Sensory Systems Flashcards

Question

Cones

Answer 1

Need brighter light Sensitive to various wavelengths Chromophore

Answer 2

4 cone types - tetrachromatic eg birds 2 cone types - dichromatic eg macaque 1 cone type - monochromatic - colour blind eg dolphin 3 cone types - trichromatic eg humans

Answer 3

High density of rods A ‘tapetum lucidum’ biological reflector system that is a common feature in the eyes of vertebrates. Functions to provide the light-sensitive retinal cells with a second opportunity for photon-photoreceptor stimulation, Enhances visual sensitivity at low light levels.

Answer 4

Vertebrate chemoreception consists of taste, olfaction and the vomeronasal (or Jacobson’s) organ Olfaction involves detection of an airborne (or waterborne) molecule into a specific receptor on the surface of an olfactory sensory cell Taste involves detection of a waterborne molecule into a specific receptor on the surface of a taste bud

Answer 5

Detects non-volatile chemical cues - Flehman’s response Linked to hypothalamus Used in the detection of pheromones (eg major urinary proteins in mice) Removal of the organ impairs sexual and social behaviour in rodents Snakes have a well developed paired Jacobson’s organs in the top of the buccal cavity. Molecules are collected by the wet tongue and then intorducted into the organ when the tongue is retracted

Answer 6

detects physical perturbations of the environment – the commonest are sound waves in the air (or water). (only mammals have true pinnae that focus sound waves down the ear canal). Sound waves going down the ear canal cause the ear drum to vibrate, which causes the ossicle bones to vibrate and transfer the sound waves to the cochlea. As the waves move through the fluid within the cochlea tiny hairs in the organ of Corti are disturbed, which generates nerve impulses which are perceived as sound.

Answer 7

The cochlea is filled with perilymph, - moves in response to the vibrations coming from the middle ear via the oval window As the fluid moves, the cochlear partition (basilar membrane and organ of Corti) moves Thousands of hair cells sense motion via their stereocilia, and convert that motion to electrical signals communicated via neurotransmitters to many thousands of nerve cells Hair cells in the organ of Corti are tuned to certain sound frequencies by way of their location in the cochlea

Answer 8

In fish there is an otilith which resists movement from sound waves whilst the endolymph surrounding it moves – this causes hairs to be moved and triggers a nerve response. Fish lack any outer ear structure as their whole body can absorb sound waves.

Answer 9

In amphibians there is a tympanic membrane on the side of the head (behind the eye) and this resonates and moves the columella – a bone that connects the tympanum to the otic capsule. Amphibians lack the semi-circular canals used in perceiving position as seen in mammals, crocodilians and birds.

Answer 10

Fish No bony structure to transmit vibrations No Tympanum No middle ear Otoliths vibrate Frogs, Reptiles, Birds Single columella Straight cochlea Mammals External pinna Three middle ear ossicles Coiled Cochlea (except monotremes)

Answer 11

System of mechanosensory organs found in aquatic vertebrates, mainly fish but most amphibian larvae and some fully aquatic adult amphibians posses mechanosensitive systems comparable to the lateral line Provides information about flow patterns around animal and nearby objects Used to detect movement and vibration Provides spatial awareness and the ability to navigate in space Plays an essential role in orientation, foraging behaviour, and shoaling The major unit of functionality of the lateral line is the neuromast Superficial on surface of skin – respond to water motion Within canals – respond to pressure variations and gradients in adjacent cells

Answer 12

Electroreception is used in electro-location (detecting objects) and for electro-communication Passive – Animal senses the weak bioelectric fields generated by other animals and uses it to locate them (e.g. foraging) Active – Animal senses its surrounding environment by generating electric fields and detecting distortions in these fields using electroreceptor organs (e.g. communication)

Answer 13

located in skin sensitive to electrical fields of low frequency - <0.1 – 25 Hz) Found in many types of fish

Answer 14

in depressions in epidermis and covered by epidermal cells Sensitive to electrical fields of high frequency – 50 Hz – 2 kHz) Found in species that produce their own electrical fields and most sensitive to the frequencies produced by the fish

