Transcript E.4.4 List three examples of excitatory and three examples of

Option E
Keegan Murphy, John Rubenchik,
Enkhjin Myagmarsuren, Michal
Tesfemariam,
Define the terms stimulus, response and reflex in the context
of animal behaviour
Explain the role of receptors, sensory neurons, relay neurons, motor
neurons, synapses and effectors in the response of
animals to stimuli.
Draw and label a diagram of a reflex arc for a pain
withdrawal reflex.
-The central nervous system includes the brain and the spinal cord.
-The spinal cord acts independently from the brain during reflex actions.
-The reflex is an automatic response to specific stimuli.
-The reflex response is a fast involuntary reaction which increases the chance of
an animal avoiding damage and therefore increasing chances of survival.
Explain how animal responses can be affected by natural
selection, using two examples.
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Animal behaviour is more than a single reflex but a complicated series of
responses to the environment. Some populations of organisms have changed their
behaviour in response to a change in the environment.
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Variations in behaviour can occur in populations in the same way as variation in
the characteristic, such as colour, of the animals. The characteristic of an animal is
determined by genes just as behaviour can be determined by genes.
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Variations in behaviour can be selected by the environment. Since a genetically
programmed behaviour can have variations, one behaviour can work better than
another in a changing environment. The variation will allow one group of
organisms to survive and reproduce better in the new environment.
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The theory of natural selection states that the organism best fitted for the
environment is more likely to survive to reproduce.
Outline the diversity of stimuli that can be detected by
human sensory receptors, including mechanoreceptors,
chemoreceptors, thermoreceptors and photoreceptors
mechanoreceptors:
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membrane receptor proteins respond to mechanical deformation,
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which results in membrane depolarization
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leading to action potentials sent to brain,
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which interprets the sensation,
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e.g. Meissner’s corpuscle (light touch), Pacinian corpuscle (deep pressure), hair cells (hearing, balance), aortic baroreceptor (blood
pressure)
chemoreceptors:
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membrane receptor proteins bind specific molecules
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which results in membrane depolarization
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leading to action potentials sent to brain,
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which interprets the sensation,
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e.g. olfactory neurons, gustatory cells of taste buds, aortic carotid bodies, hypothalamic glucoreceptors
thermoreceptors:
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membrane receptor proteins respond to temperature,
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which results in membrane depolarization
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leading to action potentials sent to brain,
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which interprets the sensation,
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e.g. free nerve endings in dermis detect warmth; hypothalamic thermostat detects internal temperature
photoreceptors:
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photopigments change when activated by specific wavelengths of light,
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which results in membrane depolarization
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leading to action potentials sent to brain,
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which interprets the sensation,
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e.g. rods and cones in the retina of the eye
Label a diagram of the structure of
the human eye.
Annotate diagrams of the human retina to show the cell
types and the direction in which light moves.
Compare rod and cone cells
Explain the processing of visual stimuli, including edge
enhancement and contralateral processing.
edge enhancement:
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occurs within the retina
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two types of ganglion cell, each stimulated when light falls on a small circular area of retina called the receptive field
on-center ganglion cells
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off-center ganglion cells
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ganglion is stimulated if light falls on the center of the receptive field
but this stimulation is reduced if light also falls on the periphery
light falling on the periphery of the receptive field stimulates the ganglion cell
if light also fall on the center of the receptive field, stimulation is reduced
both types of ganglion cell are therefore more stimulated if the edge of the light/dark is within the receptive field
contralateral processing:
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signal passes from photoreceptor to bipolar neuron to ganglion cell,
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which leave the eye bundled in the optic nerve,
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left and right optic nerves meet at the optic chiasm
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neurons carrying impulses from the half of the retina nearest the nose cross over to the opposite optic nerve
thus, left optic nerve carries information from the right half of the field of vision, and vice versa
allows brain to deduce distances and sizes
visual cortex:
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receives point-by-point information about the visual field from optic nerves
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and interprets it into meaningful images
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by communicating with various areas of the brain,
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comparing input with stored memories
Label a diagram of the ear.
