Week 2 - Structure of the brain Flashcards
What are the components of the Central Nervous System?
- The brain
- The spinal cord
What is the Peripheral Nervous System?
The part of the nervous system that consists of nerves that are located outside of the brain and spinal cord
What are afferent neurons?
Nerves that carry information from the peripheral nervous system to the spinal cord and brain
What are efferent neurons?
Nerves that carry information from the spinal cord and brain to the peripheral nervous system
What are sensory neurons?
A type of afferent neuron that carries information about the internal and external environment from the PNS to the CNS
Are sensory neurons afferent or efferent?
Afferent
Are motor neurons afferent or efferent?
Efferent
What are motor neurons?
Neurons that carry information from the brain to the muscles to initiate movement
What are the two main subdivisions of the Peripheral Nervous System?
- Autonomic nervous system
- Somatic nervous system
What is the autonomic nervous system?
The part of the nervous system which controls activities of the body that are outside of conscious control, eg heart rate and digestion of food
What are the two components of the autonomic nervous system?
- Sympathetic nervous system
- Parasympathetic nervous system
What is the sympathetic nervous system?
The part of the autonomic nervous system which controls “fight or flight” responses
What is the parasympathetic nervous system?
The part of the autonomic nervous system which deals with “rest and digest”
What is the sensory nervous system?
The system which is responsible for sensory neurons communicating information from the sense organs to the brain
What is the motor nervous system?
The system which deals with neurons which are responsible for the voluntary control of movement
What are the general characteristics of a stress response?
- Increase in heart rate
- Increase in breathing (lungs dilate)
- Decrease in digestive activity
- Liver releases glucose for energy
What are neurotransmitters?
Chemicals released by neurons which have effects on neighbouring cells
What are the 3 types of cells that neurotransmitters affect?
- Neurons
- Endocrine cells
- Muscle cells
What are receptors?
Proteins on or within a cell which respond to a biological molecule such as a neurotransmitter
What is noradrenalin?
A neurotransmitter which is primarily used within the sympathetic branch of the autonomic nervous system to transmit information to effector cells
What is noradrenalin also known as?
Norepinephrine
What type of cells does noradrenalin affect?
Effector cells
Within which branch of the autonomic nervous system is noradrenlin primarily used?
The sympathetic branch
Along with the sympathetic nervous system, what is the other component of a stress response?
The neuroendocrine system
What is the neuroendocrine system?
The system which comprises the hypothalamus and glands and controls hormone levels in the blood
What does the neuroendocrine system control?
Hormone levels in the blood
What is the function of hormones?
To regulate the activity level of cells and tissues
What is the difference between a hormone and a neurotransmitter?
- A hormone is a chemical which is released from a gland into the blood and circulates around the body
- A neurotransmitter is a chemical which is released from neurons to act directly on their target cell/organ
What areas of the brain does the neuroendocrine system consist of?
- Hypothalamus
- Pituitary gland
- Adrenal gland
What is a stressor?
Any stimulus which triggers a stress response
What is the hypothalamus?
The brain structure which is responsible for the control of many bodily functions
Which additional brain structure does the hypothalamus link to and why?
- The pituitary gland
- To modulate the release of hormones
Where in the body is the adrenal gland?
Just above the kidney
During the stress response is noradrenaline functioning as a neurotransmitter or a hormone?
Noradrenaline functions as both a hormone and a neurotransmitter
What is the feature of the stress response which ensures that cortisol levels in the blood do not rise indefinitely?
Negative feedback loops act on the hypothalamus and pituitary gland to dampen their activity
What is the third branch of the autonomic nervous system?
The enteric nervous system (ENS)
Why is the enteric nervous system different from the other parts of the peripheral nervous system?
There are some reflexes which operate entirely within the gut, without any input from the CNS
What is the gut-brain axis?
Biodirectional communication between the brain and the GI system involving the immune system, neurons and the neuroendocrine system
What are the components of the gut-brain axis?
- Vagus nerve
- Neuroendocrine system
- Immune system
At the simplest level, what are the three components of the brain?
- Cerebrum
- Cerebellum
- Brain stem
Which area of the brain is the largest?
The cerebrum
What regions of the brain are contained within the cerebrum?
- Cerebral cortex
- Subcortical regions
What are the functions of the cerebellum?
- Control of balance
- Movement
Where is the cerebellum located?
To the back of, and below, the cerebrum
Where is the brain stem located?
Below the cerebrum
What is the brain stem responsible for?
Control of involuntary processes, e.g. heart rate and breathing
What is the frontal lobe responsible for?