Answer 15

Animal senses the weak bioelectric fields generated by other animals and uses it to locate them (e.g. foraging)

Answer 16

Animal senses its surrounding environment by generating electric fields and detecting distortions in these fields using electroreceptor organs (e.g. communication)

Answer 17

Electric field sensors of sharks Detect voltage differences Use electroreception to forage and possibly navigate

Answer 18

Use electroreception for mate attraction, territorial and agonisitic displays and mimicry Active electroreception has a range of about one body length

Answer 19

Allows an animal to detect a magnetic field to perceive direction, altitude or location. May underlie long-distance navigation in several animal species A method for animals to develop regional maps, e.g. of the Earth's magnetic field

Answer 20

Evolved independently in several different families of snakes It allows them to ‘see’ radiant heat at wavelengths between 5 and 30 μm Infrared light heats up parts of a thin membrane inside the pit organ, and TRPA1 proteins embedded on that membrane detect the temperature change Directional and sensitive Warm-blooded animals emit heat as infrared radiation Pit vipers can detect potential prey a meter away Accuracy enough to target vulnerable body parts of the prey Not only used for prey detection

Answer 21

So the simplest ‘eye’ would be some photoreceptors in the epidermis (a) that sense the absence or presence of light. If the photoreceptors are then located within a depression in the epidermis (b) then the animal can determine whether light hitting the photoreceptors can come from a particular direction. If the gap through which light can travel is reduced to a ‘pin-hole’ (c) then a basic image can be projected on to the photoreceptors and offers finer directional perception. If the hole is covered by a transparent surface (d) then the space can be filled with a transparent humour. If a lens then develops next to the hole (e) then there is an ability to focus an image on the photo receptors. The final stage (f) sees the development of an iris that can actively regulate the amount of light entering the eye.

Answer 22

ocean light penetration diminished quickly as you descend down the water column and the light wavelengths are filtered. Blue light extends furthest down and a full colour spectrum is only observable within a few metres of the surface.

Answer 23

A reflector system that provides retinal cells with a second change at light detection- increasing light sensitivity in low light level

Answer 24

Lower thresholds = greater sensitivity to sound

Answer 25

In air- more sensitive to low frequencies but less sensitive to high frequencies In water - more sensitive to all frequencies

Answer 26

No bony structure to transmit vibrations No tympanum No kiddle ear Otoliths vibrate

Answer 27

Single columella Straight cochlea

Answer 28

External Pinna Three middle ear ossicles Coiled cochlea (except monotremes)

Answer 29

Neuromast - - superficial on surface of skin = respond to water motion - within canals = respond to pressure vibrations and gradients in adjacent cells

Answer 30

Through eyes Via iron deposits in the beak Through ears

Answer 31

Light Colour of light

Answer 32

Sensory receptor cells convert stimulus energy into an electrical signal

Answer 33

Receptor binds to a neurotransmitter and opens an ion channel across a cell membrane Ligand-gated channels

Answer 34

Increase surface area Increase receptor number

Answer 35

Ionotropic Metabotropic

Answer 36

Receptor molecule acts like a neurotransmitter to activate a metabotropic cascade Receptor protein activates a G protein, which activates a second effector molecule in the cell that then affects ion permeability of the membrane

Answer 37

Rapid 10-50ms

Answer 38

Short latency action

Answer 39

Binding site and channel combined

Answer 40

Postsynaptic in general

Answer 41

Binding site not associated with channel G-protein or 2nd messenger involvement

Answer 42

Pre or postsynaptic

Answer 43

Some taste receptors Photoreceptors

Answer 44

Ionotropic

Answer 45

Transduction Encoding information about the stimulus

Answer 46

Even though all receptors use action potentials to encode stimuli the physical destination of the sensory axons deals with each different type of sensory receptor

Answer 47

Hollow shaft protrudes through exoskeleton and is attached to the end of a dendrite (nerve cell), which is supported by sheath and socket cells Move the bristle and the distal tip of the dendrite is stretched and deformed Deformation opens stretch-activated channels to allow cations (e.g. Na+ or K +) to move through the cell membrane generating a receptor potential across the dendrite’s plasmalemma If a threshold for membrane depolarisation is reached then an action potential is propagated

