Lecture 2 Flashcards
(153 cards)
1
Q
What are the two primary divisions of the nervous system?
A
Central nervous system (CNS) and Peripheral nervous system (PNS)
2
Q
What are the two primary divisions of the peripheral nervous system (PNS)? Describe each.
A
1) Afferent: Sensory and organ systems transmit into TO the CNS
2) Efferent: Communication FROM the CNS to organs/motor function
3
Q
What 3 things do neurons consist of? Describe each
A
1) Cell body/soma
2) Dendrites: project from cell body to receive signals
3) Axon: the nerve fiber that carries action potentials away from cell body
4
Q
1) How long are axons?
2) What is the axon trigger zone?
3) What are the final branches of an axon called?
A
1) Can very in length, 1 mm to longer than 1 meter
2) Axon hillock (initial segment)
3) Axon terminals
5
Q
1) What is myelination formed from in the PNS?
2) What about in the CNS?
A
1) By Schwann cells in the PNS
2) Oligodendrocytes in the CNS
6
Q
1) What is myelinated conduction also called?
2) How fast is it compared to unmyelinated?
3) What are the nodes of ranvier?
A
1) Saltatory conduction
2) 50 times faster
3) The gaps between myelinated sections
7
Q
What are the 3 morphological classifications of neurons? Briefly describe each
A
1) Unipolar: Usually afferent
2) Bipolar: Rare, found in retina
3) Multipolar: Most common
8
Q
1) What is neuronal transport mediated by?
2) Define anterograde transport
3) Define retrograde transport
A
1) Cytoskeletal components
2) Anterograde: From soma to processes
3) Retrograde: From the process to the soma
9
Q
1) List the 3 cytoskeletal components
2) Which is made of actin/ myosin?
3) Which is also in organelle transport?
A
1) Neurofilaments, microfilaments, and microtubules
2) Microfilaments
3) Microtubules
10
Q
What two proteins aid microtubules?
A
Kinesin and dynein
11
Q
List and describe the 3 primary cytoskeletal components (involved in the mediation of neuronal transport)
A
1) Neurofilaments: Structural rigidity to the axon
2) Microfilaments: Extension of dendrites and axon, structural support and organelle transport
Composed of actin/myosin
3) Microtubules: Largest in diameter, also in organelle transport. Aided by proteins kinesin and dynein.
12
Q
1) What fibers conduct at .7 meters/ sec?
2) What fibers conduct at 120 meters/ sec?
A
1) Small unmyelinated fibers of digestive tract
2) Large myelinated skeletal muscle fibers
13
Q
1) Name a disease in which myelin is destroyed, and what kind of disease it is.
2) What else does the damage from this disease do?
3) What 4 observable effects does this disease have on the body?
A
1) Multiple sclerosis; an autoimmune disease
2) Also leaves scars which further interfere with transmission
3) Affects muscle weakness, balance, coordination, sensation
14
Q
1) What two things do Schwann cells do? Where are they found?
2) What stabilizes the complex structure of the CNS? When does this happen?
3) Can the brain and spinal cord regenerate?
A
1) Repair and regulate; only in the PNS
2) Growth inhibiting proteins of the CNS; activated late in fetal development
3) No, brain and spinal cord don’t regenerate
15
Q
1) What do neurons regulate? What does this result in?
2) What 3 things are needed for neuronal excitability?
A
1) The transport of specific ions across neuronal membranes resulting in an electrochemical gradient
2) Na+, K+ and Cl-
16
Q
1) What are the two types of ion channels?
2) What creates an electrical gradient?
3) What is most cells RMP (resting membrane potential) dominated by? Why?
A
1) Voltage gated and ligand gated
2) Different concentrations of ions
3) K+; due to the permeable plasma membrane
17
Q
True or false: Action potentials (APs) always have the same phases
A
False; APs have different phases depending on the permeability
18
Q
1) How do voltage gated channels work?
2) Regarding these channels, what happens at threshold potential?
3) Is the ECF or ICF more positive after this happens?
