Lecture 1 & 2 : Organisation Of The Nervous System + CNS Structure Flashcards
(53 cards)
1
Q
How many neurons roughly are there and does the number change?
A
- 86 Billion Neurons
- Not making anymore, can’t replace but need to repair
2
Q
What is the prefrontal cortex responsible for?
A
- High order functions: Forward Planning, decision making, problem solving
- Also impulse control, attention, personality expression
- Also grows the last -> needs myelination
3
Q
What are Ependymal cells?
A
- Type of glial cell that line the fluid filled spaces in brain and central canal of the spinal cord.
- Thin membrane that separates cerebrospinal fluid from neural tissue (barrier)
- Produce cerebrospinal fluid and regulates absorption - cushions brain and spinal cord and transports nutrients/ waste
4
Q
What are neuroglia?
A
- Cells that provide metabolic support or immune protection for neurones
- 10x as many neuroglia than neurons
5
Q
What are the types of neuroglia in the Central nervous system (Brain and Spinal Cord) and the peripheral nervous system?
A
- Ependymal cells
- Oligodendrocytes
- Astrocytes
- Microglia
6
Q
What are Oligodendrocytes and what are their functions?
A
- Produce myelin which are protective and insulating sheaths over nerve fibres (axons)
- Facilitating rapid electrical impulse transmission
7
Q
What are Astrocytes and what are their functions?
A
- Star shaped cells
- Structural support, blood brain barrier maintenance (regulate biochemical environment) so it protects, nutrient supply, neurotransmitter regulation (uptake excess from synaptic clefts)
8
Q
What are microglia and what are their function?
A
- Fight off infection (phagocytosis)
9
Q
What are some of the features of a neurone?
A
- Dendrites
- Nucleus
- Cell body (soma)
- Axon hillock
- Axon
- Node of Ranvier
- Myelin
- Terminal boutons (axon terminals)
10
Q
What are the function of dendrites?
A
- Tree branch like structure from cell body
- Receive electrical impulses from other neuron’s and the environment in the form of chemical messengers (neurotransmitters) and process them whether Action P will be generated
11
Q
What is an axon hillock and node of ranvier?
A
- Axon Hillock: Bump in cell body that takes all the signals/ info and decides if it will pass the message or not
- Node of ranvier: Gaps in the myelin sheath in the axon. Allows ions to diffuse in and out propagating electrical signalling. Action potential happens in these gaps
12
Q
What is the direction of flow of info in a neuron?
A
- Unidirectional
- Flows from dendrites/ cell body to axon terminal
13
Q
What are some features of a neuronal synapses?
A
- Presynaptic axon terminal and post synaptic dendrite
- Mitochondria
- Synapse and synaptic cleft
- Synaptic Vesicles and receptors
14
Q
What do the words anterior, posterior, superior, dorsal, ventral and inferior mean
A
- Anterior: In front of
- Posterior: Behind
- Superior: Higher/ above
- Dorsal: Relating to the back/ posterior of structure
- Ventral: In front and lower side (abdomen)
- Inferior: Lower/ below
15
Q
What are the roles and anatomical features of the following central nervous system structures: cortex, gyrus, sulcus, brainstem, and spinal cord?
A
- Cortex: brain’s outer layer, responsible for higher-order functions such as perception, thought, and decision-making.
- Gyrus: raised tissue on the cerebral cortex, increases SA for neural processing.
- Sulcus: groove on the cerebral cortex
- Brainstem: connects the brain to the spinal cord. It regulates heart rate, breathing, and consciousness.
- Spinal Cord: cylindrical structure transmitting neural signals between the brain and the rest of the body, and coordinating reflexes.
16
Q
What is the Cerebellum important for?
A
- Beneath Occipital lobe and Mini brain and contains more neurons that rest of brain
- Co-ordinating movement and balance, language processing and memory (cognitive)
- Cerebellum: beneath occipital lobes, responsible for coordinating voluntary movements, balance, and posture.
