Nervous system Flashcards
What are cranial nerves?
Cranial nerves consist of 12 pairs of nerves that emerge from the spinal chord and follow defined paths to specific regions of the body.
What kinds of body parts can cranial nerves give information about?
Sensory: >Olfactory >Optic >Face, sinuses and teeth >Heart, lungs, bronchi, trachea, pharynx, larynx, GIT >Tongue, Tonsils >Ear
Motor: >Salivary glands >Pharynx muscles >Heart, lungs, bronchi, GIT >Trapezius muscles >Muscles of the tongue >Muscles of the face >Chewing muscles >External eyes muscles >Superior oblique muscle
Outline what divisions exist in the nervous system
Central nervous system:
>Brain
>Spinal chord
Peripheral nervous system:
>Sensory neurones
>Motor neurones
>Somatic nervous system
>Autonomic nervous system
>Sympathetic division
>Parasympathetic division
What division of the nervous system could a stroke impact?
A stroke would affect the CNS (brain).
Describe the central nervous system
> Consists of the brain and spinal chord
Describe the cerebrum
The cerebrum is separated into left and right parts (hemispheres) which control opposite sides of the body.
Each hemisphere is divided into 5 lobes:
- Frontal
- Parietal
- Temporal
- Occipital
- Insula
What are gyri?
The cerebrum is highly folded. the elevated bumps are gyri.
What are sulci?
The cerebrum is highly folded. the grooves or depressions are sulci.
What do sulci and gyri do?
Increase the surface area of the cerebrum.
What are the main functions of the frontal lobes?
> Conscious intellect
Judgement and ethics
Speech
Learned voluntary motor function
What are the parietal lobes responsible for?
> Recognition and correlation of sensation
What are the temporal lobes responsible for?
> Hearing
>Memory
What are the occipital lobes responsible for?
> Primary visual cortex - receives information from the eyes and interprets visual stimuli.
What is the hippocampus responsible for and where is it located?
The hippocampus is embedded deep into the temporal lobe.
> Memory - especially spatial memory
What is the corpus calossum responsible for and where is it located?
Located in the midline of the brain, the corpus callossum is a collection of commissural fibres connecting to corresponding grey areas of the left and right cerebral hemispheres.
What is the function of broca’s area and where is it located?
Located in the frontal lobe.
> Directs muscles of the tongue and mouth
Planning speech and other motor activities
What is the cerebellum and where is it located?
Located at the back of the brain.
> Coordination
Balance
Posture
Learned movements
What does the thalamus do and where is it located?
Located just above the brainstem.
> Sensory processing and interpreting
What does the hypothalamus do and where is it located?
Located below the thalamus.
> Controls homeostasis and the autonomic nervous system
Regulates thirst, feeding, pituitary hormones, temperature, blood pressure, biological rhythms
What is the limbic system and what does it do?
The limbic system is a set of structures in the brain that controls emotion, memories and arousal.
It contains regions that:
>Detect fear
>Control bodily functions
>Perceive sensory information
What is the reticular activating system and what does it do?
A network of neurones located in the brain stem that project to the hypothalamus to mediate behaviour, as well as to the thalamus and the cortex for activation of awake, desynchronized cortical EEG patterns.
What is in the brainstem?
The brainstem consists of the:
>Midbrain
>Pons
>Medulla oblongata
Can a stroke affect the brainstem?
Yes. A stroke in the brainstem can effect vital functions like breathing, vasomotor control and heart rate.
What does the midbrain do?
> Motor movement - especially in the eye
>Auditory and visual processing
What does the pons do?
> Acts as a conduction pathways between the higher and lower brain centres.
Respiratory control
Behavioural control and physiological responses
Visual and auditory reflexes
What does the medulla oblongata do?
> Control of HR, BP, RR
Vomiting
Swallowing
Coughing
Conduction pathway between the higher brain and the spinal chord
Contains many cranial and pre-sympathetic nerves
Compare the somatic and autonomic nervous systems
The somatic nervous system conducts impulses from the CNS to the skeletal muscles for VOLUNTARY contraction.
The autonomic nervous system conducts impulses from the CNS to smooth muscles, glands and cardiac muscles where movement is NOT UNDER CONSCIOUS CONTROL.
>Is divided into the sympathetic and parasympathetic divisions.
What is the peripheral nervous system?
Connects the body and the central nervous system.
Composed of all nervous tissue outside the central nervous system: >Cranial nerves >Spinal nerves >Ganglia >Sensory receptors
What is the sensory division of the peripheral nervous system?
The sensory/afferent nerves carry messages from the body to the central nervous system.
What do sensory recpetors do?
They respond to changes in the environment: >Light >Temperature >Pressure >Chemicals >Pain
And send sensory information to the CNS via the ganglia located outside the spinal chord.
What is the motor division of the peripheral nervous system?
The motor/efferent division takes messages from the central nervous system to the rest of the body.
It is divided into the somatic and autonomic nervous systems.
Describe the sympathetic nervous system
“Fight or flight”
>Increased alertness and metabolism
>What happens when we run is what we see when this system is activated
>Non-essential activities are decreased
Describe the parasympathetic nervous system
“Rest and digest”
>Slows down body activities except for digestion and urination.
Why is the brain considered to be “plastic”?
The only way we can learn or remember anything is if our brain physically changes!
The brain constantly changes as we have new thoughts or memories.
What is a synapse?
A junction between two nerve cells, consisting of a gap which impulses cross via diffusion of a neurotransmitter.
What are neurotransmitters?
Neurotransmitters are chemical messengers in the body.
They send information between neurones by crossing a synapse.
Describe the structure and function and a typical neurone
Neurons consist of: >Cell body >Axon >Node of Ranvier >Dendrites >Myelin sheath
What are the meninges?
The meninges refer to the membranous coverings of the brain and spinal cord.
Name the 3 layers of the meninges
From outside to inside:
>Dura mater
>Arachnoid layer
>Pia mater
What is the function of cerebrospinal fluid?
> Delivers nutrients to the structures of the nervous system
> Removes wastes from the brain and spinal chord
> Protects the brain and spinal chord from trauma
What is grey matter?
The darker tissue of the brain and spinal cord, consisting mainly of nerve cell bodies and branching dendrites.
When do we perform a lumbar puncture?
> To collect CSF in a suspected case of meningitis
> To inject medications into the CSF - particularly for anaesthesia or chemotherapy
> To detect the presence of malignant cells in the CSF
Where do we perform a lumbar puncture and why?
A lumbar puncture is performed between L3 AND L4 because the spinal chord ends at L1 AND L2 therefore, there is little danger in damaging the spinal chord or spinal roots below L3.
What is myelin and what does it do?
An insulating layer/sheath that forms around nerves.
> Protects and insulates nerves
Increases the speed of nerve impulses
What is blood-brain matter?
The blood brain barrier is a protective structure that limits potentially harmful substances reaching the brain.
Blood brain matter consists of:
>A continuous capillary endothelium
>A basement membrane
What substances can cross the blood-brain matter?
> Lipid soluble substances - eg. fats, fatty acids, O2, CO2, alcohol and nicotine
> Nutrients - eg. glucose, amino acids, some electrolytes
How does Parkinson’s disease affect the brain?
Parkinson’s affects the dopamine-producing brain cells in the substantia nigra. Without enough dopamine, it becomes harder to start and maintain movements, which leads to symptoms such as slowness of movement, rigidity and freezing.
How does dopamine relate to acetylcholine in the brain?
Acetylcholine release in the brain is known to modulate dopamine release.