A
1) The surrounding electrical environment changes their shape
2) Na+ becomes 600x more permeable than K+ and this sets off positive feedback of Na+ voltage gated channels opening
3) ICF becomes more positive than ECF
19
Q
Define absolute and relative refractory periods
A
1) Absolute: another AP cannot be generated
2) Relative: follows the absolute refractory period; an AP can only be generated by stronger than usual trigger during hyperpolarization
20
Q
Explain the “all-or-none” rule
A
A triggering event that is stronger than what is required for threshold potential does not create a “stronger” action potential, and a trigger event that “comes close” to threshold potential does not active an action potential at all
21
Q
1) What two things affect the speed of an action potential
2) What type of conduction occurs in unmyelinated fibers?
3) What about in myelinated fibers?
A
1) Diameter and myelination of the fiber
2) Contiguous conduction
3) Saltatory conduction
22
Q
What are the two ways neurons communicate?
A
By electrical and chemical synapses
23
Q
1) How do electrical synapses occur?
2) What do chemical synapses rely on?
3) What are the 3 ways in which a chemical synapse can be terminated?
A
1) Occurs via gap junctions
2) The release of neurotransmitters
3) Via diffusion, degradation, or cellular uptake
24
Q
1) Where is acetylcholine released from?
2) What 3 non-CNS things is norepinephrine involved in?
3) What 6 CNS pathways is norepinephrine involved in?
A
1) From nerves that supply muscle and exocrine glands
2) Smooth muscle, cardiac muscle, exocrine glands
3) Pathways for memory, mood, emotion, behavior, perception, sleep
25
1) What pathways is dopamine involved in?
2) What 5 pathways is serotonin involved in?
1) Similar CNS pathways to norepinephrine; “Pleasure” pathways.
2) CNS pathways for mood, behavior, stress, consciousness, muscles
26
What do SSRIs do?
Block the reuptake of serotonin in the presynaptic axon terminals, prolonging its action
27
1) What are neuromodulators involved in?
2) Give 4 examples
1) Long-lasting events like learning and motivation
2) Neuropeptides, ATP, nitrous oxide, and endocannabinoids (similar to the active ingredient of marijuana)
28
What are the two types of postsynaptic potentials? What does each do, and what does this cause to happen?
1) Excitatory postsynaptic potentials (EPSPs): bind to receptor-channels that permit Na+ and K+, and bring the postsynaptic membrane closer to threshold potential
2) Inhibitory postsynaptic potentials (IPSPs): Increase permeability of K+ (efflux) or Cl-, causing small hyperpolarization
29
1) Define direct communication and give 3 examples
2) What type of communication is indirect?
1) Physical contact between cells. Exs: Gap junctions, tunneling nanotubes, and surface markers
2) Chemical messengers
30
1) What are the 4 types of signal molecules?
2) What type of communication are they involved in?
1) Paracrines/autocrines, neurotransmitters, hormones, and neurohormones
2) Indirect (chemical) communication
31
The sequence in which incoming signals from extracellular chemical messengers are conveyed to a target cell to elicit a specific cellular response is called what?
Signal transduction
32
1) What do paracrines act on?
2) What do autocrines act on?
3) What do neurotransmitters act on?
1) Act on cells near area of secretion.
2) Act only on the cells that secreted it.
3) Act across the synaptic cleft
33
1) What are hormones? What do they affect?
5) What are neurohormones released by? What do they affect?
1) Long-range chemicals carried by the blood to affect specific target cells
2) Released by neurosecretory neurons into the blood to act on distant cells
34
Define signal transduction
Sequence in which incoming signals from extracellular chemical messengers are conveyed to a target cell to elicit a specific cellular response
35
Most paracrines belong to what two categories?
Cytokines or eicosanoids
36
1) Cytokines or eicosanoids are two types of what?
2) What is that category a type of?
1) Paracrines
2) Signaling molecules
37
1) Describe cytokines
2) What 3 things are cytokines involved in?
1) Immune-mediators that enhance antibody-producing cells
2) Growth, cell differentiation, and healing
38
1) Define eicosanoids
2) What are its 3 classes?
1) Lipid signal molecules involved in many functions
2) Prostaglandins, thromboxanes, and leukotrienes
39
1) What did we initially think was the sole function of prostaglandins? What else are they actually involved in?
2) What two things do thromboxanes promote?
3) What are leukotrienes involved in?
