E.6c Food, Sleep, Sex

Bluegill sunfish live in ponds and feed on small invertebrates. Their prey can be classified into small, medium and larger sizes. They have a low density of prey, which means they eat all possible prey sizes to simply attain enough food. A high density of prey means a larger prey to optimize energy intake per effort. A medium density of prey means an intermediate strategy, which means favoring larger prey over smaller.

Starlings parents feed crane fly larvae to young, which they collect from soil b probing. Each larva is held in the beak this allows for additional larvae becomes increasing inefficient. However, flying is energetically costly, so maximizing the number of larvae carried per journey is also favored. Therefore the maximum number of larvae carried is a function of the distance between the foraging area and the nest. If close to the nest, fewer larvae are carried per journey. If far from the nest, more larvae are carried per journey.

E.6b Reciprocal Altruism

reciprocal altruism = benefitting nonrelatives at cost to self, possibly self-sacrifice

Bluegill sunfish live in ponds and feed on small invertebrates. Their prey can be classified into small, medium and larger sizes. They have a low density of prey, which means they eat all possible prey sizes to simply attain enough food. A high density of prey means a larger prey to optimize energy intake per effort. A medium density of prey means an intermediate strategy, which means favoring larger prey over smaller.

Starlings parents feed crane fly larvae to young, which they collect from soil b probing. Each larva is held in the beak this allows for additional larvae becomes increasing inefficient. However, flying is energetically costly, so maximizing the number of larvae carried per journey is also favored. Therefore the maximum number of larvae carried is a function of the distance between the foraging area and the nest. If close to the nest, fewer larvae are carried per journey. If far from the nest, more larvae are carried per journey.

 

E.6a Kin Selection

Pain and painkillers

Pain receptors in the skin and other parts of the body area able to detect stimuli. The receptors are the nerve endings of sensory neurons and they send impulses to the CNS. When these impulses reach the sensory areas of the cerebral cortex the human body experience the sensation of pain. The body uses natural painkillers to block the feeling of pain. They bind to receptors in synapses in the pathways used in the perception of pain.

Social Organism and Altruism

Honeybees are known as social organism. They survive as a colony. They perform actions that are considered altruistic. Altruism is defined as actions that increase another individual’s lifetime number of offspring at a cost to one’s own survival and reproduction. True altruism seems to involve animals that are genetically related.

E.3b Learned Behavior

Taxis: tests the locomotion of an organism in a particular direction in response to an external stimulus. Planaria moves towards food, which is a positive chemotaxis. Euglena moves towards light, which is a positive phototaxis.

Kinesis: tests the movement (as opposed to growth) of an organism or a cell in response to a stimulus, such that rate depends on intensity, but not direction, of the stimulus. Example, woodlice move about less in optimum, humid,conditions, and more in unfavorable, dry conditions.

Pavlov’s experiment

This experiment is the classical conditioning in dog salivation in response to food paired with a ringing bell.

innate: unconditioned stimulus: US=smell of food –> unconditioned response: UR=salivation

experience: US=food + conditioned stimulus: CS=bell –> UR=salivation

generalization: CS=bell –> UR=salivation ( UR becomes CR)

conditioned response CS=bell –> CR=salivation

E.3a Innate Behavior

Innate behavior is shown in all normal members of a species despite any variation in environmental influences.

Learned behavior is the modification of behavior as a result of experience

 

Moths learn by classical conditioning

• moths vary in their ability to learn by classical conditioning
• moths that are better at learning by classical conditioning will better associate black and orange caterpillars with noxious taste, and avoid getting sick, increasing survival chances
• alleles allowing classical conditioning are passed on to offspring at a higher rate than alleles without classical conditioning ability
• thus, classical conditioning alleles accumulate
• and the trait becomes common in the population

Bears learn by trial and error/operant conditioning

• bears vary in their ability to learn by operant conditioning
• bears that experiment with various methods to catch salmon obtain more resources than those that don’t, increasing their survival chances
• alleles that lead them to attempt operant conditioning are passed on to their offspring at a higher rate than alleles without operant conitioning ability
• thus, operant conditioning alleles accumulate
• and the trait becomes common in the population

Goslings imprint on their mothers

• goslings vary in their ability to imprint
• goslings that are able to imprint on their mother, will avoid predators by remaining close to her, increasing their chances of survival
• alleles allowing imprinting are passed on to their offspring at a higher rate than alleles without imprinting ability
• thus, imprinting alleles accumulate
• and the trait becomes common in the population

E.1 Stimulus & Response

Stimulus is a change in either the internal or external environment that is detected by a receptor and elicits a response.

