Introduction to the Brain Flashcards
What is a neurone?
What are the basic functions of a neurone?
The most basic functional unit of the nervous system
they convey information via electrical signals
they receive information, integrate it and transmit it to other neurones
What is meant by an afferent neurone?
Sensory neurone
this carries information from receptors TOWARDS the CNS
What is meant by an efferent neurone?
Motor neurone
this carries information AWAY from the CNS, towards the peripheral effectors
What is meant by an interneurone?
This is a smaller neurone that links afferent neurones with efferent neurones within the CNS
They are only found within the CNS
What is the difference between a presynaptic and postsynaptic neurone?
Presynaptic:
- releases neurotransmitters as a result of an action potential travelling down the axon
- the neurone before the synapse
Postsynaptic:
- receives the neurotransmitter and the message
What are the roles of the dendrites?
They receive stimulation from other neurones, in order for the cell to become active
They conduct messages to the neurone cell body, allowing it to function
What is the role of the myelin sheath?
Myelin sheath allows electrical impulses to transmit quickly and efficiently along the nerve cells
What are the 3 different types of neurones?
- Bipolar
- Pseudo-unipolar
- Multipolar
What is meant by a bipolar neurone?
Where are they found?
It has only 2 processes extending from the cell body - an axon and a dendrite
Many are specialised sensory neurones for the transmission of sense
e.g. Proprioception, light, touch, hearing
What is a pseudo-unipolar neurone?
Where do they tend to be found?
It has only one extension from the cell body
The axon then splits into 2 branches - one travels to the CNS and one to the PNS
They tend to be sensory neurones and information is able to bypass the cell body
What is meant by a multipolar neurone?
Where do they tend to be found?
It has a single axon and multiple dendrites
This allows for a great deal of integration from other neurones
Tend to be motor neurones
What are the subdivisions of the nervous system?
It is divided into the central and peripheral nervous systems
Peripheral NS is divided into the somatic and autonomic nervous systems
Autonomic is divided into the sympathetic and parasympathetic nervous systems
What is the difference between the somatic and autonomic nervous systems?
Somatic:
- controls external actions of skin and muscles
- responsible for things we are conscious of feeling e.g. motor control
Autonomic:
- controls internal activities of organs and glands
- responsible for actions we are unaware are happening
What is the difference between the sympathetic and parasympathetic nervous systems?
Sympathetic:
- arousing - “fight or flight”
Parasympathetic:
- calming - “rest and digest”
Label the following directions when it comes to the brain
Ventral = towards the abdomen
Rostral = towards the face
Caudal = towards the tail
Dorsal = towards the back of the body
What are the two parts of the cerebrum (forebrain)?
- Telencephalon (outer brain or cerebral hemisphere)
- diencephalon (inner brain)
What components make up the brainstem?
- Midbrain
- Pons
- Medulla oblongata
How is the cerebrum divided?
It is divided into a right and left cerebral hemisphere
these are separated by the longitudinal fissure
What is the surface of the cerebrum marked by?
Elevated ridges (Gyri) and grooves (sulci)
What is meant by the corpus callosum?
It connects the right and left hemispheres and acts as a passageway for information to travel between them
Label the following Sagittal section of the brain
What is meant by a “ventricle” of the brain?
An expanded area in the brain that is filled with cerebrospinal fluid
they are located within the brain parenchyma
Why are the pons and cerebellum sometimes considered as the same structure?
They develop from the same embryonic tissue and share many functions
What is the purpose of the sulci and gyri?
The surface of the cerebral hemispheres are heavily folded to increase surface area
What is the difference between white and grey matter?
Grey matter contains nerve cell bodies
White matter contains nerve axons (and myelin sheaths)
Label the coronal section
What condition is shown in the scan?
Lissencephaly - “smooth brain”
leads to motor and sensory problems and mental retardation
lifespan is 5-10 years of age
What are the 3 main identifiable sulci in the brain?
Specific sulci are used to divide the cerebral hemispheres into lobes
- Central sulcus
- Lateral sulcus
- Parieto-occipital sulcus
What sulci are shown?
What is their function?
Lateral sulcus:
- Divides the frontal lobe and parietal lobe from the temporal lobe below
Central sulcus:
- divides the frontal and parietal lobes
Parieto-occipital lobe:
- divides the occipital and parietal lobes
Label the 4 lobes of each cerebral hemisphere (and the fissures)
What are the 2 main gyri to identify?
The sulci allow for specific gyri to be identified
Precentral gyrus:
- an area important for initiating motor control
Postcentral gyrus:
- the main area for receiving sensory information and processing it
Label the two main gyri
The precentral gyrus is within the frontal lobe
The postcentral gyrus is within the parietal lobe
What are the 2 components of the diencephalon?
Thalamus:
- an important relay station between the brainstem, spinal cord and cerebral cortex
Hypothalamus:
- controls the autonomic nervous system
- e.g. Heart rate, body temp, release of specific hormones
Label the inferior/ventral surface of the brain
What is significant about the inferior/ventral view of the brain?
It reveals a series of nerves known as cranial nerves
There are 12 pairs which generally supply structures within the head and neck
What is the first stage in development of the brain?
The neural tube begins to bend at the rostral end and develops three swellings which will develop into the brain
What are the names of the 3 swellings of the neural tube?
- Prosencephalon - forebrain (cerebrum)
- Mesencephalon - midbrain
- Rhombencephalon - hindbrain
The walls of the neural tube caudal to the rhombencephalon develop into the spinal cord
How do the three swellings of the neural tube then divide into 5?
Prosencephalon:
- divides into telencephalon (hemispheres)
- and diencephalon (inner brain)
Mesencephalon:
- does not undergo any change
Rhombencephalon:
- divides into metencephalon (pons and cerebellum)
- and myelencephalon (medulla)
Label the development of the mature brain from neural tube
What is meant by ventricles, connecting channels and vestigial?
Ventricles - expanded cavities within the brain
Connecting channels - link the ventricles
Vestigial - central canal of spinal cord
How many subdivisions of the CNS are there?
What are they?
6 or 7
- hemispheres
- diencephalon
- midbrain
- medulla
- cerebellum (and pons)
- pons
- spinal cord
It depends whether the cerebellum and pons are grouped together as one entity or not