1) Initially thought to only be involved in reproduction, but are involved in many body systems including respiratory, digestive, urinary, etc
2) Platelet aggregation and vasoconstriction
3) Inflammatory responses
40
What are the two main types of hormones?
Hydrophilic and lipophilic
41
1) What are hydrophilic hormones made of? What are the two types?
2) What are catecholamines secreted by?
3) What are indoleamines secreted by?
1) Made of amino acid chains: proteins (longer) and peptides (shorter)
2) Adrenal medulla
3) Pineal gland
42
1) What are catecholamines and indoleamines a type of?
2) What is that a type of?
1) Hydrophilic hormones
2) Signaling molecule
43
What hormones are lipophilic?
Thyroid and steroid hormones
44
1) What sites does the nervous system affect? What about the endocrine system?
2) How long do nervous system transmissions take, and how long do the effects last? What about the endocrine system?
3) What can be described as "wired", the nervous system or endocrine system? Which can be described as wireless?
1) Nervous system affects close sites; endocrine system affects distant sites
2) Nervous system takes milliseconds and lasts for milliseconds. Endocrine system takes minutes to hours, and lasts minutes to days or longer
3) Nervous as "wired", endocrine as “wireless”
45
1) What do sensory systems do? In what form?
2) Name 6 kinds of sensory receptors
1) Transform physical and chemical signals from the external and internal environments into information in the form of nerve action potentials
2) Photoreceptors
Chemoreceptors
Mechanoreceptors
Thermoreceptors
Proprioceptors
Nociceptors
46
List 4 characteristics of sensory receptors
1) Optimized to respond preferentially
2) Most receptors will respond to additional types of stimuli (but threshold is higher)
3) Transform environmental energy into electrical signals
4) Have a graded response (depends on signal strength)
47
1) Define adequate stimulus in the context of sensory receptors
2) What do accessory sensory structures do?
1) The lowest threshold detected
2) Enhance the sensitivity of the receptor
48
In regards to sensory nerve activity:
1) What happens to the membrane when there's no stimulus?
2) What does a subthreshold stimulus produce?
3) What can cause a single action potential?
4) What happens if a stimulus is maintained?
5) What would increasing stimulus intensity do?
1) The membrane is at rest.
2) A generator potential too small to cause membrane excitation.
3) A brief, but intense, stimulus
4) Leads to a train of action potentials.
5) Would lead to an increase in the action potential firing rate.
49
1) Do larger responses produce larger APs (action potentials)? Why?
2) What can produce more action potentials?
1) No, bc of all-or-none law can only make more APs
2) Increased intensity can induce more AP’s
50
1) Define slow adaptation
2) Define rapid adaptation
3) Define tonic
4) Define phasic
1) Generator Potential amplitude declines slowly
2) Action potential frequency falls rapidly and than maintains a constant slow rate that does not show further adaptation
3) Tonic: Little or no adaptation (intensity receptors)
4) Phasic: Significant adaptation (velocity receptors)
51
What type of receptors are tonic? Which are phasic?
Intensity receptors are tonic, velocity receptors are phasic
52
List 6 kinds of sensory receptors
1) Tactile (touch) type of mechanoreceptor
2) Hair receptor
3) Merkel’s disc
4) Pacinian corpuscle
5) Ruffini endings
6) Meissner’s corpuscle
53
1) How do tactile (touch) type of mechanoreceptors work?
2) What do hair receptors allow us to sense?
3) What does Merkel’s disc allow us to sense?
1) Mechanical force changes cation channel proteins, Na+ entry, afferent AP
2) Gentle touch
3) Sustained touch and texture like when reading Braille
54
1) What does the Pacinian corpuscle allow us to sense?
2) What does the Ruffini endings allow us to sense?
3) What does the Meissner’s corpuscle allow us to sense?
1) Pacinian: Vibration, deep pressure
2) Ruffini: Slow sustain sensation (like massage)
3) Meissner’s: Rapidly adapting and sensitive (tickling with feather)
55
Trace the path of afferent information
1) Starts in the periphery
2) Goes to the spinal cord then
3) Becomes part of reflex arc
OR
3) Relayed to the brain via ascending pathway for further processing
56
What two things can happen once afferent information reaches the spinal cord?
