5.5.6 the brain Flashcards
4 main parts of the brain
- cerebrum
- cerebellum
- hypothalamus & pituitary complex
- medulla oblongata
describe the structure of the cerebrum
- 2 cerebral hemispheres connected by corpus callosum
- outermost layer = thin layer of nerve cell bodies called the ‘cerebral cortex’
corpus callosum
major tracts of neurones connecting the 2 cerebral hemispheres
role of cerebrum
controls ‘higher brain’ functions, eg:
- conscious thought
- conscious actions
- emotional responses
- intelligence, reasoning, judgement & decision making
- factual memory
subdivisions of cerebral cortex
- sensory areas
- association areas
- motor areas
describe the sensory areas
- receive action potentials from sensory receptors
- sizes of regions allocated to receive input from different receptors related sensitivity of area input received from
describe association areas
- compare sensory inputs with previous experiences (schema)
- interpret what input means
- judge appropriate response
describe motor areas
- send action potentials to various effectors (muscles/glands)
- size of region allocated to deal with different effectors related to complexity of movement needed in parts of body
- left side: control effectors on right (vice versa)
roles of cerebellum
- involved with balance & fine coordination of movement
- receives info from many sensory receptors & processes information (eg. retina, balance organs in ear)
what decision is initiated in the cerebral cortex
to contract voluntary muscles
examples of fine muscular movements controlled by the cerebellum
- maintaining body position & balance (eg. riding a bike)
- judging position of objects & limbs when moving/playing a sport
- tensioning muscles to use tools & play musical instruments
- coordinating contraction & relaxation of antagonistic skeletal muscles when walking/running
what does fine control of muscular movements often require
= learning
- may become second nature & involve much unconscious control once learnt
- requires complex nervous pathways (strengthened by practice)
- complex activity becomes ‘programmed’ into cerebellum & neurones from cerebellum conduct action potential to motor areas (motor output to effectors is finely controlled)
what are the cerebrum & cerebellum connected by
the pons
what does the hypothalamus control
- homeostatic mechanisms in the body
- contains own sensory receptors
- acts by negative feedback to maintain constant internal environment
how does hypothalamus control temperature regulation
- detects change in core body temperature
- also receives sensory input from temperature receptors in skin
- initiates responses to temperature change to regulate temperature (narrow range)
- responses may be mediated by nervous system or hormonal system (via pituitary gland)
how is the hypothalamus involved in osmoregulation
- contains osmoreceptors which monitor water potential of blood
- when water potential changes, osmoregulatory centre initiates responses which bring about reversal of change
- responses mediated by hormonal system via pituitary gland
what does the pituitary gland consist of
2 lobes:
- posterior lobe
- anterior lobe
describe functions of posterior lobe of pituitary gland
- linked to hypothalamus by specialised neurosecretory cells
- hormones (eg. ADH) are manufactured in hypothalamus, pass down neurosecretory cells & released into blood from pituitary gland
describe functions of anterior lobe of pituitary gland
- produces own hormones
- hormones released into blood in response to releasing factors (produced by hypothalamus)
- releasing factors are hormones that need to be transported from hypothalamus to pituitary
- hormones from anterior pituitary control number of physiological processes (eg. stress response, growth, reproduction, lactation)
what does the medulla oblongata control
- controls non-skeletal muscles (cardiac muscles & involuntary smooth muscles) by sending action potentials out through autonomic nervous system
- contains centres for regulating several vital processes
- centres receive sensory information & coordinate vital functions by negative feedback
which centres does the medulla oblongata contrail for regulating several vital processes
- cardiac centre = regulates heart rate
- vasomotor centre = regulates circulation & blood pressure
- respiratory centre = controls rate & depth of breathing
