The Structure and Function of the Nervous System Flashcards
1
Q
what is the CNS composed of ?
A
brain and spinal cord
2
Q
what is the PNS composed of ?
A
composed of nerves that connect the brain or spinal cord with muscles, glands and sense organs
3
Q
define ‘neurotransmitters’
A
neurotransmitters are the chemical transmitters released from the neurones in response to chemical signals
4
Q
define ‘processes’
A
the long extensions that connect neurones to each other
5
Q
define ‘cell body’
A
also called the some; contains nucleus and ribosomes(protein synthesis)
6
Q
define ‘dendrites’
A
branched outgrowths from the cell body/some that receive signals
7
Q
define ‘dendritic spines’
A
knob-like outgrowths that receive inputs
8
Q
define ‘axon’
A
the ‘nerve fibre’; a long process extending from the cell body/soma that carries signals to target cells
9
Q
what is the size of an axon ?
A
ranges form 1 um to 1 m
10
Q
define ‘initial segment’
A
the ‘trigger zone’ on the axon
11
Q
define ‘axon collateral’
A
axon branches which carry the signal ‘sideways’
12
Q
define ‘axon terminals’
A
the end of the axon which establishes synaptic contact with another neurone of an effector cell
13
Q
define ‘varicosities’
A
bulging areas along the axon at which neurotransmitters can be released from
14
Q
Neurones are wrapped in myelin. What is myelin ?
A
20-200 layers of modified plasma membrane
15
Q
what is Myelin made of in the CNS and in the PNS ?
A
CNS - oligodendrocytes
PNS - Schwann cells
16
Q
define ‘axonal transport’
A
to maintain the structure and function of the nerve fibre, organelles must more more than 1 m between the soma and the axon terminals via a process called ‘axonal transport’
17
Q
what is axonal transport dependent on ?
A
Motor proteins called Kinesins and Dyneins
18
Q
how do the Motor proteins in axonal transport work ? (2 points)
A
- at one end, the motor protein binds to the cellular cargo
- at the other end, the motor protein uses energy derived from ATP to ‘walk’ up or down the axon
19
Q
state 2 facts about ‘Kinesin transport’
A
- Kinesin transport occurs at the cell body and carries down the axon (anterograde)
- carries nutrients, molecules, mitochondria, neurotransmitter filled vesicles, and other organelles
20
Q
talk about ‘Dynein transport’ (2 points)
A
- retrograde (opposite direction to Kinesin transport)
- carry recycles membrane vesicles, growth factors, and other chemical signals that effect a neurones morphology, biochemistry and connectivity
21
Q
talk about a potential danger associated with ‘Dynein transport’
A
the route at which some harmful agents enter the CNS (eg - polio virus)
22
Q
state the three types of neurones
A
- afferent - sensory - convey info to CNS (enter via dorsal)
- efferent - motor - convey info from CNS (exit via ventral)
- interneurone - convey into within CNS (reflexes between afferent and efferent neurones)
23
Q
state 2 facts about afferent/sensory neurones
A
- transmit into to CNS from receptors at their peripheral endings
- cell body and peripheral process in the PNS; short central process and axon terminals in CNS
24
Q
state 2 facts about efferent/motor neurones
A
- transmit info out of CNS to effector cells
2. cell body, dendrites and small portion of axon in CNS; most of axon in PNS
25
state 4 facts about interneurones
1. integration and signal changers
2. create a reflex circuit
3. lie entirely within the CNS
4. constitute for > 99% of the total neurones in the human body
26
define 'nerves'
groups of afferent and efferent neurones together within a connective tissue sheath
27
define 'synapses'
the anatomical specialised junction between two neurones which neurotransmitters diffuse across
28
A) what proportion of the neurones in the CNS are composed of Glial cells ?
B) what proportion of the space in the CNS is composed of Glial cells ?
A) 90%
B) 50% (neurones branch more extensively than Glial cells so take up more space)
29
what is the main function of Glial cells ?
surround the Soma, axon and dendrites and provide them with physical and metabolic support
30
state 2 functions of Astrocytes (type of glial cell)
1. regulate extracellular fluid by removing potassium and neurotransmitters
2. form tight junctions with cells forming capillaries forming a blood-brain barrier (prevents toxins and other substances entering the brain)
31
what is the function of the microglia (type of glial cell) ?
specialised macrophage like cells
32
what is the function of ependymal cells (type of glial cell) ?
they line the fluid filled cavities within the CNS and regulate the production and the flow of cerebrospinal fluid
33
the PNS is divided into two divisions, what are they ?
1. efferent division
| 2. afferent divison
34
what are the 3 divisions of the afferent division of the PNS ?
1. somatic sensory
2. visceral sensory
3. special sensory
35
what are the two divisions of the efferent division of the PNS ?
1. somatic motor
| 2. autonomic motor (sympathetic, parasympathetic, enteric)
36
define 'pathway/tract'
a group of axons travelling together within the CNS is called a pathway/tract
37
define 'a commissure'
a commissure occurs when a group of axons link the left and right side of the brain together
38
define 'ganglia'
ganglia are the cell bodies of neurones with similar functions within the PNS
39
define 'nuclei'
nuclei are the cell bodies of neurones with similar functions within the CNS
40
are there nerves in the CNS ?