It becomes part of reflex arc
OR
It's relayed to the brain via ascending pathway for further processing
57
Why can we feel thermal sensations in different gradations (i.e. the difference between hot and warm, warm and cool, etc)?
Because of three types of sensory receptors:
1) Cold receptors
2) Warmth receptors
3) Pain receptors
58
1) True or false: Different thermal receptor subtypes are activated at different temperatures
2) How are they activated?
3) What does this all facilitate?
1) True
2) Perhaps activated by changes in their metabolic rates, which would vary through different temperature windows
3) Graded sensation of temperature
59
Where do thermal receptor signals enter and terminate?
1) Enter ascending fibers in the anterolateral tract and 2) Terminate in the brain stem and thalamus
60
1) How does vision work; what detects light, and what processing does it undergo?
2) Name two properties of the eye
1) Light bounces off objects, which is then detected by photoreceptors in the retina. Undergoes cortical processing to provide the sensation of vision
2) Sensitive and valuable
61
How many layers is the eye made of? List and describe them
1) Corneoscleral layer: tough connective tissue
2) Uveal layer: richly vascularized
3) Retina: photoreceptor cells
62
1) Define vision
2) What is the iris? What does it do?
3) Name two parts of the iris and what they do
1) Process by which eyes turn light into sensation of vision
2) Smooth muscle which regulates the size of the pupil which determines how much light enters
3) a) Circular muscles: contract to make pupil smaller in bright light
b) Radial muscles: contract to make pupil larger in dim light
63
1) What muscle contracts the pupil smaller, and when does it do this?
2) What muscle contracts the pupil larger? When?
1) Circular muscles: contract to make pupil smaller in bright light
2) Radial muscles: contract to make pupil larger in dim light
64
1) Where is the anterior cavity of the eye?
2) What does it contain?
3) What does that contain? Why?
1) Between cornea and lens
2) Aqueous humor
3) Nutrients for cornea and lens; because they lack blood supplies
65
1) Define glaucoma
2) What can help control it? In which was can it be controlled?
1) When the aqueous humor is not drained appropriately
2) Different medications can be used to either increase drainage and/or decrease production
66
What are the refractive structures of the eye?
Cornea and lens
67
1) Describe the shape of the cornea
2) What occurs as light passes through here?
3) Is the difference in density larger between the air and cornea, or the fluid and lens?
1) A curved surface area
2) Most of the refraction
3) Difference in density is larger at air-cornea than fluid-lens
68
1) What is astigmatism?
2) What does it cause?
3) What does that do to vision?
1) Irregularity in the curvature of the cornea
2) Light rays to be refracted unequally
3) Becomes distorted
69
1) Define accommodation (in relation to the eye)
2) What regulates this?
3) What is that a part of?
1) The ability to adjust the strength of the lens
2) The ciliary muscle
3) Part of the ciliary body
70
1) What are the ligaments doing when the ciliary muscle is relaxed? What about when contracted?
2) What is the lens doing when the ciliary muscle is relaxed? What about when contracted?
3) What type of vision is a relaxed ciliary muscle good for? What about contracted?
4) Which is the default position, a relaxed ciliary muscle or a contracted one?
1) When ciliary muscle is relaxed, ligaments are taut. When it's contracted, ligaments are slackened
2) Lens is flat (weak) when relaxed, and rounded (strong) when contracted
3) Relaxed is better for far away objects, contracted is better for nearby objects
4) Default position is relaxed
71
1) What is the lens made of?
2) Why?
1) Lens is made of 1000 layers of cells that destroy their nucleus and organelles
2) Makes them transparent
72
1) What cells of the lens are father from the aqueous humor?
2) How does being far from the aqueous humor affect those lens cells?
1) Cells in the center of the lens
2) Increases their likelihood of death and stiffening with age
73
1) How does stiffening of the lens affect its function?
2) What does this cause? Define it
1) Affects their ability to change shape for accommodation
2) Presbyopia: age related nearsightedness
74
Transparent fibers in the lens can become opaque; what is this called?
Cataracts
75
1) What word means normal vision?
2) What is the ciliary muscle doing during normal vision?
3) Where is the light source? Is accommodation occurring?
