; tend to synapse with bipolar neurons

Front 91

cone cells

Back 91

photoreceptor cells; for bright and colored light conditons; contractile

Front 92

rod cells

Back 92

photoreceptor cells; for dim light conditions; contractile

Front 93

retina cell layer: bipolar neurons

Back 93

synapse with nerve cells to form ganglionic cells

Front 94

retina cell layer: ganglionic cells

Back 94

formed by synapse of bipolar neurons with nerve cells

Front 95

fish eyes

Back 95

laterally placed for wide field of vision

Front 96

binocular vision

Back 96

used by fish for better estimation of distance and depth

Front 97

nictitating membrane

Back 97

eyelid-like, found in sharks and other fishes;

acts as a wiper! especially during feeding frenzies for them to see better

Front 98

adipose eyelid

Back 98

streamlines head of fish by reducing bulge of eyes caused by large lens that pushes out cornea

Front 99

pupillary flap

Back 99

membrane that overhangs eyes of bottom-dwelling fishes to protect their eyes from sediment and downwelling light

Front 100

Snell's Window

Back 100

a 97 degree angled cone formed when light gets bent as it hits the water, allowing fishes to see from horizon to horizon

Front 101

eyeshine

Back 101

occurs in fish due their tapetum lucidum

Front 102

tapetum lucidum

Back 102

found between retina and sclera; made up of guanine crystals that are iridescent;

reflects light back to retina to see things better in dim waters

disadvantage: makes the fish more visible to predators

Front 103

rhodopsin

Back 103

dominant pigment found in rods; protein complex made up of protein, opsin

Front 104

rhodopsin opsin

Back 104

complexed with a chromatophore compund that may be derived from Vitamin A1

Front 105

porphyropsin

Back 105

dominant pigment found in cones; protein complex made up of the protein, opsin

Front 106

porphyropsin opsin

Back 106

complexed with a chromatophore compound that may be derived from Vitamin A2

Front 107

retina: deep-water fishes

Back 107

fishes with rods with visual pigments of low maximum light absorbance level

Front 108

retina: shallow-water fishes

Back 108

fishes with cones with visual pigments of high maximum light absorbance level

Front 109

ontogenetic shift

Back 109

dominance of pigment cells shift to adapt to change in light conditions due to ontogeny

Front 110

seasonal variations

Back 110

variation in light intensity caused by change in seasons

Front 111

retino-motor movement/photomechanical movement of pigment and visual cells

Back 111

long processes of pigment cells interdigitate with rods and cones; melanin granules act accordingly depending on light conditions

Front 112

retino-motor movement under dim light conditions

Back 112

melanin granules retreat backwards --> rods move toward incident light --> cones move toward direction of melanin granules

Front 113

retino-motor movement under bright light conditions

Back 113

melanin granules shield rods, which move backwards; cones move toward direction of incident light

Front 114

crepuscular period

Back 114

twilight; abundance of both rods and cones

Front 115

visual adaptation: colored cornea

Back 115

ability to reduce or enhance amount of light going to retina

Front 116

visual adaptation: photophores

Back 116

light-emitting tissue to make their presence known; result of cells that are able to produce bioluminescence or by symbiotic bacteria

Front 117

visual adaptation: "four-eyed" fish, <i>Anableps</i>

Back 117

has oval-shaped lens for air-water vision: long axis oriented downwards, short axis upwards

*sharper image from underwater due to long focal length caused by long axis

Front 118

Anableps: air water vision mechanism

Back 118

has iris flap, a membrane that divides pupil, which allows light from air and water to water

ventral retina receives light from above

dorsal retina receives light from below

Front 119

visual adaptation: tubular eyes

Back 119

for fishes in deep waters where there is very low intensity of light; pointed upward;

eye organ is elongated; presence of accessory retina so any light that arises from an angle may hit the lens and be detected by accessory retina

Front 120

visual adaptation: extraoccular sensory organ

Back 120

also the epiphysis/pineal gland, which is why frontal bone is thin, to let light pass

as endocrine: secretes melatonin which increases at nighttime