E.2.7 Sound perception
• How we perceive sound is a sequences of
changes of energy from one form to another.
Initially the incoming sound into the ear is in
the form of a pressure wave in air which will
ultimately be transformed into a nerve
impulse, which as we know is a wave of
sodium ions traveling down the axon.
E.3.1 Distinguish between innate and
learned behavior
E.3.2 Design experiments to
investigate innate behavior in
invertibrates
• Innate behaviors can be measured as the
animals respond to environmental stimuli
• Two basic kinds of movement are seen in
invertebrate animals:
– Taxis
– Kinesis
E.3.3 Analyse data from invertebrate
behavior
• Chemotaxis: response to chemicals in the environment;
experiments involving variation in pH, dissolved drugs,
food, pesticides
• Phototaxis: response to light; experiments involving
different wavelengths of light, intensities, and different
types of bulb
• Gravitaxis: response to gravity; experiments with organism
in container that is turned upside down or on a turntable
• Rheotaxis: response to water current; experiment
involving animals with and against current
• Thigmotaxis: response to touch; experiment involving
different types of material to touch an organism
E.3.4 Discuss how the process of
learning can improve the chance of
survival
• Learning occurs most easily when it results in
the animal’s survival
• Imprinting – process by which young animals
become attached to their mother within the
first day or so after hatching or birth; assures
that the young stay close to their mother for
protection and as a source of food
E.3.5 Outline Pavlov’s experiment
• Classical conditioning can be used to modify a reflex response
• Russian physiologist Ivan Pavlov designed experiments to illustrate
classical conditioning
• His subjects were dogs
• Salivation is a reflex response to the presence of food in the mouth
• Food is unconditional stimulus which elicits salivation which is
unconditional response
• Neutral stimulation that Pavlov employed was the ringing of a bell
• He rang the bell (conditioned stimulus) just before the dog tasted
the food
• After training, the could ring the bell (CS) and the dog would
salivate (conditioned result)
• Dog had learned to salivate to the neutral stimulus
E.3.6 Role of inheritance -birdsong
• After hatching, there is a memorization phase in which
the bird is silent but listening to the song of his species
from adults (males)
• He attempts to match his template to the full adult
song
• Phase if over within 100 days (sensitive period)
• 2nd phase is motor phase in which he practices singing,
continuing to listen to his own song and match it to his
father’s
• As he becomes sexually mature, his song will become
perfected and he will begin to search for a mate
• Crude template is innate; adult song is learned
E.4.1 State the presynaptic neurons
E.4.2 descision making in the CNS
• Neurones form synaptic
junctions with the cell body of
other neurones.
• A post synaptic neurone can
have many pre-synaptic
neurones forming synaptic
junctions with it.
• Pre synaptic neurones
depolarise (excitatory) or
hyperpolarise (inhibitory) the
post synaptic membrane
locally.
• The sum of their effects takes
place at the axon hillock
E.4.4 List three examples of excitatory and three examples of inhibitory
psychoactive drugs
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excitatory psychoactive drugs:
nicotine
cocaine
amphetamines
inhibitatory psychoactive drugs:
benzodiazepines
alcohol
tetrahydrocannabinol (THC)
E.4.5 Explain the effects of THC and cocaine in terms of their action at synapses
in the brain
• THC is an inhibitory psychoactive drug that decreases synaptic
transmission
– cannabinoid synapses involve post-synaptic neuronal release of endocannabanoid NTs
• endo-cannabanoids bind to cannabinoid receptors on pre-synaptic neurons
• modifying the pre-synaptic neuronal release of NTs
– THC binds to cannabinoid receptors
• inhibiting the release of neurotransmitters from the pre-synaptic neurons such as GABA
• the reduction in GABA frees dopaminergic synapses from inhibition
• leading to increase in dopamine release in the pleasure pathway
• cannabinoid receptors are found in various brain locations
– cerebellum
• THC thus impairs motor functions
– hippocampus
• THC thus impairs short-term memory functions
– cerebral cortex
• THC thus affects higher order thinking
E.4.6 Discuss the causes of addiction, including genetic predisposition,
social factors and dopamine secretion.