1) Emmetropia
2) Ciliary muscle relaxed (no accommodation)
3) Light source from a far object is focused onto the retina without accommodation
76
1) What is the other word for nearsightedness?
2) What is focused without accommodation with nearsightedness? What is blurry?
3) What are two reasons for nearsightedness?
4) How is nearsightedness corrected?
1) Myopia
2) Nearby objects focused onto the retina without accommodation; far objects are blurry
3) Eye is too long or lens is too strong (wide)
4) With a concave lens
77
1) What is the other word for farsightedness?
2) What is focused without accommodation with farsightedness? What is blurry?
3) What are two reasons for farsightedness?
4) How is farsightedness corrected?
1) Hyperopia
2) Far objects require accommodation; near objects are blurry even with accommodation
3) Eye is too short or lens is too weak (flat)
4) Corrected by convex lens
78
The inner nervous tissue layer of the retina also has layers (3); what are they? Describe what each contains
1) Outer: Rods and cones
2) Middle: Bipolar cells, interneurons
3) Inner: Ganglion cells and axons form optic nerve
79
1) Where does light pass through before reaching rods and cones?
2) What is the exception?
1) Light passes through inner and middle layers of retina before reaching rods and cones
2) Except for in the fovea
80
1) What is the center of the retina called?
2) Are the rods here, cones here, or both?
3) How does light hit this part of the retina?
4) Describe this part of vision
1) Fovea
2) Only cones here
3) Light hits directly
4) Point of most distinct vision; sharp, central vision
81
1) Define macula lutea
2) What does it have a high concentration of?
3) Describe vision here, and why it's like this
1) Area surrounding fovea
2) Also has high cone concentration
3) Vision not as acute here (as fovea) due to overlying ganglion and bipolar cells
82
1) What is macular degeneration?
2) What happens?
3) What does this do to vision?
1) Degeneration of the macula
2) Photoreceptors die from various causes
3) Central vision loss
83
What is the Leading cause of blindness in Western Hemisphere?
Macular degeneration
84
What are the photoreceptors of the eye?
Rods and cones
85
1) What are rods and cones?
2) How many parts do rods and cones consist of? List them.
3) What direction does information travel through the rods and cones?
4) What are rods and cones made of?
1) Photoreceptors in the back of the retina that are rod shaped or cone shaped
2) Consist of three parts; outer segment, inner segment, and synaptic terminal
3) From outer to inner direction
4) Light sensitive photopigments
86
1) Define photopigments and what they do
2) How many photoreceptors does each retina have?
3) How many photopigments does each retina have?
1) Unstable chemicals that react to light; generate receptor potentials
2) ~125 million photoreceptors
3) ~1 billion photopigments
87
1) What do rods do?
2) What pigment do they contain?
3) What are the two components of this pigment?
4) What is retinal derivative of, and what does it do?
1) Rods (light vision)
2) Pigment: rhodopsin
3) Rhodopsin components: Opsin and retinal
4) Derivative of Vit A; changes conformation in light vs dark
88
1) What do cones (of the eye) do?
2) What do they contain? What do those do?
1) Color vision
2) 3 opsins (RGB)
89
What's the difference between rods and cones?
Rods do light vision, cones do color vision
90
1) How many rods per retina ? What about cones?
2) Are rods good for day or night vision? What about cones?
3) Which is high sensitivity, rods or cones?
4) Which is high acuity, rods or cones?
5) Where are rods most numerous? What about cones?
6) Which has a lot of convergence in retinal pathways?
1) 120 million rods; 6 million cones
2) Rods for night vision, cones for day vision
3) Rods are high sensitivity
4) Cones high acuity
5) Rods are most numerous in periphery, cones are concentrated in fovea
6) Rods
91
1) How many cones connect to a ganglion?
2) Why?
3) How many rods connect to a ganglion?
4) Why?
1) One connects to one ganglion cell
2) So there's a dedicated line to retinal surface, sending info from much smaller receptive field, leading to MORE DETAIL
3) More than 100 rods can connect to one ganglion
4) More convergence = more likely to bring cell to action potential, so makes it more sensitive
92
1) When can rods generate APs? What about cones?
