Tuesday, April 15, 2014

Warm Up 4/14

1.     Describe, using an example, the role of altruistic behavior
§  Altruism is behaviour which benefits another individual at the cost of the performer
§  It appears to be in opposition to natural selection as it reduces the possibility of the altruistic individual passing on their own genes
§  However it improves the chances of the other individual passing on genes into the same gene pool (this is called inclusive fitness)
§  If the individuals are closely related, altruistic genes will persist in the gene pool and be naturally selected
§  Enhancing the reproductive success of relatives is called kin selection
§  Altruism occurs in social animals and is more common in members of the same species who are closely related

Examples of Altruism:
§  Vampire bats commonly regurgitate blood to share with unlucky or sick roost mates unable to gain independent sustenance
§  Velvet monkeys give alarm calls to warn fellow monkeys of predators, even though doing so draws attention to themselves
§  Termites break a gland in their neck, releasing a sticky substance which protects others from attacking ants at the cost of their life

2.     Explain how the sympathetic and parasympathetic systems control the heart, the salivary glands, and the iris of the eye
The sympathetic and parasympathetic nervous systems are part of the autonomic system and have antagonistic actions

Sympathetic Nervous System
§  Involved in processes that prepare the body for action ('fight or flight' responses)
§  The sympathetic nervous system releases noradrenaline (adrenergic) via sympathetic nerves
§  Heart rate will increase to improve blood flow (via release of adrenaline)
§  Pupils will dilate to improve vision (via contraction of radial muscles)
§  Blood flow to gut will decrease (due to vasoconstriction of blood vessels by smooth muscles)

Parasympathetic Nervous System
§  Involved in processes that occur when the body is relaxed ('rest and digest' or 'feed and breed' responses)
§  The parasympathetic nervous system releases acetylcholine (cholinergic) via parasympathetic nerves
§  Heart rate will decrease to reduce blood flow (via stimulation by vagus nerve)
§  Pupils will constrict to restrict light and potential retinal damage (via contraction of circular muscles)
§  Blood flow to gut will increase to facilitate digestion (due to vasodilation of blood vessels by smooth muscles)


3.     Outline how endorphins can act as painkillers
·       Pain is perceived when impulses pass from pain receptors (nocireceptors) in body tissues to sensory areas of the cerebral cortex
·       Endorphins are released by the pituitary gland during stress, injury or exercise and act as painkillers by blocking pain perception
·       They do this by blocking the release of neurotransmitters at the synapses involved in pain signal transmission

4.     Define the term innate behavior

·       Innate behaviour is an instinctive response that is developmentally fixed (i.e. independent of environmental context)