(Completed) Localisation and Function of the Brain Flashcards
The Human Nervous System:
Recall structure of human nervous system and role of each part
Central Nervous System (CNS) - to communicate information from the brain to the rest of the body by sending messages to the peripheral nervous system
Brain - responsible for intelligence and interpretation of the world around us. It controls muscles and behaviours, coordinates sensation and motor activity, stores memories, generates thoughts and emotions, source of our personality
Spinal Cord - conducts signals to and from brain, controls reflex activities
Peripheral Nervous System (PNS) - communicate information from body (sensory neurons) to CNS; comprised of all neural pathways outside of CNS
Somatic Nervous System - controls voluntary movement (skeletal muscles - striated); movements occurs via motor neurons which communicate information from CNS to muscles; transmits sensory information to CNS
Autonomic Nervous System - controls non voluntary action; some can be voluntarily influenced (voluntary-instigated); responsible for communicating between CNS and non-skeletal muscles (smooth muscles)
Sympathetic Nervous System - prepares body for action; arouses body to expend energy; fight or flight responses
Parasympathetic Nervous System - calms body to conserve and maintain energy; homeostasis (keeping systems in equilibrium); rest and digest responses
The Cerebral Cortex:
List and describe the major regions of the brain
The brain can be divided into three basic units:
Cerebrum
Forebrain (main focus): receives and processes sensory information, higher order thinking, planning, memory, language and emotions
Midbrain: Coordinates movement, sleep and arousal
Cerebellum
Hindbrain - links the spinal cord to the rest of the brain; responsible for coordinated muscle movements, posture and balance
Brain Stem - Medulla
Controls involuntary functions and actions such as breathing, heart rate, bodt temperature, sleep cycles and digestion. Also transmits information from cerebrum and cerebellum to rest of body
The Cerebral Cortex:
Identify the discrete areas (lobes) of the cerebral cortex and and describe their functions. If a lobe was damaged, what might the symptoms be?
Frontal Lobe: Largest of the lobes. Location of primary motor cortex. Has several functions including initiating body movement, language, planning, judgement, problem solving and aspects of personality and emotion. People with frontal lobe damage may be unable to learn new things, experience poor planning and/or some loss of some motor control.
Occipital Lobe: Entirely concerned with vision. Location of the primary visual cortex. Responsible for processing visual stimuli (e.g. visual mapping, colour, size, distance, depth), face and object recognition. Damage to this lobe generally causes lack of sight, difficulty recognises colours, shapes, faces and objects.
Parietal Lobe: Location of the somatosensory cortex (receives sensory information from the skin). Responsible for receiving information on sensation (touch, pressure, pain, temperature), and body spatial awareness (i.e. ability to perceive your own body and where things are located to you). Damage to this area leads to an inability to process sensation or that part of your body feeling numb.
Temporal Lobe: Location of the primary auditory cortex. Parts of the lobe are sensitive to specific sounds. Responsible for auditory analysis (e.g. understanding sounds, music, speech, sound location etc.). Damage to this area generally results in forms of deafness.
Human Nervous System:
Deacribe the role of the spinal cord in the nervous system with reference to spinal reflex.
The spinal cord connects the peripheral nervous system to the brain. Neurons and nerve bundles attach to different sections of the spinal cord. Damage to spinal cord can affect basic survival mechanisms controlled by spine
Neurons receive, process and transmit sensory information and motor commands, allowing our bodies to respond to internal and external environments.
Responses can be conscious (involving somatic nervous system) or unconscious (involving autonomic nervous system or reflexes).
A reflex is a fast, automatic, unplanned sequence of actions that occurs in response to a particular stimulus to enhance safety and chances of survival (e.g. pulling hand away from hot stove)
The reflex arc is the neural pathway followed by a reflex action.
Spinal Reflex:
What is a spinal reflex, what is it’s purpose, and what are the two types of spinal reflex.
Spinal reflex is when the reflex arc occurs completely within the spinal cord without involving the brain or conscious thought
Spinal reflex allows an organism to respond faster, which enhances safety and survival
Spinal Reflex:
What are the two types of spinal reflexes?
(1) Monosynaptic Reflex Arc: involving only one synapse, where an affecter neuron brings a sensation from receptors in the body and an effector neuron carries motor messages to the muscles of the body
(2) Polysynaptic Reflex Arc: involving interneurons connecting the affector and effector neurons, and, therefore, at least two synapses
Spinal Reflex:
Describe the neurons that form the spinal reflex arc and the progression/components of spinal reflex arc response in reference to these neurons
Sensory neurons - carry sensory information from the body and external environment to the CNS. Generally very long cells.
Interneurons - neurons that transmit between motor and sensory neurons; found only in the CNS. They are multipolar.
Motor neurons - communicate messages from the CNS to the muscle the organism intends to move
Process
1. Receptor - a special tansducer that registers the stimulus and transfers it to a chemical response
2. Sensory afferent neurons - transmits electrical response from the receptor to the spinal cord (CNS)
3. Integration center - (interneuron) transfers electrical impulses to lower motion
4. Motor (efferent) neuron - sends information to an effector
5. Effectors (muscle or gland activates) - perform action
OR
Receptor cells detect stimulus; sensory neuron receives message; transmission along sensory (afferent) pathway to spinal cord; sensory message received in spinal cord; interneuron relays message to motor neuron; transmission along motor (efferent) pathway to body part; motor message received in body part; spinal reflex involving withdrawal. After sensory message is received in spinal cord, message is also carried to brain; brain receives and interprets sensory message; pain perception.
Language Association Areas:
Recall the location and role of Broca’s Area, Wernicke’s Area, and Geschwind’s Territory.
