2. Stimulus – a change in the external or internal
environment that is detected by a receptor and
brings about a response.
Response – change in an organism due to a
stimulus.
Reflex – a rapid and “unconscious” response
Require a precise pathway – at least 3 synapses
Include 6 parts: >>>>>>>>>>>>>>>>>>>
REFLEXES and REFLEX ARCS
3. Receptor – detects stimulus, transforms into an impulse
Sensory Neurons –
part of the PNS
connects receptor to CNS thru dorsal nerve root
Impulse travels freely along the axon
Relay Neuron –
receives messages from sensory neurons across
synapses - passes them to motor neurons
Within gray matter of spinal cord
4. Motor Neurons –
Part of the PNS
Carries impulse from CNS (relay neuron) to
effector (muscle)
Leaves thru ventral root of SC
Cell body is in gray matter SC
Gray Matter – region of synaptic connection in
the SC
Effector – carries out response
5.
6.
7.
8. The mechanism of evolution- requires:
Variations in phenotypes
Genetic basis for variation
Change in the environment
Examples: 2 related to global warming:
Sylvia atricapilla – Black Cap - migration
Parus major – Great tit - breeding
9.
10. MIGRATION PATTERNS
Normal breeding – early summer across central and
northern Europe.
Then migrates to warmer areas before winter.
Patterns show normal migratory pattern – Germany to Spain
Recent studies – 10% migrating to the UK
Experiments show that direction of migration is
genetically inherited.
11.
12. Breed in spring/early summer through Europe.
Timing of egg laying is genetically programmed
Day length determines time of year.
Recent studies have shown that egg laying time is
becoming earlier.
Have greater reproductive success
due to earlier opening of leaves on trees & biomass that feeds
on the leaves –
Biomass – food for the great tit!
13. Types of Receptors
Mechanoreceptor – pressure, texture, vibrations (ear)
Chemoreceptors – chemical solutes and vapors
Photoreceptors – react to light
Thermoreceptors – change in temperature
14.
15. Choroid – light absorbing pigment; stray light
Retina – receptors for vision; rod cells
Fovea – densely packed cone cells; acute vision
Optic nerve – carries nerve impulses to brain
Optic disk – blind spot
Vitreous humor – supports eye; transparent
Lens – focuses light
Aqueous humor - supports eye; transparent
Pupil – light enters here
Iris – regulate size of pupil
Cornea – outer layer; fixed focusing
Sclera and conjunctiva – white; protects and supports
Rod cells – black and white sensors; dark light
Cone – color sensors; bright light
18. Rod cells Cone cells
Light brightness
Diversity of cells
Wavelength sensitivity
Impulse: neuron ratio
distribution
19.
20.
21. Edge Enhancement – pre
central nervous system;
carried out on the retina
itself.
22.
23. Gray areas – peripheral vision; fewer light sensitive
cells
Focused attention on any gray area – use center of
the retina.
24.
25. Contralateral Processing – is
the way the brain collects and
integrates information to
create the perception of
seeing.
26.
27. Both eyes send information and sends to both sides
of the brain.
n Optic chiasm – where information crosses to the
other side of the brain
e Both eyes are responsible for processing information
from both eyes.
28. HOW DOES VISION WORK
BLIND SPOTS
OPTICAL ILLUSIONS
29.
30. 1. Eardrum – pressure waves causes the eardrum to vibrate
2. Hammer, Anvil, Stirrup – eardrum pushes on bones of the
middle ear; magnifies 20x.
3. Oval Window – middle ear bones push on membrane ; causes
cochlea to move
4. Cochlea – pressure wave travels through fluid
r Sensory cilia in cochlea move
Causes the release of neurotransmitters between receptor and auditory
nerve.
s Auditory nerve – generates an impulse.
Impulse is carried to the brain for translation
________________________________________________
Semicircular canals – responsible for balance
Eustachian Tube – functions to equalize air pressure and drains
mucus
Hearing Test
31. Learned Behavior Innate Behavior
Experience Instinctive
Modified by trial and Genetically based
error Not modified
Variation within Uniform throughout
population population
Affected by environment Unaffected by
Capacity to learn may environment
product of natural Beneficial behaviors
selection rather than product of natural
specific behaviors selection
Learned or Innate??