2) What makes rods less detailed than cones?
1) Rods can generate AP’s in dim light but cones need bright light
2) Cannot discern which rod’s receptive field activated the AP because multiple rods converge on one ganglion cell, so less detail
93
What do pigments of objects in the environment do?
Selectively absorb particular wavelengths; remaining wavelengths are reflected
94
1) What is the trichromatic theory of color vision?
2) How does blue stimulate the cones? What's the ratio?
3) How does yellow stimulate the cones? What's the ratio?
4) How does green stimulate the cones? What's the ratio?
1) The idea that the perception of color depends on ratios of stimulation of the three cones
2) Blue stimulates blue cones maximally and not at all for red and green: 0:0:100
3) Yellow stimulates red and green: 83 red: 83 green: 0 blue
4) Green stimulates all 3:
31:67:36
95
What does perception of color depend on?
Ratios of stimulation of the three cones
96
What is the lateral genticulate nucleus and what does it do?
Relay center in thalamus; receives input from retina & transmits info to the primary visual cortex
Massive amount of input
97
1) Where are visual signals sent?
2) What does this location do to the images?
3) True or false: signals are processed in only one way.
4) True or false: the same part of the brain is responsible for all visual recognition
1) Signal is sent to primary visual cortex in the occipital lobe
2) The inverted image (upside down and backwards) is brought to correct orientation
3) False; signals are processed in several ways
4) Fales: faces are recognized by a different region than inanimate objects
98
1) Each half of the cortex receives information from where?
2) How does each eye view the same object?
1) From the contralateral field of both eyes
2) Each eye views the same object from a slightly different vantage point
99
What is responsible for our depth perception?
Since each eye views the same object from a slightly different vantage point, that slight disparity in the images is processed by the brain as perceived as depth
100
1) True or false: Visual information is modified in many ways on its way to its destination
2) What is its destination?
1) True
2) The primary visual cortex in the occipital lobe
101
1) Describe the orientation of the original image. Why is it this orientation?
2) What do retinal neurons do? Why?
3) What is this an example of?
1) Upside down and backwards; due to refraction on the retina
2) Retinal neurons suppress and/or enhance visual information to increase contrast and sharpness
3) Modification of visual information before it reaches the brain
102
1) What does one half of the visual cortex receive information from?
2) Why?
1) From the opposite half of both eyes
2) “Wiring”
103
Where is vision processed?
The primary visual cortex in the occipital lobe
104
1) Define hearing
2) What can produce sound?
1) The neural perception of sound energy
2) Anything that disturbs the air molecules a manner that produces sound waves
105
1) Define sound waves
2) What are the regions of sound waves? What causes each to form?
1) Vibrations of air, with regions of:
2)
A) High pressure: from air molecule compression
B) Low pressure: from air molecule rarefaction (decrease in density)
106
1) What do the external and middle ears do for hearing?
2) What does the inner ear do for hearing?
1) External and middle ears transmit sound waves to the inner ear
2) Inner ear converts these into nerve impulses
107
What is another function of the inner ear besides hearing? What part of the inner ear does this?
Houses vestibular apparatus, which is necessary for sense of equilibrium
108
List and define the 3 parts of the external ear
1) Pinna (ear): Channels soundwaves down the ear canal; orientation helps w direction detection
2) External auditory meatus (ear canal): Tunnel from exterior to the eardrum
3) Tympanic membrane (eardrum): Separates external from middle ear; bows in and out
109
1) What does orientation of the pinna (ear) do?
2) What does the tympanic membrane do?
1) Orientation helps with detecting direction
2) Bows in and out in response to compressed and rarefied air molecules
110
1) What must happen in order for TM to properly bow in and out?
2) How is the outside of the ear exposed to the atmosphere?
3) How is the inside of the ear exposed to the atmosphere?
1) The air pressure must be equal on both sides
2) Outside the ear: [entirely] exposed to atmospheric pressure
2) Inside: exposed to atmosphere via eustachian (auditory) tube connecting the middle ear to pharynx
111
Why do kids have more ear infections than adults?
Eustachian tube is straighter in kids
112
1) What does the middle ear accomplish?
2) What facilitates this? List each of its 3 parts.
3) What does it produce?