Answer 48

Small bristle movement does not cause enough depolarisation to reach a threshold – bristle movement is not detected More displacement cross the threshold and generates a train of action potentials Further deformation increases the frequency of the action potentials Transduction illustrated by the resting potential triggering an action potential Encoding illustrated by the frequency of action potentials

Answer 49

Lamellae form discs detached from the plasmalemma

Answer 50

Lamellae are continuous with the plasmalemma

Answer 51

In the dark Na+ channels are relatively open and there is a flow of ‘dark’ current across a relatively depolarised (-30mV) cell membrane in the outer part of the cell

Answer 52

Metabotropic transduction Rods contain rhodopsin- activated by light Activated rhodopsin stimulates transducin, a G-protein to activate a phosodiesterase enzyme Enzyme decreases cyclic guanosjne monophosphate (cGMP) concentration in the receptor cytoplasm Decrease in cGMP closes cyclic-nucleotide-gated channels for Na+ and reduces its influx into the cytoplasm

Answer 53

Hyperpolarisation Causes ion channels to close reducing the dark current

Answer 54

long, thin cell surrounded with plasmalemma and Schwann Cells (neurolemmocyte) and a Myelin Sheath

Answer 55

Sodium (Na+) and potassium (K+) ions continually diffuse across the plasmalemma Cl- ions and large negatively charged molecules cannot cross the plasmalemma Na+ and K+ concentrations on each side of the plasmalemma remain constant because sodium-potassium ATPase actively moves 3x Na+ out and 2x K+ in to the cytoplasm Produces a resting potential of –70mV

Answer 56

A neuron transmits a signal as an action potential in response to a stimulus The stimulus must of a sufficient size to cross a threshold that triggers the localised movement of ions across the plasmalemma The threshold stimulus increases permeability to Na+ ions which all rush into the cytoplasm and neutralises the resting potential, i.e. –70 mV → 0 mV = depolarisation The influx of Na+ ions temporarily confer a positive charge to the cytoplasm

Answer 57

Almost immediately voltage-gated Na+ channels close and voltage-gated K+ channels open and K+ ions leave the cytoplasm to build up a positive change again This sequence of events triggers the same molecular changes in adjacent areas of the plasmalemma and the action potential moves along the axon

Answer 58

After the action potential has moved on the membrane becomes hyperpolarised (more than –70mV) because of uncontrolled movement of K+ Sodium-potassium ATPase restores the resting potential During hyperpolarisation the membrane is insensitive to triggering another action potential This whole process takes ~ 3 milliseconds

Answer 59

exceeding the stimulus threshold does not increase the size of the action potential

Answer 60

increased by increasing axon diameter - most vertebrate axons < 10μm Some fish and amphibians have unmyelinated axons ~ 50μm (involved in rapid escapes) Myelination increases transmission by Saltatory conduction from node of Ranviers

Answer 61

1 mm wide and conduct an action potential at 36 m per second

Answer 62

nuclei” in CNS and “ganglia” in PNS

Answer 63

Axosecretory Axoaxonic Axodendritic Axoextracellular Axosomatic Axosynaptic

Answer 64

Axon terminal secretes directly into bloodstream

Answer 65

between two neurons Positively charged ions from the presynaptic end bulb directly depolarise the adjacent neuron

Answer 66

between neuron and a range of cell types Requires chemical agent called a neurotransmitter (e.g. acetylcholine or norepinephrine) to diffuse across the synaptic cleft

Answer 67

An arriving action potential stimulates the free diffusion of calcium ions into the presynaptic terminal Increased calcium ion concentration stimulates the merging of vesicles containing neurotransmitter molecules with the plasmalemma The neurotransmitters are released into, and diffuse across, the synaptic cleft Binding of the neurotransmitter molecules to the post-synaptic plasmalemma triggers depolarisation of the post-synaptic cell to generate an action potential Neurotransmitter is quickly de-activated by the post-synaptic cell Failure to deactivate would lead to continual stimulation of the cell