32. INNATE LEARNED
Sucking instinct
Emotional expressions
Training animals
Birds hatching
Walking
Migratory patterns
Learning to drive
Hunting instinct
Tying shoes
Not breathing
underwater
Courtship and sexual
behavior in species
Reflexes – all
Instincts
33. A directional response to a stimulus:
Positive or Negative
Chemotaxis – response to chemicals
Phototaxis – response to light
Gravitaxis – response to gravity
Rheotaxis – response to water current
Thigmotaxis – response to touch
Paramecium
34. Response to a non directional stimulus:
Humidity – a non directional stimulus
Orthokinesis – speed of movement altered
Klinokinesis – rate of turning
35. Allows an organism to
change or adapt in
response to the
environment which gives
an increased chance of
survival
36. Non-associative Associative
Habituation – repeated stimulus Imprinting – learned early in
brings about decreased life – very receptive
response. No reward or Forms instant bond with one
punishment who provides the essential skills
Sensitization – increased for survival
response to a stimulus after a Conditioning – reward or
punishing stimulus punishment
Classical – Pavlovian
Crow Response Operant – behave to win award
or avoid punishment
Training
A good example
38. 1. Unconditioned Response – automatic to the
stimulus (food elicits salivation)
2. Neutral Stimulus – no response (bell ringing)
3. Conditioning – neutral and unconditioned
combined (dog associates bell with food and
salivates)
4. Conditioned Stimulus and Response (dog will
salivate when bell rings – even without food)
Example Example
39. Watch the video: To what extent do cowbirds learn
their sons socially and how much is innate?
Birdsong and Culture
Birdsong
Strong indicator of reproductive fitness
Females select males based on RF
Exaggerates traits - Lyre
40.
41. How do neurons talk to each other?
Through the SYNAPSE.
Most are chemical.
2 main types:
Excitatory – normal synapse.
Neurotransmitter released by presynaptic neuron (axon)
Causes positive ions to enter the post synaptic neuron
(dendrite)
Acetylcholine and dopamine
Inhibitory
Opposite effect – carry negative ions – Chloride - - into the
post synaptic neuron. Increases polarization –
hyperpolarization.
Makes it difficult to produce an action potential
Dopamine and GABA
42.
43. Important Points:
Axons of many neurons feed into the dendrite of the post synaptic
neuron.
Each axon contributes to a membrane potential.
The effects of each can be excitatory or inhibitory.
The effect is summative---- and if it reaches Threshold, an AP is
propagated.
Effects of excitatory neurotransmitters can be cancelled by inhibitory
neurons.
AP at postsynaptic neuron is determined by summation of
messages.
HOW IT WORKS!
45. Cholinergic vs. Adrenergic
Cholinergic –
Synapses using acetylcholine as the neuroT
Acetylcholine – parasympathetic of PNS
Importance in keeping “normalcy”
Response = relaxing
inhibitory
Adrenergic –
Synapses using noradrenalin as the neuroT
Noradrenalin – sympathetic of PNS
Importance for “alertness,” increased energy, & euphoria
stimulant
46. Excitatory Drugs
Nicotine –
similar to acetylcholine --- fits in receptor
Mimic excitatory neurotransmitters/ block inhibitor
Is not broken down by enzymes - remains
47. Excitatory Drugs
Amphetamines –
stimulate release of noradrenalin and
dopamine
Moves directly into pre-synaptic neuron
vesicle.
Results increased awareness and energy
48. Excitatory Drugs
COCAINE –
Normal
Dopamine and adrenaline act as excitatory neurotransmitters
Both usually taken back up at the pre synaptic axon or enzyme.
With Cocaine
Blocks receptors on the re-uptake pump
NT/hormone remains and more is released
Increases post-synaptic transmission
Changes –
Dopamine is a pleasure NT
Euphoria, increased energy, alertness
Highly addictive – body produces less natural dopamine
49. Inhibitory Drugs
BENZODIAZAPINES
(gamma-Aminobutyric acid) main
inhibitory NT
Enhance the effect of GABA (main
inhibitory NT)
Combines with and slows down GABA
receptors on post-synaptic neurons
Slows down brain activity.
50. Inhibitory Drugs
Alcohol
Initially acts as a stimulant
Release of dopamine
As level of BAC raises – has a
sedative effect
Increases binding of GABA
Acts as an anesthetic
51. Inhibitory Drugs
Tetrahydrocannabinol
Cannabis –
Normal
Dopamine and GABA proceed when needed
With THC
THC inhibits GABA release
GABA cannot inhibit dopamine
Mood and Behavior
Increased feelings of pleasure
Intoxicated, hunger, memory loss,
Used to treat nausea in cancer patients.
52. ADDICTION (Mouse Party)
A chronic neurological disorder
with:
Genetic characteristics
Psychosocial characteristics
Environmental characteristics
Changes in the brain result in
compulsive desire to use a drug
53. General Causes of Addiction
Genetic – not fully understood
Different allele for a receptor?
Carry modified versions of genes linked to drug
metabolism
Susceptibility does not mean inevitability.
Psychosocial/ Environmental
Peer pressure
Timing
Availability
Legality/Religion
Community
Family
Mental health