1) Transfers TM vibration to the inner ear fluid
2) Facilitated by a chain of bones (ossicles): Malleus, incus, stapes
3) Wavelike movements in inner ear fluid at the same frequency as the sound waves
113
1) What does the organ of Corti do?
2) Where is it found?
3) What forms its base?
4) What does the basilar membrane contain?
1) Generate nerve impulses
2) In the inner ear, specifically the cochlea
3) Basilar membrane forms base
4) Contains 15,000 hair cells, with each having 100 protrusions called stereocilia
114
1) What does the basilar membrane of the organ of corti do?
2) What does this trigger?
1) Fluid motion deforms its stereocilia
2) Mechanoreceptors
115
Intensity discrimination depends on what?
Amplitude of vibration; higher amplutide = louder sound
116
1) What determines pitch?
2) What determines loudness?
1) "Where” the basilar membrane vibrates
2) "How much” it vibrates
117
How sensitive is the auditory system? Describe it.
Extremely sensitive ; able to detect very faint sounds that deflect the basilar membrane to a fraction of the diameter of a hydrogen atom
118
1) What part of the ear can't protect against very loud sounds?
2) What can very loud sounds change about the ear?
3) What does this lead to?
4) What two things can lead to hearing loss?
1) The middle ear
2) Loud sounds can permanently distort hair cells
3) Leads to partial hearing loss
4) Brief exposure of high intensity or frequent exposure to moderate intensity (75dB)
119
What are the two types of deafness?
Conductive and sensorineural deafness
120
1) What is conductive deafness?
2) Give 3 potential causes
1) When sound waves not adequately conducted to inner ear
2) Physical blockage, TM rupture, infection
121
1) What is sensorineural deafness?
2) What 3 parts could be responsible for this?
1) When sound waves are not adequately translated into nerve signals
2) Organ of Corti, auditory nerves, or brain
122
1) Define neural presbycusis
2) Why does this happen?
1) Age-related degenerative hearing loss
2) Hair cells “wear out” even due to normal sounds
123
What type of deafness is neural presbycusis?
Conductive deafness
124
1) Average adult loses __% of cochlear hair cells by age 65 (increasing over time)
2) Do we lose high pitch or low pitch hearing first?
1) 40%
2) Lose high pitch first
125
What are chemoreceptors for taste sensation grouped into?
They're packaged into taste buds
126
1) How many taste buds in the oral cavity?
2) What does each taste bud have? What does this do?
3) How do taste buds work?
1) 10,000 taste buds in the oral cavity
2) Each taste bud has a taste pore, an opening through which fluids contact 50 taste receptor cells
3) Tastants bind to taste receptor cells, altering ion channels to produce receptor potentials
127
1) Where are taste signals sent?
2) Where are they then relayed to?
3) Where are they also sent, and what does this allow us to tell about a taste?
4) What part of taste does the hypothalamus process?
1) Terminal afferent endings send signals to brain stem and thalamus
2) Relayed to primary gustatory cortex in the lateral sulcus
3) Signals also sent to hypothalamus to identify them as pleasant or unpleasant
4) Behavioral aspects of taste
128
Thousands of taste sensations are a variation of how many types of taste
5
129
1) What is salty taste stimulated by?
2) What happens on a cellular level when you taste salt?
3) What is sour taste stimulated by?
4) What happens on a cellular level when you taste sour?
1) By NaCl, signals presence of electrolytes
2) Na+ enters cells, decreases internal negativity, depolarizes receptors
3) Acids (which have free H+)
4) H+ blocks K+ exit from cell, reducing negativity and depolarizing receptor
130
1) What is sweet taste stimulated by?
2) What happens on a cellular level when you taste sweet?
3) List 3 bitter tastants
4) What is umami taste triggered by?
1) Glucose
2) Activates chemical reactions that ultimately block K+
3) Morphine, caffeine, nicotine
4) Savory taste triggered by amino acids, especially glutamate
131
1) What happens on each side of the nose?
2) Where is this found and what are they lined with?
1) Afferent fibers synapse neural structures on each side of the nose
2) Olfactory bulbs; each is lined with neural junctions called glomeruli
132
1) What detects pheromones?
2) How does it work?