Answer 68

Interconnected neurons that form complex 2D nerve nets

Answer 69

Entire nervous system is comprised of 2 nets

Answer 70

One net lies at the base of the epidermis and the other at the base of the gastrodermis Neurons bridge the mesoglea Nerve impulses can move in any direction though the nets Diffusion conduction means that a stimulus at one point on the net radiates outwards like ripples on a pond No central control for coordinated responses

Answer 71

In swimming medusa, first indications of coordinated control are seen as nerve rings and ganglia are found around the margin of the bell Associated with sensory organs – e.g. ocelli, and the swimming musculature Ganglia are concentrations of neurons that serve as simple integration centres. Each ganglion is associated with a sensory organ and can generate motor output Greatest output from ganglia controls muscular activity Contraction of the musculature must be simultaneous so neurons in the nerve ring couple with muscle cells electrically with gap junctions

Answer 72

Intraepithelial nervous system Brain is collar-like and circumpharyngeal nerve ring 2 longitudinal nerve cords

Answer 73

Anterior brain consisting of 2 dorsal suprapharyngeal ganglia 2 ventral longitudinal nerve cords and paired segmental ganglia

Answer 74

Dorsal supra-oesophageal ganglia (brain`0 in the head with 2 connectives that circle the gut linking to 2 ventral longitudinal nerve cords Paired segmental ganglia with sensory and motor neurons Brain has 3 parts = protocerebrum, deutocerebrum and triocerebrum

Answer 75

Highly cephalised central nervous system All segmental ganglia have coalesced in the supra-oesophageal and sub-oesophageal ganglia 2 abdominal nerves extend longitudinally along the body

Answer 76

Brain and 2 large, longitudinal nerve cords Brain-ring of four anterior ganglia wrapped around the anterior alimentary tract Trend towards Cephalisation and fusion of the ganglia into a brain-liege structure Twisted configuration

Answer 77

CNS is highly cephalised, strongly concentrated and bilaterally symmetrical, enclosed in a cartilaginous cranium Supra-oesophageal part associated with sensory function Sub-oesophageal part associated with motor function Each appendage has a brachial nerve

Answer 78

Squid have giant axons – 1 mm in diameter, which allow for rapid transmission of action potentials Diameter of axons depend on length – short ones are narrow – allows for coordinated motor responses because action potentials all arrive at the same time

Answer 79

Radial symmetry- - posses nerve ring around the gut and 5 radial nerves (1 per ambulacra) 2 connected neural nets - sensory ectoneural = epidermis Motor hyponeural = coelomic lining

Answer 80

Neural nets increasingly integrated with a localised central nervous system with different sensory and motor networks Segmented ganglia Increasing coalescence of nerve tissue associated with the head and often ringing the anterior gut linked to ventral longitudinal nerve cords Nerve rings that coordinate responses to stimuli Generalised nerve nets

Answer 81

Rudimentary hollow brain Dorsal hollow nerve cord almost to the end of the tail Segmental sensory nerves Anterior neuropore that contain cilia that maintain a flow of water over and into the pore Brain no longer wrapped around the anterior part of the alimentary tract

Answer 82

Visceral Somatic

Answer 83

Somatic nervous system Autonomic - sympathetic, parasympathetic and enteric

Answer 84

During relaxation Nerves arise from the brain and sacral region of spinal cord Long efferent nerve fibres that synapse with ganglia in vicinity of organs and short efferent neurons that extend from the ganglia to the organs Stimulates salivary gland secretions, contracts pupils and relaxes sphincter muscles

Answer 85

division functions during “fight or flight” response Nerve fibres originate from the thoracic and lumbar regions of spinal cord to ganglia near the spine and long efferent neurons that extend to the organs Inhibits salivary gland secretions, dilates pupils and tightens sphincter muscles

Answer 86

Networks of neurons in the pancreas, gall bladder and digestive tract that control gut function Normally regulated by the sympathetic and parasympathetic systems

