The Nervous System Flashcards
What are the different parts of the nervous system
The nervous system is made of the CNS central and PNS peripheral
The CNS includes the spinal cord and brain
The PNS contains the somatic and autonomic nervous
Autonomic nervous system is split into sympathetic and parasympathetic nervous system
What is the nervous system?
The nervous system is a specialised network of cells in the human body and is our primary internal communication system.
What are main functions in the nervous system?
- To collect, process and respond to information in the environment.
- To coordinate the working of different organs and cells in the body
What does the brain do and explain the structure?
• The brain is the 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. The brain is divided into two hemispheres – left and right.
Function of the spinal cord
• The spinal cord is an extension of the brain. It is responsible for reflex actions such as pulling your hand away from a hot plate. It passes messages to and from the brain and connects nerves to the PNS.
The main function of the spinal cord is to relay information between the brain and the rest of the body. This allows the brain to monitor and regulate bodily processes, such as digestion and breathing, and to coordinate voluntary movements. The 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.
What does the PNS do
The PNS transmits messages, via millions of neurons (nerve cells) to and from the CNS. The PNS is further is further sub-divided into the:
Explain autonomic nervous system
• Autonomic Nervous System (ANS) – which governs vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress responses
The ANS 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. The ANS has two parts: the sympathetic and parasympathetic. Both of these divisions tend to regulate the same organs but have but have opposite effects – mainly because of the 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.
To summarise, the autonomic nervous system plays an important role in homeostasis, which maintains internal processes like body temperature, heart rate and blood pressure. The autonomic nervous system only consists of motor pathways and has two components: 1) the sympathetic nervous system and 2) the parasympathetic nervous system.
Explain the somatic nervous system
• Somatic Nervous System (SNS) – this controls muscle movement and receives information from sensory receptors
The Somatic Nervous System is made up of 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 is also involved in reflex actions without the involvement of the CNS and allows the reflex to occur very quickly. The SNS control centres is in the motor cortex part of the brain.
To summarise, The somatic nervous system facilitates communication between the CNS and the outside world. The somatic nervous system is made up of sensory receptors that carry information to the spinal cord and brain, and motor pathways that allow the brain to control movement. Therefore, 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.
Explain the divisions of the brain
The billions of neurons in the brain can be divided into hundreds of separate structures. However, an outline of its major components brings this number down to a more manageable level, with an initial division into hindbrain, midbrain and forebrain
However, there are four main divisions of the brain:
Cerebrum cerebellum Diencephalonand brainstem
What is the cerebrum?
- The cerebrum is the largest part of the brain, and is further divided into four different lobes, each of which has a different primary function (the frontal lobe, temporal lobe, parietal lobe and occipital lobe). The cerebrum is also spilt into two halves called cerebral hemispheres – each hemisphere is specialised for particular behaviours and the two hemispheres communicate via the corpus callosum
What is the cerebellum?
- The cerebellum sits 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.
What is the diencephalon
- The diencephalon has a central location within the human brain sitting just above the brain stem. It is 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).
What is the brainstem?
- The brain stem is 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.
What is the sympathetic nervous system?
The sympathetic nervous system is involved in responses that helps us to deal with emergencies (fight/flight) such as increasing heart rate and blood pressure and dilating blood vessels in the muscles. Neurons from the sympathetic nervous system travel to almost every organ and gland within the body preparing the body for rapid action. For example, 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.
To summarise, the sympathetic nervous system is typically involved in responses that prepare the body for fight or flight. 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. For example, our heart rate, blood pressure and breathing rate increase, while less important functions like digestion, salivation and the desire to urinate are suppressed.
What is the person sympathetic nervous system?
If we think of the SNS as pushing the individual into action when faced with an emergency, then the parasympathetic nervous system (PNS) relaxes them again once the emergency has passed. For example, the PNS slows the heartbeat down and reduces blood pressure. Digestion begins again. Because the PNS is involved with energy conservation and digestion, it is sometimes referred to as the body’s rest and digest system.
To summarise, 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).