1) Vomeronasal Organ (VNO)
2) Binding of a receptor in the VNO triggers AP to the limbic system
133
When does most refraction occur? (in relation to vision)
As light passes through the cornea
134
1) Close to a light source, are light rays parallel?
2) What about at 20 feet?
1) No, light rays are still diverging
2) At 20 feet they are essentially parallel
135
What are cataracts?
When the transparent fibers in the lens become opaque
136
What is occurring in the eye when light is coming from a close source?
Lens strength (width) is increased to bring near source into focus, lens is round, ciliary muscle contracted
137
1) What layer of inner retinal nervous tissue contains the rods and cones?
2) What layer contains ganglion cells?
3) What layer contains bipolar cells and interneurons?
1) Outer
2) Inner
3) Middle
138
Where do axons form the optic nerve? (in relation to the eye)
In the inner layer of the inner retinal nervous tissue
139
What could happen if the fovea of the retina [of the eye] was damaged?
You could lose the sharpest, most central part of your vision
140
1) What is the optic disc?
2) Describe vision here?
3) Are there rods, cones, both, or neither here?
1) Region through which optic nerve and blood vessels pass
2) Blind spot
3) No rods or cones
141
1) Why aren't we aware of our blind spot?
2) What causes it?
1) Due to central processing “filling in” the spot
2) The optic disc; a region where there's no cones and the optic nerve (and vessels) pass through
142
What does retinal do? Where is it found?
Found in the rods of the retina; changes conformation in light vs dark
143
What would happen if you didn't have any vitamin A?
Your retinal, which are a part of the pigment rhodopsin that allows rods to work, so your light vision may be affected
144
1) What do normal receptors do when stimulated?
2) What do the photoreceptors do when stimulated during phototransduction?
3) Describe why this happens
4) What does light absorption do?
5) What does light do to the retina?
6) What does lack of light do?
1) Depolarize when stimulated
2) Photoreceptors hyperpolarize; different than most receptors
3) cGMP (chemical messenger) keeps chemically gated Na+ channels open
-Passive Na+ leak into rods
-Default: membrane depolarized
-Rod cell releasing glutamate (neurotransmitter)
4) Breaks down cGMP:
5) Changes retinal conformation
6) Triggers arrestin which blocks transducin
145
1) How are cones coded?
2) Where is color perception processed?
1) Cones are coded in separate pathways to the brain
2) Occipital lobe
146
Define prosopagnosia
Face blindness (can't recognize faces)
147
It takes more energy to vibrate liquid than air at a given frequency. The inner ear is filled with fluid. How does the middle ear deal with this?
The orientation of ossicles acts as a lever that amplifies the sound waves 20x
148
1) What generates nerve impulses?
2) What does the basilar membrane do?
3) What are the protrusions of hair cells called? Where are hair cells found?
1) Organ of Corti
2) Forms the base of organ of Corti
3) Stereocilia; found in basilar membrane
149
1) How do you distinguish high and low pitch?
2) What is this called?
1) Peak of the frequencies cause vibrations in specific parts of the basilar membrane of the cochlea
(i.e. different parts of the cochlea are activated at different frequencies)
2) The place theory of hearing
150
1) Describe how loudness is perceived; what are louder sounds physically causing the ear to do? (2 steps)
2) What part interprets this as loudness?
1)
A) Louder sounds strike the eardrum with more force, causing stronger vibrations of the cochlear fluid
B) This causes basilar membrane to move more at the peaks of the waves, causing greater bending of the hairs
2) CNS interprets this as loudness
151
1) How many taste receptor cells are found in each taste pore?
2) What do taste receptor cells respond to? How many of these can it respond to?
1) 50
2) Tastants; each taste receptor cell only responds to one
152
1) How many olfactory receptors does the human nose contain? Of how many types?
2) Describe the binding of receptors and odorants
3) What does binding cause?
4) What does this ultimately lead to?
1) Human nose contains 5 million olfactory receptors of 1000 types
2) Different parts of an odorant bind to different receptors, the receptor usually doesn’t bind to the entire odorant
3) A reaction cascade
4) Na+ and Ca+ entry and depolarization
153
Define glomeruli
Neural junctions that line each olfactory bulb