17
Q
What does grey matter and white matter consist of?
+ what is a longitudinal fissure
A
- Grey matter: Dendrites and Cell body of neurons
- White matter: Axons and myelin sheaths make it white
- Groove in the middle that separates 2 hemispheres of the brain
18
Q
What are the 4 lobes of the brain?
A
- Frontal
- Parietal
- Temporal
- Occipital
19
Q
What is the Frontal Lobe responsible for?
A
- Motor control (movement)
- forward planning/ decision making
- recognition of smell
- speech
20
Q
What is the parietal lobe responsible for?
A
- Identify objects
- Pain and touch sensations
- Understanding speech
21
Q
What is the occipital lobe responsible for?
A
- Vision
22
Q
What is the temporal lobe responsible for?
A
- Short term memory
- Hearing
- Smell recognition
23
Q
What are some features seen on the inside of the brain and what do they do?
A
- Corpus Callosum: Thick bundle of nerve fibres that connect the 2 hemispheres together
- Thalamus: Receives sensory info except smell and distributes to brain
- Hypothalamus: Releases hormones
- Pituitary Gland: Dumps hormones into blood stream
- Midbrain, Pons, Medulla oblongata (brain stem)
24
Q
What is the Cerebrospinal fluid?
A
- Flows from ventricles to subarachnoid space, reabsorbed into blood in dural sinuses through arachnoid villi.
- Fills ventricles (cavities) in brain and absorb shock
- A medium for nutrient and waste exchange
- Formed in choroid plexus (network of capillaries in the pia mater) and Ependymal cells
25
What are the divisions of the nervous system?
- Central nervous system: Brain and spinal cord
- Peripheral nervous system: Everything outside the CNS
26
What are the major structures of the nervous system
- Brain
- Spinal Cord
- Cranial Nerves
- Spinal Nerves
- Ganglia
- Enteric Plexuses
- Peripheral Nerves
- Sensory receptors
27
What are the names and functions of the sub divisions of peripheral nervous system?
- Autonomic Nervous System: involuntary control, regulates processes (homeostasis) (HR, BP, digestion, breathing rate)
- Somatic Nervous System: Voluntary (muscle movement and sensory info from skin)
28
What are the divisions of the autonomic nervous system?
- Parasympathetic: Rest and digest (cranio-sacral outflow)
- Sympathetic: Fight or Flight (thoraco-lumbar outflow)
29
What is the layer that wraps around the brain called and what are the 3 layers of tissue called?
- The meninges
- 3 layers called Dura mater, arachnoid mater and pia mater
30
What is the dura mater and what does it cover?
- Outermost layer - protecting from outside
- Consisting of periosteal layer and meningeal layer
- Tough outer layer
- Continuous with epineurium of the spinal nerves
31
What is the arachnoid layer?
- Second layer
- Thin membrane and wispy
32
What is the pia mater layer?
- Bound tightly to the surface and covering brain
- Forms the filum terminale which anchors spinal cord to coccyx (last bone of the bottom base of the spine)
- Form the denticulate ligaments that attach the spinal cord to durability
33
Why are the different spaces called in the brain?
- Epidural: external to the dura
- Subdural space : serous fluid
- Subarachnoid : between pia and arachnoid. Filled with CSF
34
What are the 3 major vessels that supply the brain ?
- Internal carotid arteries: supply anterior and middle parts
- Vertebral arteries: Supply posterior part. Branching from subclavian artery and merge to form basilar
- Basilar artery: supplies brain stem and cerebellum as contributes to posterior supply. Union of vertebral.
35
What is the Blood brain barrier and how is it formed?
- A highly selective permeable membrane.
- Separates circulating blood from brain
- Formed by capillary endothelial cells, which are connected by tight junctions
36
What is the function of the blood brain barrier?