- Controlling movement and language
- Higher level cognitive skills such as reasoning and reasoning and planning
What is the parietal lobe responsible for?
- Processing information about touch
- Spatial awareness
What is the occipital lobe resonsible for?
- Processing of visual information
What is the temporal lobe responsible for?
- Processing auditory information
- Speech
- Memory
Which part of your brain would be responsible for deciding how to respond to the sound of a smoke alarm?
Frontal lobe
Which part of the brain is responsible for ascertaining the position of body parts in relation to one another, and using that information to guide movement?
Parietal lobe
Which part of the brain is responsible for processing visual information in order to move away from an area of danger?
Occipital lobe
Which part of the brain is responsible for processing the sound of a smoke alarm?
Temporal lobe
Which area of the brain is the largest?
Cerebrum
Which part of the brain is responsible for the complex higher order processing?
Cerebrum
Which area of the brain is responsible for the control of balance and movement?
Cerebellum
Where is the brain stem located?
Where the spinal cord joins the brain
Which part of the brain controls reflexes?
Brain stem
What are gyri?
The ridges on the surface of the cortex of the brain
What is the purpose of gyri?
To increase the surface area of the brain, which allows billions of cells to be contained in a relatively small space
What are sulci?
The grooves between the gyri
What is the purpose of the sulci?
To provide brain landmarks
Which area of the brain is involved in reasoning, movement and language?
Frontal lobe
Which area of the brain deals with processing touch information and spatial awareness?
Parietal lobe
What information does the occipital lobe process?
Visual information
Memory, understanding speech, and hearing are dealt with by which area of the brain?
Temporal lobe
What is the prefrontal cortex important for?
- Reasoning
- Moderating behaviour
- Planning
- Decision making
Planning and execution of voluntary movement is dealt with by which area of the brain?
Motor cortex
What is the primary somatosensory cortex?
The area of the brain which deals with processing information regarding touch, pain, temperature and body position from the sense organs
Information from the visual system is dealt with by which area of the brain?
Primary visual cortex
Information about sounds are dealt with where in the brain?
Primary auditory cortex
Where is the prefrontal cortex located within the brain?
The most anterior part of the frontal lobe
What is a coronal cut?
A vertical cut from the top of the brain to the bottom
What does a coronal cut do?
Divides the brain into a front and back portion
Which subdivision of the frontal lobe is important for executive function such as planning complex behaviour, decision-making and moderating behaviour?
Prefrontal cortex
Where is the orbitofrontal cortex situated within the brain?
At the very front
What is the orbitofrontal cortex important for?
- Reward
- Emotions
Touch and spatial awareness are dealt with by which part of the brain?
Parietal lobe
What type of information is processed by the occipital lobe?
Visual
What is the temporal lobe also sometimes called?
Temporal cortex
Memory, hearing and understanding speech is dealt with in which part of the brain?
Temporal lobe
The release of certain types of hormones into the blood is dealt with in which part of the brain?
Pituitary gland
The cerebellum is responsible for the control of what?
Movement
Using medical terminology, what position is the top of the brain described as being in?
The dorsal or superior direction
Using medical terminology, what position is the bottom of the brain described as being in?
The ventral or inferior direction
What is the position of the parietal lobe in relation to the temporal lobe?
Dorsal or superior to the temporal lobe
What direction is the front of the brain said to be in?
The rostral or anterior direction
What direction is the back of the brain said to be in?
The caudal or posterior direction
The term ‘lateral’ is used to describe the position of structures of which surface of the brain?
Structures towards the outer surface
The term ‘medial’ is used to describe the position of structures of which surface of the brain?
Structures towards the centre of the brain
If you cut down the centre of brain from front to back what type of cut would that be described as?
A saggital cut
Resolving conflict and dealing with emotions happens in which part of the brain?
The cingulate cortex
When is the cingulate cortex activated generally?
When a person cannot decide a course of action
What is the part of the cingulate cortex located near the front of the brain called?
The anterior cingulate cortex
What are the foldings of the cerebellum known as?
Folia
What is the corpus callosum?
A large bundle of neurons that cross the brain from one side to the other
Why is the corpus callosum a whitish colour?
Because it is covered in myelin
What is the purpose of myelin?
To speed up the passage of electrical information
Where in the brain are the ventricles located?
Underneath the corpus callosum
How many ventricles are there in the brain?
Four
What is the purpose of cerebrospinal fluid (CSF)?
To supply the brain with nutrients and remove waste products
Which regions of the brain are part of the collection of regions known as the basal ganglia?