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genetic predisposition:
the tendency toward addiction is variable, with studies indicating that genetic factors have some influence
alcoholism, especially, tends to run in families
social factors:
a variety of social factors correlate positively with addiction:
– cultural traditions
– peer pressure
– poverty
– social deprivation
– traumatic life experiences
– mental health problems
dopamine secretion
many addictive drugs are excitatory at dopaminergic synapses, also known as the reward pathway
addiction is a result of dopaminergic synapses responding to regular use
– reduction in the number of dopamine receptors in post-synaptic neurons
– reduction in the release of dopamine from pre-synaptic neurons
tolerance to a drug
– a result of decreased number of receptors
– leading to increased dosage to produce the desired effect
withdrawl
– with reduction of receptors
– normal level of dopamine fails to produce pleasure
E.5.1 Label, on a diagram of the brain, the medulla oblongata,
cerebellum, hypothalamus, pituitary gland and cerebral hemisphere
E.5.2 Outline the functions for each of the parts of the human brain in.
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medulla oblongata: controls automatic and homeostatic activities, such as:
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cerebellum: coordinates unconscious functions, such as:
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regulates, appetite, thirst, body temperature, and sleep
secretes hormones of the posterior pituitary
secretes hormone releasing factors regulating the anterior pituitary
pituitary gland:
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body movements
posture and balance
hypothalamus: maintains homeostasis, coordinating the nervous and endocrine systems:
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swallowing
digestion & vomiting
breathing
heart activity
posterior lobe stores and releases hypothalamic hormones
anterior lobe produces, stores, and secretes many hormones regulating many body functions
cerebral hemispheres:
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act as integrating center for high complex functions, such as:
memory, learning, emotion, language, reasoning
E.5.3 Explain how animal experiments, lesions and fMRI (functional magnetic resonance
imaging) scanning can be used in the identification of the brain part involved in specific
functions, providing one specific example of each.
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animal experiments:
surgical procedures allow access to brain
experiments performed on live animals so that brain is functioning
effects of experiments observed during and/or after experiment
specific example: rats
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research into visual impairments such as strabismus (‘cross eye’)
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induced by covering the eye with material or stitching the eye shut
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monitor visual development
ethical issues related to suffering of animals, and sacrifice of animals
lesions:
damage to specific brain regions
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injury by accident/war
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stroke
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tumor
allow deduction of location of specific brain functions
specific example: stroke
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lesion in Broca's area in left cerebral hemisphere
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causes dysphasia, inability to speak
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but reading and writing are unaffected
fMRI
subject placed in scanning machine which measures blood flow to specific brain areas
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1st: high resolution
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2nd: series of low resolution while subject is given stimulus
specific example:
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subject view visual object moving across a screen and moves a cursor to track its movment
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fMRI indicates strong activation in cerebellum
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because cerebellum coordinates eye and hand movements
E.5.4 Explain sympathetic and parasympathetic control of the heart, movements of
the iris, and flow of blood to the gut.