Response is a change in an organism, produced by a stimulus.

Reflex is a rapid, unconscious response to a stimulus.

 

Receptors are sensory cells or nerve endings of sensory neurons. They transduce an environmental stimulus into an action potential.

Sensory neurons receive messages from receptors across synapses from sensory cells or from nerve endings of sensory neurons.They transmit messages to CNS.

Relay neurons receive messages from sensory neurons across synapses. They transmit messages to moto neurons that cause an appropriate response.

Motor neurons receive messages from relay neurons across synapses and transmit messages to effector organs.

 

The effectors receive messages from moto neurons and produce a response (either muscles contract or relax, or glands secrete)

E.4b Neurotransmitters

depression

• is caused by deficiency of norepinephrine NE and/or serotonin ST
• psychoactive drugs can increase the levels of NE/ST at synapses
• increase in secretion of NE/ST from pre-synaptic neurons
• suppression of NE/ST deactivating enzymes at post-synaptic neurons
• inhibition of NE/ST uptake by pre-synaptic neurons
• elevate mood in normal people
• alleviate depression in the chronically depressed

schizophrenia

• caused by excess of dopamine (DA)
• psychoactive drugs can decrease the levels of DA at synapses
• suppression of DA production by pre-synaptic neurons
• increase in enzymatic deactivation of DA at post-synaptic neurons
• increase in DA uptake by pre-synaptic neurons
• most effective agents in treatment of schizophrenia
• marked increase in DA levels by overuse of amphetamines, cocaine can cause paranoid/schizoid behavior even in normal humans

E.4a Synapses

EPSPs: excitatory post-synaptic potentials

• post-synaptic neurons have receptor proteins specific to excitatory neurotransmitters
• binding neurotransmitter makes post-synaptic membrane permeable to Na+, which moves across post-synaptic membrane
• causing depolarization of the post-synaptic membrane
• enzymes catabolize neurotransmitters
  • monoamine oxidase catabolizes norepinephrine
  • acetylcholine esterase catabolizes acetylcholine
  • examples of excitatory neurotransmitters
    • epinephrine
    • dopamine
    • serotonin

IPSPs: inhibitory post-synaptic potentials

• post-synaptic neurons have receptor proteins specific to excitatory neurotransmitters
• that make the post-synaptic membrane less permeable to Na+
• or allow K+ to diffuse out of the post-synaptic membrane
• causing hyperpolarization of the post-synaptic membrane
  • enzymes catabolize neurotransmitters
  • examples of inhibitory neurotransmitters
    • glycine
    • gamma-aminobutyric acid (GABA)
    • acetylcholine

decision-making in the CNS

• synapses are the sites of decision-making
• a post-synaptic neuron’s membrane potential is the summation of input from pre-synaptic neurons
  • EPSPs depolarize post-synaptic neurons
  • IPSPs hyper-polarize post-synaptic neurons
• if the post-synaptic neuron reaches threshold potential at its axon hillock, it will produce an action potential
• pre-synaptic neurons can vary in the frequency, but not intensity of their input, since action potentials are “all-or-none”

 

E.5b Brain Function

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

iris of the eye

• sympathetic:
  • radial muscles contract, dilating the pupil to receive more light
• parasympathetic:
  • circular muscle fibers contract, pupil constricts, protecting retina from too much light

 

pupil reflex: when a bright light shines into one eye, the pupils of both eyes normally constrict

• 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

E.5a Brain Structure

• Medulla oblongata controls automatic and homeostatic activities, such as swallowing, digestion, vomiting, breathing and heart activity. 
• Cerebellum co-ordinates unconscious function, such as movement and balance.
• Hypothalamus maintains homeostasis, co-ordinating the nervous and endocrine systems, synthesizing the hormones secreted by the posterior pituitary, and releasing factors that regulate the secretion of hormones by the anterior pituitary.
• Pituitary gland the posterior lobe stores and releases hormones produced by the hypothalamus and the anterior lobe produces and secretes hormones that regulate many body functions.
• Cerebral hemispheres act as the integrating centre for high complex functions such as learning, memory and emotions.