- Caudate nucleus
- Putamen
What do the regions of the brain known as the basal ganglia control?
Movement
What is the hippocampus important for?
- Organisation and retrieval of memories
- Spatial memory and navigation
What type of structure is the hippocampus described as being?
A medial temporal lobe structure
Why is the hippocampus named so?
It comes from the Latin word for “seahorse” as its shape is similar to one
The hippocampus and which other region of the brain form the medial temporal lobe memory system?
The amygdala
Behaviour and emotions, especially the retrieval of unpleasant memories, are controlled by which brain region?
The amygdala
Which region of the brain is known as the relay centre?
The thalamus
Much of the sensory information from the body is rooted through which region of the brain?
The thalamus
What is the thalamus sometimes referred to as?
The gateway of the mind
What does hypo mean?
Below
Where is the hypothalamus located in relation to the thalamus?
Immediately below it
What are the functions of the hypothalamus?
- Control of emotional reactions
- Eating
- Drinking
Which other region of the brain does the hypothalamus have a direct connection with?
The pituitary gland
Why does the hypothalamus have a direct connection with the pituitary gland?
So that emtoinal reactions can trigger hormonal secretions
What are the constituent parts of the brain stem?
- Midbrain
- Pons
- Medulla
The ventral tegmental area is found within which area of the brain stem?
The midbrain
Which area within the brain stem is involved with addictions and rewards?
The ventral tegmental area
Which area of the brain stem is responsible for the control of arousal, waking and sleep?
The pons
The medulla is involved in which type of processes?
Subconscious processes
Which subconscious processes is the medulla involved with?
- Breathing
- Digestion
- Control of heart rate
- Blood vessel function
Which type of neurons can be found in the ventral tegmental area?
Dopaminergic neurons
Roughly what percentage of a person’s energy supply does the brain require?
About 20%
The blood provides energy to the brain in what form?
Glucose
What type of problem with a blood vessel can cause a stroke?
A rupture or blockage
What regulates the passage of substances to the brain?
The blood-brain barrier
What are the cell types which form the blood-brain barrier?
- Astrocytes
- Brain endothelial cells
- Pericytes
Within the blood-brain barrier, what is the function of the endothelial cells?
To form tight junctions in order to form a physical barrier between the brain and any unwanted substances
What are glial cells?
A type of cell which provides physical and chemical support to neurons and maintains their environment
What are astrocytes primarily responsible for?
Maintaining the overall environment of the brain
What are the different types of astrocytes called?
- Protoplasmic astrocytes
- Fibrous astrocytes
Where are protoplasmic astrocytes generally found?
In the grey matter of the brain
Where are fibrous astrocytes primarily found?
In white matter
What are the main functions of astrocytes?
- Providing physical support to neurons
- Regulating levels of substances such as potassium
- Helping to form the blood-brain barrier
What is the purpose of pericytes?
To help control the flow of blood in and out of the body’s tissues
The basal membrane surrounds which cells?
The endothelial cells
What essential components does the blood-brain barrier allow movement of between the blood and the brain?
- Fat-soluble molecules such as oxygen and carbon dioxide
- Glucose
- Amino acids
What are important implications of the blood-brain barrier?
Integrity can reduce with age, increasing the likelihood of conditions such as alzheimer’s
Which neurodegenerative diseases have been found to be linked to dysfunction of astrocytes?
- Huntington’s chorea
- Parkinson’s disease
- Amyotrophic lateral sclerosis (ALS, aka Lou Gherig’s disease)
Which feature of the blood-brain barrier is responsible for ensuring that bacteria and viruses cannot cross into the brain tissues?
The tight junctions between endothelial cells
What is the neurovascular unit?
The collection of cells of the brain which help regulate blood supply to the brain
What can astrocytes detect?
Activity in neurons
What can astrocytes alter?
The dilation of blood vessels according to the activity of the neurons in a particular region of the brain
What are the cells of the neurovascular unit?
- Neurons
- Astrocytes
- Endothelial cells
- Microglial cells
- Pericytes of the blood
Broadly speaking, what is the neurovascular unit composed of?
A collection of cells
What is the neurovascular unit pivotal in maintaining?
Brain homeostasis
Put simply, what are the functions CSF provides?
- Cushioning and buoyancy
- Physical protection
- Control of pressure in the brain
- Clearance of waste products
In which parts of the brain is CSF produced?
The choroid plexus
What is the choroid plexus?
The region of the ventricles which produces CSF by way of filtration of the blood
How can be CSF also be described?