• autonomic nervous system:
• sympathetic:
– fight-flight-excercise
• parasympathetic:
– restorative, resting, digesting
• heart
• sympathetic:
– heart rate accelerates, pumping more blood to muscles
• parasympathetic:
– heart rate slows, body relaxes, less blood needed to muscles
• blood flow to gut
• sympathetic:
– blood vessels constricted, decreasing blood flow to gut
• parasympathetic:
– blood vessels dilated, increasing blood flow to gut
5.5 Explain the pupil reflex.
• pupil reflex: when a bright light shines into one eye,
the pupils of both eyes normally constrict
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retina detects light intensity
impulses to brain in optic nerve
brain stem/medulla controls the reflex
sympathetic system causes dilation
parasympathetic system causes constriction
sympathetic neurons are in spinal nerve T1
parasympathetic neurons are in cranial nerve III
pre- and postganglionic fibers of symp/parasymp
neurotransmitters of symp/parasymp
polysynaptic reflex
Statement 5.6- Discuss the Use of the Pupil
Reflex in Testing for Brain Death
• If stimulation of the pupil with light fails to
cause contraction then it is very likely that the
CNS has sustained severe damage and brain
death is possible.
Statement 5.7- Outline How Pain is Sensed and
How Endorphins and Enkephalins can Act as
Painkillers.
Pain receptors are located in the skin and on organs. Pain signals are
sent along these nerve endings along nerve fibers on the spinal cord.
The signals pass synapses to neurons that carry them up in an
ascending tract to the stem or thalamus of the brain. The signals may
pass on in other neurons to sensory areas of the cerebral cortex,
causing conscious pain. --Endorphins and enkephalins act as
painkillers by stopping the pain signal to the brain. Enkephalins block
calcium channels in the membrane of the pre-synaptic neurons. They
block the synaptic transmissions, so the message doesn’t reach the
brain. Endorphins are released from the pituitary gland to control
pain. They are carried to the brain and bind to pain receptors and
block the release of the neurotransmitter that is used to transmit pain
signals to the brain.
Statement 6.1- Describe the Social Organization
of Honey Bee Colonies
There are three castes of honey bees which
have different tasks. The single queen bee of a
colony has to lay eggs. The worker bees do jobs
that maintain the colony. The drones do nothing
to help the colony to survive. However, if they
successfully mate with virgin queens, they
spread the genes of the colony to new colonies.
Workers eject drones from the colony at the
end of the season during which virgin queens
are available.
Statement 6.2- Outline How Natural Selection May Act at the
Level of the Colony in the Case of Social Organisms.
In the case of social animals, especially colonies, most of the individuals have very similar DNA so
their genes are still getting passed down even if they aren't themselves reproducing. So these
animals will sacrifice themselves for the greater good of their very close relatives.
I.E. prairie dogs on the lookout for predators will make a loud noise warning everyone to get in
their holes and by doing this he lets the predator know exactly where he is and will probably get
eaten but he has saved a lot of the colony.
Lions will give up trying to reproduce and just help their brother/nephew, whatever their
relationship is to the dominant male, get as many ladies as possible and protect his young.
From this evidence you can see that natural selection does not act on the population or the
individual, rather the genes
Statement 6.3- Discuss the Role of Altruistic
Behavior in Social Organizations Using Two
Examples
• Wolves - In a pack of wolves, there is a dominant
male and female which are the sole reproducers,
and the other members of the pack hunt and
bring back food for the breeding pair.
• Naked Mole Rats - There exist breeding males
and females, the diggers (who dig tunnels and
provide food) and protectors who offer their lives
when facing a predator. The concept is that the
sacrifices will indirectly pass on their genes by
protecting the mating pair.
Statement 6.4- Outline Two Examples of How Foraging Behavior
Optimizes Food Intake, Including Bluegill Fish Foraging for
Daphnia
Spirit Bear
• Spirit bears are omnivores whose diet includes plants, insects, living animals and
carcasses. During the salmon spawning season, spirit bears gorge themselves on
salmon because the salmon provide the maximum calorie supply. When salmon
are not available, 80% of their diet consists of plant material because meat is
harder to find.
• After catching a salmon spirit bears usually carry their fish away from the stream
where they can feed in seclusion. If the fish is a female they begin feeding on the
belly, which contains fat-rich eggs. They also feed on the brains and certain organs,
which are also fat-rich.