Answer 87

Nervous tissue is derived from ectoderm (outer cell layers) All vertebrates have a mesodermal notochord during development – forms basis for vertebral column Associated with a dorsal neural tube created by folding of ectoderm tissues

Answer 88

Dura matter – tough fibrous Arachoid – delicate Pia mater – contains small blood vessels that nourish the tissue

Answer 89

Central neural canal filled with cerebrospinal fluid Composed of grey and white matter Spinal nerves – number depends on degree of segmentation

Answer 90

Cell bodies and dendrites (associated with reflex connections)

Answer 91

Grey matter

Answer 92

Axons surrounded by myelin sheaths

Answer 93

No myelinated axons (no white matter) Shape helps facilitate diffusion of nutrients and oxygen In spinal cord

Answer 94

The distribution of white and grey matter differs between the various vertebrate groups. The lamprey, being a very primitive fish, lacks any white matter. Sharks have dorsal and ventral horns of grey matter surrounded by white matter and a sheath. Amphibians have ventral and dorsal horns of grey matter – the latter extend to the edge of the spinal cord – within white matter. Reptiles have grey matter surrounded by white matter but in the spinal cords of mammals and birds the dorsal grey matter extends to the edge of the spinal cord.

Answer 95

During early development anterior neural tube expands by accumulation of cerebrospinal fluid to form different parts that become folded and lie on top of each other Brains have three main parts – forebrain (telencephalon and diencephalon), midbrain (mesencephalon) and hindbrain (rhombencephalon) each with different roles

Answer 96

Forebrain Cerebrum – two hemispheres and related to sensory and motor integration Expanded tissue and increased complexity reflects importance of the brain region Cerebral cortex – primary sensory and motor areas Other areas deal with processing visual or auditory perception

Answer 97

Forebrain Thalamus – relays sensory information to higher brain centres Hypothalamus – controls many bodily functions – body temperature, sexual drive, metabolism, hunger and thirst Pineal gland – controls bodily rhythms Fish – processes sensory information

Answer 98

Fish & amphibians – 10 pairs; Reptiles, birds and mammals – 12 pairs Sensory-only and mixed nerves – e.g. vagus has sensory neurons leading to the brain and motor neurons leading to the heart and visceral organs

Answer 99

Centre for coordinating responses to visual stimuli Evolution of mid brain – also coordinates touch and auditory processing

Answer 100

Medulla oblongata connects brain to spinal column – reflex centre for breathing, swallowing, cardiovascular function and gastric secretion Cerebellum – outgrowth of medulla oblongata and coordinates motor activity (posture, movement, spatial orientation) Pons connects forebrain cerebrum to cerebellum and is important in the regulation of breathing

Answer 101

Reflex centre for breathing, swallowing, cardiovascular function and gastric secretion

Answer 102

Coordinates motor activity (posture, movement, spatial orientation)

Answer 103

Regulation of breathing

Answer 104

Controls bodily rhythms Secretes melatonin

Answer 105

Controls bodily functions- body temperature, sexual drive, metabolism, hunger and thirst

Answer 106

Relays sensory information to higher brain centres

Answer 107

Proprioception Touch Temperature Pain

Answer 108

Olfaction Gustation

Answer 109

Olfactory epithelium Olfactory nerves - olfactory receptors Olfactory bulbs - glomeruli and mitral cells Rest of CNS Accessory olfactory bulb

Answer 110

Olfactory epithelia Olfactory nerves and receptors

Answer 111

Finding food Finding mates Mother and young bond Detecting predators

Answer 112

Air passes through the nares into the nasal cavity Pushed with turbulence over the olfactory epithelium Particles bind to olfactory receptors Transducer into signals via olfactory nerve to olfactory bulb Glomeruli activated Information passed via olfactory tract to a range of brain areas Decision are made - motor outputs

Answer 113

A mixture of molecules that is different from its surroundings and that trigger a sensation in the animal detecting it Defined by the nature and concentration of the odorants that are present in it Form a plume in air or carried by water