- Allows passage of water, some gases, lipid soluble molecules by passive diffusion
- Selective transport of molecules (glucose/AA) for neural function)
- Prevent neurotoxins and drug entry by way of an active transport mechanism mediated by P-glycoproteins
37
What is one of the roles of Astrocytes foot processes in the blood brain barrier and why is useful?
- Astrocytes feet sécrète parachronisme that promote tight junction formation
- Tight junctions prevent solute movement between endothelial cells
38
What structures does the hindbrain contain?
- Cerebellum
- Pons
- Medulla oblongata
39
What structures does the midbrain contain?
- Tectum: superior colliculi (vision) and inferior colliculi (hearing)
- Tegmentum: Substantia Nigra, periaqueductal grey
40
What structures does the Forebrain contain?
- Telencephalon: cerebral cortex, limbic system etc
- Diencephalon: thalamus, hypothalamus, pituitary and pineal gland
41
What are the main 3 specialisations of the cerebral cortex?
- Sensory areas
- Motor areas
- Association areas: integrate info from sensory and motor areas, can direct voluntary behaviours
42
Where is the primary somatosensory cortex and what is its function?
- Post central gyrus of parietal lobe behind central sulcus. Behind primary motor cortex
- Detecting and processing sensory info from the body
43
Where is the primary motor cortex and what is its function?
- Located in the precentral gurus
- Made of pyrimidal cells whose axons make corticospinal tract
- Consious control of precise movements
44
Name some higher brain centres involved in motor control
- Somatosensory cortex
- Motor cortex (M1)
- Supplementary area (SMA)
- Pre motor area (PMA)
45
What does the Limbic system control and what are the main features in it?
- Limbic System: motivation, learning and memory
- Cingulate Gyrus: Co-ordinates senses to emotions and pain
- Hippocampus: Learning and memory
- Amygdala: emotional responses and linking emotions with memory
46
What is the role of the hypothalamus (below thalamus)
- Recieves sensory inputs
- Sends neural outputs to motor control nuclei & sympathetic/parasympathetic nervous systems
- Sends neural and hormonal outputs to pituitary
- Regulates body temp, thirst, urine output
47
What does the midbrain control?
- Visual and auditory systems
- Portions of midbrain called red nucleus and substantia nigra (dark pigments contain dopamine producing neurons) involved in control of body movement
- Degeneration of neurons in substantia nigra is associated with Parkinson’s disease
48
What are the 3 important parts of cerebellum and what do they do?
- Vestibulocerebellum - balance and control of eye movement
- Spinocerebellum - Enhances muscle tone and co-ordinates skilled voluntary movement
- Cerebrocerebelum - Planning and initiation of voluntary activity by providing input to cortical motor areas involved in procedural memories
49
What is the Pons in the hindbrain responsible for?
- Motor control and sensory analysis
- Acts as sensory/motor relay centre
- Support control respiration
- Maintain sleep wake cycle
50
What is the Medulla oblongata responsible for in the hindbrain?
- Contains relay stations and reflex centres
- Contains cardiovascular (regulates rate and force of heartbeat) and respiratory (basic breathing rhythm) rhythmicity centres
- Acts as a protective system that eliminates things through sneezing and coughing
51
Where is the reticular activating system and what does it control?
- Network of neurons in the brain stem (hindbrain)
- Arousal, sleep, pain and muscle tone (alertness and wakefulness)
- Ascending fibre sends signals upward
- Arouses and activates cerebral cortex
52
Describe the pathway when a hammer is hit on the tendon of the knee
- Stimulus: Hit
- Receptors: Muscle spindle stretches and fires
- Afferent path: action potential travels through sensory neuron
- Integrating centre: Sensory neuron synapses in spinal cord
- Efferent path 1: quadriceps muscle stretch, efferent path 2: hamstring muscle inhibited
53
What are the roles of the basal nuclei?
- Inhibition of muscle tone
- Co-ordination of slow, sustained movements
- Suppression of useless movements