NO, there are no nerves within the CNS
41
define 'nerve'
a nerve is a group of axons travelling together to and from the same general location in the PNS
42
what is the largest component of the forebrain ?
the cerebrum - consists of the R+L hemispheres and is connected by a corpus collosum
43
what is the central part of the forebrain ?
the diencephalon
44
what is the cerebral cortex ?
a 2-4 mm thick membrane surrounding the cerebral hemispheres
45
what are the outer and inner layers of the cerebral cortex made of ?
outer - grey matter (gives brain its grey appearance)
inner - white matter (mainly myelinated fibre tracts)
46
what are the two cell types within the cerebrum ?
1. pyramidal cells - major output cells
| 2. non-pyramidal cells - major input cells
47
The cerebral cortex is the main integrating centre for the nervous system. State two expansionary facts to this statement
1. basic afferent information is processed into meaningful perceptual images
2. has control over the system that govern muscle movement, and can refine the movements
48
state the 3 parts of the Diencephalon (part of the forebrain)
1. Thalamus
2. Hypothalamus
3. Epithalamus
49
state 4 facts about the Thalamus
1. a collection of several large nuclei
2. role in general arousal
3. role in controlling movement and posture
4. focusing attention
50
state 2 facts about the Hypothalamus
1. constitutes only 1% of total brain mass
| 2. has homeostatic control over the internal environment
51
state a fact about the Epithalamus
controls biological rhythms (via the Pineal gland)
52
The Hypothalamus is the master control centre for neural and endocrine co-ordination. What does it control ? (2 points)
1. behaviours learning to the preservation of the individual (eg - eating and drinking)
2. behaviours leading to the preservation of the special (eg - reproduction)
53
where is the Hypothalamus situated ?
the Hypothalamus lies directly above, and is connected by a stake, to the pituitary gland (an important endocrine structure that the hypothalamus regulates)
54
what is the main function of the Cerebellum (2 points)
1. important role in the co-ordination of movements and controlling posture and balance
2. receives sensory info from the sensory system, and information from the parts of the brain concerned with movement
55
what is the Brainstem
The Brainstem is the 'reticular formation' --> the only part of the brain absolutely essential for life. It receives and integrates information from all areas of the CNS
56
what are the 3 main functions of the Brainstem ?
1. motor functions
2. CV control, RS control and swallowing
3. regulates sleep, wakefulness, attention and eye movement
57
what are Meninges ?
Meninges line the structures in the CNS; add additional support and protection
58
what are the 3 Meninges ?
1. dura mater
2. arachnoid mater
3. pia mater
59
state the 4 functions of the Meninges
1. cover and protect the CNS
2. protect blood vessels and enclose the venous sinuses
3. contain cerebrospinal fluid (CSF)
4. form patricians in the skull
60
starting at the scalp, and moving inwards, what are the 7 structures surrounding the brain
1. scalp
2. skull bone
3. dura mater
4. venous blood
5. arachnoid mater
6. subarachnoid space of brain
7. pia mater
61
what is cerebrospinal fluid (VSF) ? (2 points)
1. it protects and cushions the brain structures
| 2. it is made by the Choroid Plexus
62
what structure produces cerebrospinal fluid (CSF) ?
the Choroid Plexus
63
grey matter consist of what 4 things ?
1. interneuroens
2. cell bodies and dendrites of efferent neurones
3. axons of afferent neurones
4. glial cells
64
white matter consists of what ?
groups of myelinated axons
65
A) Afferent axons enter the CNS via what root ?
B) Efferent axons enter the CNS via what root ?
A) dorsal root
B) ventral root
66
A) how many pairs of cranial nerves are there ?
B) how many pairs of vertebral nerves are there ?
A) 12 pairs
B) 31 pairs
67
how many pairs of nerves are at each level of the vertebral column ?
1. cervical - 8 pairs
2. thoracic - 12 pairs
3. lumbar - 5 pairs
4. sarcal - 5 pairs
5. coccygeal - 1 pair
68
peripheral nerves can contain what ?
peripheral nerves can contain nerve fibres that are axons of afferent neurones, efferent neurones, or both
69
state 3 facts about the somatic nervous system
1. consist of a single neurone between the CNS and the muscle cell
2. innervate skeletal muscle
3. ONLY excitatory
70
state 3 facts about the autonomic nervous system
1. two neurone chain between the CNS and effector cell
2. innervate smooth and cardiac muscle, glands and GI neurones
3. excitatory OR inhibitory
71
the sympathetic autonomic nervous system secretes what proportions of epinephrine and norepinephrine ?
80% epinephrine
| 20% norepinephrine
72
in the autonomic division, where do sympathetic nerves leave the CNS ?
thoracic and lumbar regions (ganglia close to spinal cord)
73
in the autonomic division, where do parasympathetic nerves leave the CNS ?
brainstem and sarcal regions (ganglia close to the effector cells they innervate)
74
define 'dual innervation'
Dual innervation is when tissues/organs can be innervated by the sympathetic and parasympathetic nervous system. They act Reciprocally (as one inc^ the other dec^)
75
rest of digest = ?
parasympathetic
76
fight or flight = ?
sympathetic
