Animal responses Flashcards
Whats the autonomic nervous system
this is part of the nervous system responsible for controlling the involuntary motor activities of the body
Whats the peripheral nervous system
the sensory and motor nerves connecting the sensory receptors and effectors to the CNS
Whats the somatic nervous system
the motor neurones under conscious control
Whats the central nervous system
the central part of the nervous system composed of the brain and spinal cord
describe divisions of the nervous system
- there is the PNS and CNS
PNS - this further divides into the sensory and motor system
- motor system divides into the somatic nervous system and the autonomic nervous system
CNS - divides into the brain and spinal cord
Describe the CNS
- CNS consists of the brain and spinal cord
- much of the brain is composed of relay neurones which have multiple connections enabling complex neural pathways - these cells are non-myelinated cells and the tissue looks grey in colour and is known as grey matter
- spinal cord has many non-myelinated relay neurones making up central grey matter - spinal cord contains large numbers of myelinated neurones making up an outer region of white matter
- myelinated neurones carry action potentials up and down the spinal cord for rapid communication over longer distances
- spinal cord is protected by the vertebral column - between each of the vertebrae peripheral nerves enter and leave the spinal cord carrying action potentials to and from the rest of the body
What is the role of the peripheral nervous system
- role of the PNS is to ensure rapid communication between sensory receptors, the CNS and the effectors
- PNS is composed of sensory and motor neurones which are usually bundled together in connective tissue sheath to form nerves
describe the sensory nervous system
- sensory fibres entering the CNS are dendrons of the sensory neurones
- neurones conduct action potentials from the sensory receptors into the CNS
- these neurones have their cell body in the dorsal root leading into the spinal cord and a short axon connecting to other neurones in the CNS
Describe the motor nervous system - The somatic nervous system
- conducts action potentials from the CNS to the effectors
- the somatic nervous system - consists of motor neurones that conduct action potentials from the CNS to the effectors that are under voluntary control such as the skeletal muscles, these neurones are mostly myelinated so that response can be rapid - always one single motor neurone connecting the CNS to the effector
Describe the motor nervous system - The autonomic nervous system
- the autonomic nervous system - consists of motor neurones that conduct the action potentials from the CNS to effectors that are not under voluntary control this includes the glands, cardiac muscle and smooth muscle in the walls of the blood vessels, the airways and the wall of the digestive system
- the control of many of these effectors does not require rapid responses and the neurones are mostly non-myelinated
- there are at least two neurones involved in the connection between the CNS and the effector - they are connected at small swellings called ganglia
what can the autonomic system be divided in to
- sympathetic system and the parasympathetic system
Describe differences between the sympathetic system and the parasympathetic system
sympathetic system
- prepares body for activity
- antagonistic to the parasympathetic system
parasympathetic system
- conserves energy
- antagonistic to the sympathetic system
how they are similar
- action potential passes along at low frequency
- controlled by subconscious parts of the brain
- changes in internal conditions or stress lead to changes in the balance of stimulation between the two systems and this leads to an appropriate response
describe the role of the sympathetic system
- consists of many nerves leading out of the CNS
- ganglia just outside the CNS
- short pre-ganglionic neurones
- long post-ganglionic neurones
- uses noradrenaline as the neurotransmitter
- increases activity
- most active at times of stress
- effects include : increases heart rate, dilutes pupils, increases ventilation rate, reduces digestive activity, orgasm
describe the role of the parasympathetic system
- consists of a few nerves leading out of the CNS which divide up and lead to different effectors
- ganglia in the effector tissue
- long pre-ganglionic neurones
- short post-ganglionic neurones
- uses acetylcholine as the neurotransmitter
- decreases activity
- most active during relaxation
- effects include - decrease heart rate, constricts pupils, reduces ventilation rate, increases digestive activity, sexual arousal
What are the four main parts of the brain
- cerebrum
- cerebellum
- hypothalamus and pituitary complex
- medulla oblongata
Describe the role of them cerebrum
largest part and organises most of our higher thought processes such as conscious thought and memory
Describe the role of the cerebellum
coordinates movement and balance
Describe the role of the hypothalamus and pituitary complex
organises homeostatic responses and controls various physiological processes
Describe the role of the medulla oblongata
coordinates many autonomic responses
Describe the structure of the cerebrum
- 2 cerebral hemispheres that are connected by major tracts of neurones called the corpus callosum
- outermost layer of the cerebrum consists of a thin layer of nerve cell bodies called the cerebral cortex
Divided into areas:
- sensory areas
- association areas
- motor areas
what higher order brain functions does the cerebrum control
- conscious thought
- conscious action
- emotional responses
- intelligence, reasoning, judgement and decision making
- factual memory
what does the sensory area do in the cerebrum
- receive action potentials indirectly from the sensory receptors
- size and regions allocated to receive input from different receptors are related to the sensitivity of the area that inputs are received from
What does the association area do in the cerebrum
- compare sensory inputs with previous experience, interpret what the input mean and judge and appropriate response
What does the motor area do in the cerebrum
- send action potentials to various effectors
- sizes of the regions allocated to deal with different effectors are related to the complexity of the movements needed in the parts of the body
- motor areas of the left side of the brain control the effectors on the right and vis versa
Describe the structure of the cerebellum
- contains over half of all of the neurones in the brain
- involved with balance and fine coordination of movement
- it must receive information from many sensory receptors and process the information accurately
- sensory receptors that supply infomration to the cerebellum include the retina, the balance organs in the inner ear and spindle fibres in the muscle which give information about the muscle length and the joints
Describes jobs of the cerebellum
- maintaining body position and balance
- judging the position of objects and limbs while moving about or playing sport
- tensioning muscles in order to use tools and play musical instruments effectively
- coordinating contraction and relaxation of antagonisitc skeletal muscles when walking and running
Describe how the cerebellum does the jobs that it does
- control often requires learning
- once learnt they become second nature and involve much unconscious control
- this sort of coordination requires complex nervous pathways and these are strengthened by practise
- they become programmed into the cerebellum and neurones from the cerebellum conduct action potentials to the motor area so that motor output to the effectors are controlled
Describe the hypothalamus
- temperature - detects temperature changes in core body temperature, also receives sensory input from temperature receptors in the skin, it will initiate responses to temperature change that regulate body temperature within a narrow range - mediated by the nervous system or by the hormonal system
- osmoregulation - hypothalamus contains osmoreceptors that monitor the water potential in the blood - when the water potential changes the osmoregulatory centre initiates responses that bring about a reversal of this change - these are mediated by the hormonal system