Broca’s Area:
- middle to the left, back of the forebrain
- speech production
Wernicke’s Area:
- central but down slightly, lower half of midbrain
- understanding speech
Geschwind’s Territory:
- link of nerve fibres between/connecting Broca and Wernicke’s area but skewed towards the back of the brain
- Multimodal processing (i.e. how words sound, how words look and what they represent)
- enables the brain to interpret and classify things
Language Association Areas: What is aphasia? What are the characteristics of Broca and Wernicke’s aphasia?
Aphasia is an impairment of language, usually caused by left hemisphere damage either to Broca’s Area (impaired speaking) or to Wernicke’s area (impaired understnading)
Broca’s Aphasia:
- Occurs dues to damage in Broca’s area (left frontal lobe)
- Individual has difficulty finding words (expressing oneself via spoken means) however understanding of language/writing mostly unaffected
- characterised by non-fluent speech (broken, long pauses, 1-2 words at a time, mispronounced), articulation difficult, speech requires much effort (slow and deliberate), speech lacks grammar, writing difficult
- e.g. “Yes… Monday… Dad and John… Wednesday nine o’ clock”
Wernicke’s Aphasia:
- Occurs due to damage to Wernicke’s Area (left temporal lobe, near parietal cortex)
- Results in individual having difficulty producing written and spoken language that makes sense to others, with effects to understanding language/writing
- Characterised by fluent unbroken speech that is nonsensical, sounds like gibberish
- e.g. “Mother is away here working her work to get her better, but when she’s looking the two boys looking in the other part, she’s working another time”
Voluntary Movement:
Define voluntary movement and it’s uses? Describe how voluntary movement is initiated?
Voluntary movement is the conscious movement and control of body parts to visually explore the world, control facial expressions, to communicate etc.
To initiate voluntary motion, brain needs to gather and analyze information, plan and execute movement
E.g. the body’s current position (parietal lobe), movement goal (e.g. pick up cup), planning and choosing required muscles/movements (frontal lobe), memories of previous actions and their success (cerebellum) and execution (primary motor cortex)
The Role of Neurons in Communication:
Explain the process of neurotransmission
The neural message (action potential) is carried along the axon of a presynaptic neuron in electrical form to the terminal button
This signals the vesicles to release neurotransmitter molecules into synapses gap
Neurotransmitter molecules pass across the synaptic gap onto the surface of the dendrite of the postsynaptic neuron
If the structure of the neurotransmitter matches the receptor site on the dendrite of the postsynaptic neuron it will bind with the receptor site
Depending on the type of neurotransmitter released, this signals the postsynaptic neuron to excite (perform its function) or inhibit (block activation)
Excess neurotransmitter not used is reabsorbed back into the presynaptic neuron in process called reuptake
The Role of Neurons in Communication:
What are neurotransmitters and explain the process of neurotransmission at synapse
- Neurotransmitters are the chemical messengers of neurons as released by neurons in synaptic transmissions
- Over 100 different types of neurotransmitters
- Process: (1) Presynaptic neuron fires, (2) Synaptic vesicles move toward presynaptic membrane, (3) some synaptic vesicles stick to membrane,, break open and release neurotransmitter into synaptic cleft, (4), neurotransmitter bind with protein molecules - known as “receptors” - located on dendrites of the post synaptic neuron, (5) Receptors act like LOCKS - only opened by particular key or transmitter, (6) When receptor binds with the neurotransmitter that “fits” the post-synaptic neuron is either activated or inhibited
Probably Necessary Background; will have to draw a diagram:
List and define the structures of a neuron
Dendrites: hundreds or thousands of branches coming off soma. The dendrites receive information from other neurons, which they carry from synapse to soma.
Soma: The largest part of the neuron; the cell body. It controls metabolism and maintenance of the neuron. In most neurons, the soma receives messages from other neurons
Axon: The nerve fibre that extends from the soma and carries information towards the cells that communicate with that neuron.
Myelin: a coating of cells that covers the axon of most neurons that facilitates the transmission of information to other neurons. Myelin protects the axon from potential chemical and physical interference to the electrical impulses that travel along it. The insulation provides by the myelin sheath enables information to travel much faster (up to 400kph)
Axon Terminals: found at the end of the axon branch and function to transmit messages to the neuron. Axon terminals have terminal buttons which have sacs that secrete neurotransmitters whenever electrical impulses are sent down the axon. Axon terminals of one neuron link with the dendrites of the next neuron.
Types of Neurotransmitters:
Define and explain excitatory and inhibitory neurotransmitters, as well as action potential
Excitatory - causes the neurons to fire.
Inhibitory - inhibit the neuron from firing
Action potential - a momentary change in the electrical potential of a cell, which allows a nerve cell to transmit a signal or impulse towards another nerve cell (a threshold that must be reached in order for neurons to fire)
When an axon of a neuron fires the terminal buttons of the excitatory synapses release a neurotransmitter that excites the post synaptic neuron or causes it to reach its action potential. This excitement increases the amount of firing by postsynaptic neuron. In contrast, when inhibitory neurotransmitters are activated, the firing is reduced or stopped altogether. The excitation or inhibition effects produced only last a fraction of a second.
Types of Neurotransmitters:
Explain Glutamate and GABA and their roles as excitatory or inhibitory neurotransmitters
Glutamate - can excite almost every neuron in the brain and the rest of the nervous system (one of its main purposes). Involved in many psychological processes (particularly in learning and memory). Necessary for the changes in synapses that occur with memory formation.
GABA (gamma-amino butyric acid) - the main inhibitory neurotransmitter that calms nervous activity. Approx 1/3 of all neurons in brain use gamma (important for reducing anxiety). Responds to acohol and benzodiazepines.
