L1 - The Nervous System Flashcards
1
Q
What is the nervous system?
A
- specialised network of cells in the human body and is our primary internal communication system. It has two main functions:
- To collect, process and respond to information in the environment.
- To coordinate the working of different organs and cells in the body
- communicates with outside world as well as internally
2
Q
The divisions of the nervous system
A
- Splits into central nervous system & peripheral nervous system
- Central nervous system consists of brain and spinal cord
- Peripheral nervous system consists of somatic and autonomic nervous system
- autonomic nervous system consists of sympathetic and parasympathetic nervous system
3
Q
Brain
A
- centre of all conscious awareness, The brain’s outer layer, the cerebral cortex, is highly developed in humans and is what distinguishes our higher mental functions from those of animals
- divided into two hemispheres – left and right
- initially divided into forebrain (front), midbrain (middle) & hindbrain (back)
- can be split into 4 main sections - cerebrum, cerebellum, diencephalon & brain stem
4
Q
Cerebrum
A
- largest part of the brain, further divided into four different lobes, each has a different primary function
- frontal lobe - thinking/language
- temporal lobe - understanding language
- parietal lobe - senses
- occipital lobe - sight
- also spilt into two halves called cerebral hemispheres – each hemisphere is specialised for particular behaviours and the two hemispheres communicate via the corpus callosum
5
Q
Cerebellum
A
- at the back of the cerebrum and is involved in controlling a person’s motor skills and balance, coordinating the muscles to allow precise movements
6
Q
Diencephalon
A
- central location within the human brain - just above the brain stem
- divided into four main structures - the thalamus, hypothalamus, epithalamus, and subthalamus
- The diencephalon is involved in many crucial bodily functions including coordinating with the endocrine system to release hormones, relaying sensory and motor signals to the cerebral cortex, and regulating circadian rhythms (the sleep wake cycle)
7
Q
Brain stem
A
- responsible for regulating automatic functions essential for living such as breathing, heartbeat and swallowing
- Also, motor and sensory neurons travel through the brain stem, allowing impulses to pass between the brain and the spinal cord
8
Q
Spinal chord
A
- The spinal cord is an extension of the brain
- passes messages to and from the brain and connects nerves to the PNS
- Main function is to relay information between the brain and the rest of the body - allows the brain to monitor and regulate bodily processes, such as digestion and breathing, and to coordinate voluntary movements
- spinal cord is connected to different parts of the body by pairs of spinal nerves, which connect the specific muscles and glands.
- The spinal cord also contains circuits of nerve cells that enable us to perform simple reflexes without the direct involvement of the brain, for example pulling your hand away from something that is hot.
9
Q
Somatic nervous system
A
- has 12 pairs of cranial nerves (nerves that emerge directly from the underside of the brain) and 31 pairs of spinal nerves (nerves from the spinal cord)
- These nerves have both sensory and motor neurons
- Sensory neurons send messages to the CNS via receptors and the CNS then relays these messages to motor neurons via effectors
- The SNS control centres is in the motor cortex part of the brain
- it facilitates communication between the CNS and the outside world
- made up of sensory receptors that carry information to the spinal cord and brain, and motor pathways that allow the brain to control movement
- the role of the somatic nervous system is to carry sensory information from the outside world to the brain and provide muscle responses via the motor pathways.
10
Q
Autonomic nervous system
A
- regulates involuntary actions such as heart beats, digesting food etc so is responsible for regulating automatic internal bodily responses
- The ANS control centre is in the brain stem
- has two parts: the sympathetic and parasympathetic. Both of these divisions tend to regulate the same organs but have but have opposite effects – due to neurotransmitters associated with both since the sympathetic division uses noradrenaline which has stimulating effects whereas as the parasympathetic division uses acetylcholine which has inhibiting effects
- plays an important role in homeostasis, which maintains internal processes like body temperature, heart rate and blood pressure.
- autonomic nervous system only consists of motor pathways and has the two components
11
Q
Sympathetic nervous system
A
- involved in responses that helps us to deal with emergencies (fight/flight)
E.g. increasing heart rate and blood pressure and dilating blood vessels in the muscles while less important functions like digestion, salivation and the desire to urinate are suppressed - Neurons from the sympathetic nervous system travel to almost every organ and gland within the body preparing the body for rapid action.
E.g. the sympathetic nervous system causes the body to release stored energy, pupils to dilate and inhibit digestion as well as your hair to stand on end. - Impulses travel from the sympathetic nervous system to organs in the body to help us prepare for action when we are faced with a dangerous situation - releases adrenaline
12
Q
Parasympathetic nervous system
A
- the parasympathetic nervous system (PNS) relaxes them again once the emergency has passed
- as the PNS is involved with energy conservation and digestion, it is sometimes referred to as the body’s rest and digest system
- the role of the parasympathetic nervous system is to relax the body, and return us to our ‘normal’ resting state.
- Consequently, the parasympathetic nervous system slows down our heart rate and breathing rate, and reduces our blood pressure. Furthermore, any functions that were previously slowed down during a fight or flight reaction are started again (e.g. digestion).
13
Q
Similarities between brain & spinal chord
A
- both control involuntary processes
- brain stem controls breathing
- spinal chord controls involuntary reflexes
14
Q
Differences between brain & spinal chord
A
- brain provides conscious awareness, allows for higher order thinking but the spinal cord allows for simple reflex responses
- brain consists of multiple regions responsible for different functions whereas the spinal cord has one main function
15
Q
Similarities between somatic & autonomic
A
- sympathetic nervous system (part of ANS) & somatic nervous system respond to external stimuli, sympathetic nervous system responds to it by preparing for fight or flight and the somatic respond by to external stimuli - by carrying info from sensory receptors to the spinal chord and brain