As an ultra-filtrate of blood plasma
In which area of the ventricles is CSF produced?
The choroid plexus
What is the function of the choroid plexus?
To produce CSF via filtration of the blood
What types of electrolytes does CSF contain?
- Potassium ions
- Sodium ions
- Chloride ions
- Bicarbonate ions
What is the choroid plexus a network of?
Capillaries
Sampling CSF can be used to help diagnose which conditions?
- Parksion’s disease
- Multiple sclerosis
Raised levels of certain proteins are commonly found in the CSF of patients of which condition?
Alzheimer’s disease
What physical hallmark in the brain can be a sign of Alzheimer’s disease?
Enlarged ventricles
What was the German neurologist Korbinian Brodmann particularly influential in our understanding of?
Brain structures
In the 1930s, Henri Molaison had which parts of his brain removed in an attempt to treat his epilepsy?
- Hippocampus
- Amygdala
- Other regions of the medial prefrontal lobe
Due to the areas of his brain which were removed, Henri Molaison was left with severe memory impairments. What does this suggest about the functions of the amygdala and hippocampus?
That they are particularly important in the role of memory formation
Which regions of the brain are described as the medial temporal lobe memory system?
- Hippocampus
- Entorhinal cortex
- Perirhinal cortex
In patients with Parkinson’s disease, post-mortem studies of the brain have shown loss of neurons in which region of the brain?
Substantia nigra
What functions is the substantia nigra involved in?
- Movement
- Reward
- Addiction
What type of data does brain imaging provide?
- Quantitative
- Objective
What is spatial resolution?
A measure of the accuracy with which structures or activities can be localised within the brain and distinguished from one another
What is temporal resolution?
A measure of the accuracy of recording changes in activity over time
What is the default mode network (DMN)?
A collection of regions of the brain which are thought to be activated when someone is in ‘resting state’
Although we do not know definitively, which brain regions are thought to be involved in the DMN (default mode network)?
- Medial prefrontal cortex
- Parietal cortex
- Posterior cingulate cortex
When we need to choose which aspects of our environment require our focus, which network in the brain is activated?
The salience network
What is the salience network?
A network of brain regions which are activated when someone is engaged with complex, cognitively demanding tasks
What can be complications as a result of defects in the default mode network (DMN)?
- Various mental health conditions
- Neurodevelopmental conditions including depression, ADHD, ASD and schizophrenia
What unusual physical feature was found in Albert Einstein’s brain, post-mortem?
A greater than average number of connections between each side
What effect has stress been found to have on the hippocampus?
Decreasing its size
Evidence of a correlation between atrophy of the hippocampus and which condition has been noted?
Clinical depression
What is the term for a bundle of axons that connect one brain region to another?
Fibre tracts
Why is white matter white?
Because there is myelin present, coating the neuronal fibres
What is the name for the fatty substance which surrounds the axons of some neurons and acts to speed up transmission of electrical information?
Myelin sheath
Why is the myelin sheath important?
It speeds up transmission of electrical information
Which regions of the brain do association fibres connect?
Regions within the same hemisphere
Which regions of the brain doe commissural fibres connect?
Brain regions across the hemispheres
What structures are commissural tracts?
- Corpus callosum
- Fornix
- Anterior commissure
What is the largest commissural tract?
Corpus callosum
The frontal lobe is connected with association fibre tracts to which parts of the limbic system?
- Amygdala
- Hippocampus
What is meant by the term brain lateralisation?
The tendency of one side of the brain to be dominant for particular tasks
In the majority of people, what is the left side of the brain dominant for?
Naming objects
The production of speech is largely controlled by which side of the brain?
The left side
Diminished connectivity between hemispheres may be implicated in which conditions?
- ADHD
- Autism
- Schizophrenia
Diffusion weighted magnetic resonance imaging can be used for what purpose?
Mapping the projection of fibre tracts
The map of all the various connections of fibre tracts within the brain is called what?
Connectome
What is the name for the spaces in the brain which are filled with CSF?
Ventricles
Which area of the brain is responsible for regulating complex cognitive functions such as empathy, decision making and impulse control?
Anterior cingulate cortex
The parietal lobe is responsible for what?
- Awareness of body position
- Processing information about touch
What is the name for the part of the brain which is located in the inferior (caudal) region of the brain?
The brainstem
Involuntary processes such as heart rate and breathing are controlled by which region of the brain?
Brainstem
What is the proper name for the region of the brain which is sometimes referred to as the “relay centre”?
Thalamaus
Much of the information from the sensory organs that reaches the brain is processed in whcih area?
Thalamus
