Unit 3/Part 1: The Human Nervous System Flashcards
Explain and describe a neuron.
A neuron is an individual nerve cell. Neurons form connections with one another (pathways) to enable communication within the nervous system. There are many types of neurons and variations in shape and size, however there are common parts and functions. When a pre-synaptic neuron transfers information via electrical impulse down the axon which is then transferred to the post-synaptic neuron via chemical energy from neurotransmitters this is known as synaptic transmission.
Neurons are made up of 6 key components:
- dendrites: branches that receive information from previous neuron.
- soma (cell body): keeps neurons healthy and functioning.
- axon: transmits messages to end of neuron.
- myelin sheath: fatty covering over axon that is protective and speeds transmission.
- axon terminals and buttons: hold and release neurotransmitters.
- synapse (synaptic cleft): junction between two neurons, neurotransmitters pass over.
Explain the divisions in the nervous system.
The nervous system divides into the central nervous system and the peripheral nervous system. The central nervous system has two components; the spinal cord and the brain. The peripheral nervous system also has two components; the somatic nervous system and the autonomic nervous system. The autonomic nervous systems has its own divisions also and they are the sympathetic nervous system and the parasympathetic nervous system.
Describe the central nervous system.
The central nervous system comprises of the brain and spinal cord and its two main functions are to receive and process sensory information received from the peripheral nervous system and to initiate and send motor messages to the peripheral nervous system.
Describe the peripheral nervous system.
The peripheral nervous system comprises all parts of the nervous system outside the CNS (brain and spinal cord). Its two main functions are to send sensory information to the CNS, receive motor messages from the CNS and carry out movement and actions.
Describe the somatic nervous system.
The somatic nervous system is a division of the peripheral nervous system and its two main functions are to receive motor messages from the CNS to control skeletal muscles - voluntary, then send sensory information from the body to the CNS e.g. Touch and temperature on skin, moving hand when writing, controlling finger and hand movements to write.
Describe the autonomic nervous system.
The autonomic nervous system is a division of the peripheral nervous system and its main function is to self-regulate and control internal muscles, organs and glands essential to bodily function. *Remember IMOG - autonomic is non-skeletal
Internal muscles e.g. Bladder, stomach
Glands e.g. Adrenal gland
Organs e.g. Heart
Some functions such as breathing and blinking can be brought under voluntary control.
Describe the sympathetic nervous system.
Sympathetic nervous system is a division of the ANS and is activated in times of arousal (stress,fear,high physical activity). It increases the activity of many muscles, organs and glands to provide energy to face or flee the threat (fight or flight response) e.g. Increases heart rate, breathing and adrenalin levels for energy. It also decreases digestive activity, stimulation of the salivary glands and relaxes the bladder to conserve energy.
Describe the parasympathetic nervous system.
The parasympathetic nervous system is a division of the ANS is dominant in everyday functioning and maintains homeostasis (balance in body). It regulates activity of internal muscles, organs and glands e.g. Heart rate and breathing. It also increases and resumes normal functioning of the digestive system.
Explain the fight or flight response.
An adaptive response that activates the sympathetic nervous system to face or flee the threat.
Explain the nervous system.
The nervous system is the communications network that connects the brain to the rest of the body. The body sends sensory information (e.g. Sight, touch) to the brain for processing. The brain then sends motor information (movement and response) messages to the body. The nervous system is made up of billions of individual nerve cells called neurons.
What is the cerebral cortex?
The cerebral cortex is the convoluted (wrinkly) outer covering of the brain (forebrain). It’s between 2-5mm thick and its convoluted so as to increase surface area and fit a larger amount into the skull. The cerebral cortex is divided into hemispheres (halves) and the bundle of nerve fibres between those hemispheres that transfer messages is known as the corpus callosum. The convolutions (the many folds, grooves and bulges) make the surface area of the cortex large enough to contain an enormous number of neurons and blood vessels that can supply energy.
What is the cerebral cortex’s main functions?
It’s main functions are to receive and process sensory information, control voluntary skeletal movement, higher order mental skills such as planning, language, regulating emotions and creativity. The left hemisphere of the brain controls the right side of the body whereas the right hemisphere of the brain controls the left side of the body.
Explain the lobes of the cerebral cortex.
Each hemisphere of the cerebral cortex can be divided into 4 areas known as lobes. The division of lobes is based on location and function. The four lobes are the frontal lobe, parietal lobe, occipital lobe and the temporal lobe. Remember FPOT. Each lobe is made up of a primary cortex area and association area.
Describe the frontal lobe.
The frontal lobe is located at the front of the brain and its main functions include initiating movement of the body (motor functions), language, social skills, emotions, cognitive processes such as planning, judgment, problem solving and aspects of personality. The frontal lobe’s primary cortex is known as the primary motor cortex. It receives sensory information from the other lobes and then initiates movement (motor response).
Explain the primary motor cortex.
The primary motor cortex is situated at the rear of each frontal lobe, adjacent to the central fissure. It’s the part of the frontal lobe that’s responsible for movement of the skeletal muscles of the body and it works contra-laterally.
What are the bulges and valleys of the cerebral cortex known as?
The bulges are known as gyri (singular: gyrus) and the valleys are called sulci (singular: sulcus).
Explain the fissure of the cerebral cortex.
The central fissure is the deep groove that runs from the top and down the sides, which separates the front (anterior) of the cortex from the rear (posterior) section.
Explain the primary cortices.
When the senses first receive information from the environment, the information is sent to the thalamus, which then sends it to the primary cortex of the relevant lobe. It then begins processing and interpreting incoming sensory information. For example, the primary visual cortex in the occipital lobe receives visual information from the eyes, the primary auditory cortex in the temporal lobe receives sound information from the ears and the somatosensory cortex in the parietal lobe receives information from sense receptors in the skin.
Describe the parietal lobe.
The parietal lobe is situated behind the frontal lobe, so in the middle of the brain. It’s main function is to receive and process sensory information from the skin and body. It also is responsible for interpreting our own body’s position in space - a mental map.
Explain the primary somatosensory cortex.
The primary somatosensory cortex is situated at the front of the parietal lobe, adjacent to the central fissure. It is part of the parietal lobe that is responsible for processing sensation such as touch, pressure, temperature and pain from the body. Like the primary motor cortex of the frontal lobe, it functions contra-laterally. The left primary somatosensory cortex is responsible for processing sensation in the right-hand side of the body and vice versa.
Describe the temporal lobe.
The temporal lobe is situated beneath the frontal, parietal and occipital lobes and is mainly responsible for processing auditory information, which is sensations received from the ears. The temporal lobe performs the complex auditory analysis that is necessary for understanding human speech or listening to music. Parts of the lobe are specialised in sensitivity to particular types of sounds.
Explain the primary auditory cortex.
The primary auditory cortex is situated in the upper part of the temporal lobe and it’s main function is to process sound along with volume and pitch. The location of the sound is also processed via the primary auditory cortex.
Describe the occipital lobe.
The occipital lobe is entirely concerned with vision. Information from the left side of each retina is processed in the left occipital lobe and information from the right side of each retina is processed in the right occipital lobe.
Explain the primary visual cortex.
The primary visual cortex is located at the back of the occipital lobe and it’s main function is to process different types of visual stimuli, which the association areas organised into more complex forms to enable interpretation (perception).