Answer 114

Protects from toxins/oathogens Helps some odorants bind Contains enzymes which degrade odours once bound

Answer 115

Warmth/touch Olfaction

Answer 116

Glomeruli can be in or off so this allows for a vast array of odour maps 2^N N - number of odour receptors Vast number of odours can be distinguished

Answer 117

Odour + reward = increased activation Odour + danger = increased activation

Answer 118

One associated with innate odour properties One associated with learning

Answer 119

Olfactory cortex Piniform cortex Parts of amygdala

Answer 120

May help in encoding information about concentration

Answer 121

Involved in: Categorising odours with hedonic value Memorising odours Perceiving similarity Integrating olfactory information with information from other sensory systems

Answer 122

Direct molecules to olfactory epithelium Better odour detection

Answer 123

Nostril movement Respiratory muscles

Answer 124

Nostrils sample separately Lateralisation of sniffing Ipsilateral information from nostril to hemisphere Right hemisphere deals with arousing stimuli Right nostril bias for arousing odours Neutral stimuli - first right nostril sniff- novelty and then shift to left nostril sniff

Answer 125

Bilateral sampling for odour localisation

Answer 126

Ipsilateral

Answer 127

Back flow of air creates turbulence Does not disrupt odour

Answer 128

Ruffini’s endings Krause’s end bulbs Pacinian corpuscle

Answer 129

Meissner’s corpuscle Merkel disks Root hair plexus

Answer 130

Free nerve endings

Answer 131

Ruffini’s endings

Answer 132

Krause’s end bulbs

Answer 133

Dorsal root ganglion of a spinal nerve Or Ganglia of the trigeminal or cranial nerves

Answer 134

Thalamus Or Cerebellum

Answer 135

Spinal cord

Answer 136

Post central gyrus of the parietal lobe Forms a sensory homunculus in the case of touch

Answer 137

Thalamus For posture- in the cerebellum

Answer 138

Detection of noxious stimuli by nociceptors

Answer 139

Unpleasant emotional and sensory experience Product of processing in the brain

Answer 140

An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage

Answer 141

Free, branching, unmyelinated nerve endings Sub population of peripheral nerve fibres In skin, joints, viscera, bone and muscle Detect thermal, mechanical or chemical stimuli suggestive of injury - ongoing inflammation

Answer 142

Thermal Mechanical eg cut Chemical Mechanical stress Chemical inflammation Mechanical distension Traction Chemical irritants Strenuous mechanical exertion Chemical modalities

Answer 143

Damaged tissue releases and produces factors activate nerve endings eg potassium, histamine and serotonin or bradykinin, prostaglandins or leukotrienes

Answer 144

Transducer channels, initiates receptor potentials and induces an action potential

Answer 145

A-delta C fibres

Answer 146

Medium diameter Myelinated Convey an acute, well-localised fast pain

Answer 147

Small diameter Unmyelinated Convey a poorly localised slow pain

Answer 148

Thalamus Amygdala Hypothalamus Periaqueductal grey Basal ganglia Brain stem reticular formation

Answer 149

Inputs from the frontal cortex and hypothalamus Outflow is through the midbrain and medulla to the dorsal horn of the spinal cord Inhibits pain-transmission cells, thereby reducing the intensity of perceived pain

Answer 150

Action potential in sensory neuron sends an excitatory postsynaptic potential (EPSP) to a somatic motor neuron in the spinal cord —> activates multiple reflex pathways—> stimulate the flexor muscle of the ipsilateral limb causing withdrawal Also activate an inhibitory postsynaptic potential to inhibit extensors of ipsilateral limb Also activates an interneurons that decussates and crosses the spinal cord midline —> stimulates a contralateral extensor muscle —> crossed-extension reflex (postural support)

Answer 151

Regulate the neurotransmission of pain signals Activation = reduction in neurotransmitter release and cell hyperpolarisation, reducing cell excitability and thus action potential generation

Answer 152

Can modulate pain physiologically

Answer 153

Eg morphine Act on receptors Analgesia

Sensory Systems Flashcards

(189 cards)