• The bear’s preference of feeding in seclusion reduces the chances of losing a meal
to a rival bear or wasting time fighting the rival. And their preference for high-fat
organs ensures that their bellies fill up with organs with the highest energy
content.
• The spirit bear’s food preferences match foraging theory. Over evolutionary time,
natural selection has favored bears that prefer fatty meat because they were able
to consume more calories than bears that ate less fatty meat. In bleak years, when
competition for food was fierce, bears eating fatty foods would have survived
better than individuals consuming lower energy food items.
Statement 6.4- Outline Two Examples of How Foraging Behavior
Optimizes Food Intake, Including Bluegill Fish Foraging for
Daphnia (cont.)
• When environmental conditions change, generalist feeders
have an advantage over specialist feeders because they can
adjust their feeding behavior to optimize their chances of
survival.
• A good example of this comes from studies on the bluegill
sunfish, which feeds on small invertebrates like Daphnia.
• When Daphnia is abundant the sunfish can afford to be
choosy, and as such they feed exclusively on larger prey
items. However, when prey is scarce they must eat
whatever food items they can find.
• The graphs indicate that average prey size increases as prey
density increases.
Statement 6.5- Explain How Mate Selection Can
Lead to Exaggerated Traits.
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Evolutionary success means successfully passing on your genes to future generations. In some species evolutionary success
has led to the evolution of differences between males and females, a phenomenon called sexual dimorphism.
In some species, males have evolved conspicuous or exagerated traits that advertise their reproductive worth. The
spectacularly colorful tail feathers of peacocks provide a good example of this.
Some studies suggest that peahens choose to have sex with the most colorful peacocks available, and that males with
parasites are less brightly colored. The researchers suggest that this color preference of peahens causes them to breed with
the strongest, healthiest and least-parasitized males.
However, more recent research has disputed a link between feather color and parasitism. These studies suggest that
peacocks select males with the loudest vocalizations. So it’s possible that a peacock's color does not indicate health. If this is
so then colorful peacock feathers could be an example ofrunaway evolution.
In runaway evolution one female develops a whim for a particular male trait that she then passes on to future generations of
females. These females start choosing males with the desired trait, which causes that trait to become exagerated in males
over time.
Thus runaway evolution can lead to to exaggerated traits that don’t really help the species as a whole. The peacock's tail, for
example, requires a great deal of energy to grow and maintain, it reduces the bird's agility, and it increases the animal’s
visibility to predators. Yet it has evolved, indicating that the advantage of having a longer tail, in terms of getting sex,
outweighs the disadvantages.
Statement 6.6- State That Animals Show
Rhythmical Variations in Activity
• Animals show a rhythmic variation in activity
as the year passes. Many different animals
show their rhythmic variation in the form of
hibernation when, annually, the animals
decrease in activity drastically during the
winter months of the year
Statement 6.7- Outline Two Examples Illustrating the
Adaptive Value of Rhythmical Behavior Patterns.
Krill
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Krill are shrimp-like marine invertebrates. They are important sources of food for certain whales, sharks,
seals and penguins.
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Krill typically follow a diurnal vertical migration. They spend the day at greater depths and rise during the
night towards the surface. The deeper they go, the darker the water becomes, and this makes it more
difficult for predators to eat them.
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The diurnal migrations of krill depend on accurate monitoring of daylight, which is achieved by their
circadian system.
Insect-eating Bats
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The circadian "clock" in mammals is located in a part of the hypothalamus called the SCN. The SCN
receives information about daylight from special photoreceptors in the retina.
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The SCN sends a message to the pineal gland, a tiny structure in the brain, which secretes the hormone
melatonin. Melatonin causes mammals to feel sleepy. In humans, secretion of melatonin peaks at night.
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In bats, melatonin peaks in the daytime, which is why they are more active at night? Being active at night
is a benefit to bats because they feed on moths, which mainly fly at night. Thus the circadian rhythm of
bats helps them to hunt and feed when their prey is most abundant.