Physiology Midterm Flashcards
1
Q
What are the 3 main functions the nervous system uses to communicate and respond to environmental changes? And how do they work?
A
Sensory Input: allows us to read changes in the environment. This helps us survive and maintain a constant internal balance when faced with changes. In the traffic light example this occurs when we see a yellow light.
Integration: Is when the nervous system makes up a story about what is occurring. The first part of this is processing the information it is receiving from the sensory input. The second part is creating a plan of how to respond. It is understanding the meaning.
Motor Output: Is the physical act of the response. In the traffic example it is taking the foot off the accelerator and placing it on the break after seeing the yellow light.
2
Q
What does the central nervous system consist of?
A
The brain and spinal cord
3
Q
What happens in the spinal cord?
A
Where integration occurs
4
Q
What does the PNS consist of?
A
cranial nerves, spinal nerves, ganglia.
5
Q
What do spinal nerves do?
A
Take sensory input toward the CNS and send output to muscles/glands from the CNS
6
Q
What is ganglia?
A
is a junction point for elements of the CNS. It is an indirect junction between the PNS and the CNS
7
Q
What is a nerve?
A
is a collection of axons in the PNS
8
Q
What is motor input and sensory input?
A
Motor Output= information is carried away from the spinal cord
Sensory Input= information is moved toward the spinal cord because it is necessary for integration.
9
Q
What is the nervous system?
A
The master controlling and communicating system of the body
10
Q
What does the nervous system consist of?
A
Mostly cells which communicate with each other by electrical and chemical signals.
11
Q
What are the two ways the PNS is divided into?
What do they do?
A
Sensory/ afferent division & motor efferent version
Sensory/afferent division detects environmental changes, gathers information and sends it to the CNS. Example: blood pressure/ temperature. It has somatic and visceral fibres that go from receptors to the CNS
Motor/efferent: performs the actions (effectors)
Has motor nerve fibres from the CNS to effectors (muscles and glands)
12
Q
What do efferent and afferent mean?
A
Efferent: info sent away from CNS
Afferent: Information sent to the PNS
13
Q
Which muscles are voluntary/ involuntary?
A
Cardiac & Smooth= involuntary
Skeletal= Voluntary
14
Q
What is integration managed by?
A
The CNS
15
Q
How can the motor division be further divided?
A
Into the somatic nervous system (voluntary from CNS to skeletal muscles)
Autonomic Nervous System: involuntary (visceral motor) from CNS to cardiac muscle, smooth muscles and glands.
16
Q
What two ways can the Autonomic Division be further divided?
A
Sympathetic Division (fight or flight)
Parasympathetic Division (rest and digest)
17
Q
What do somatic and visceral mean?
A
Somatic: Information is going toward the muscles. It refers to the structure in the body (skin, bones, joints and skeletal muscles)
VIsceral: Internal Organs (stomach stretching out after you’ve eaten a meal)
18
Q
What are some examples of glands?
A
tear, sweat, salivary
19
Q
What is nervous tissue comprised of?
What are the two types of cells?
A
cells and minimal extracellular matrix.
a. neuroglia which are small supportive cells
b. neurons- excitable cells that transmit impulses.
20
Q
What are the 4 types of Neuroglia in the CNS?
A
Astroctyes
Microglia
Ependymal Cells
Oligodendrocytes
21
Q
What are astrocytes and from what system?
A
CNS system. Star shapes, most abundant and they help anchor neurons to capillaries. They help to control the external environment of the neuron because the neurons are easily excitable and must be tightly controlled. They have a role in nutrient exchange and in maintaining the blood-brain barrier. They control the environment by absorbing and recycling neurotransmitters.
22
Q
What are microglia?
A
CNS system. Protective, they remove cell debris, wastes and pathogens. They can transform into macrophages to destroy what is not needed.
23
Q
What are Ependymal Cells? What system?
A
CNS. Ciliated cells that line the cavities of the brain and spinal cord as a barrier between the CSF and fluid bathing cells of CNS. The spaces include canals (ventricals in the brain) and these cells produce and circulate fluid via cilia. It is also where blood filtration happens and the cells modify the fluid in these cavities and then circulate.
24
Q
What are Oligodendrocytes and which system?
A
CNS. They are cells that are “few branches” they provide the myelin sheaths to the CNS neurons.
25
What are myelin sheaths?
They are made of fats (plasma membrane) and these speed up/conduct action potential. An example is when you run the quick contractions requires myelin sheaths so the signal arrives quickly. Action potential from neurons to smooth muscle don't require this because it doesn't need to happen as fast.
26
How are myelin sheaths made?
Axons send out these branches that wrap about the axon and the layering becomes the Myelin Sheath
27
What are the 2 types of Neuroglia in the PNS?
Satellite cells: control the external environment. They surround the cell bodies in ganglia and influence the chemical environment of the neurons.
Schwann Cells: Form the myelin sheath around larger neurons. They are vital to peripheral cell regeneration
28
What do neurons do?
They are the functional units of the nervous system. They conduct electrical impulses from one part of the body to another.
29
What are the special features of neurons?
Extreme longevity: if nourished will last whole life.
Amitotic: Unable to divide (irreplaceable)
They have a high metabolic rate. They are high activity and require sugar and oxygen.
30
What do all neurons have?
they are large complex cells consisting of a cells body and one or more processes.
31
What is a cell body?
also called the perikaryon or soma. It contains a large spherical nucleus. It is the biosynthetic centre. It posses extensive RER, ribsosome clusters, golgi and organelles. It is the receptive centre
32
What does biosynthetic mean?
manufactures the requirements for the neurons.
33
What are the 3 parts of a neuron?
```
Axon-long process
Cell body (reception and biosynthesis
Dendrites
```
34
What are axon terminals known as?
The secretory region where neurotransmitters such as ACHl are secreted
35
What does the Axon do?
Sends signals to the terminal. It is known as an impulse or conduction area.
36
What is another name for the cell body?
Perikaryon/soma
37
What is a collection of cell bodies within the CNS known as?
| The PNS?
Nucleus
| Ganglian
38
What are the two processes that extend out of the cell body?
Dendrites and Axons
39
What are dendrites?
Short, tapering branches extensions, there are usually hundreds per cell body. They have a large area for reception of signals from other neurons. They send incoming messages a short distance toward the cells body called graded potentials.
40
What do axons arise from? length and how many per neuron?
Arise from tapered region called axon hillock. They can be greater than 1 meter. A long axon is called a nerve fibre.
There is usually 1 per neuron. They have branches to form terminal branches which end at the axon terminal
41
What do axons do?
they generate signals and conduct them to the axon terminals and then release a chemical neurotransmitter into extracellular space.
42
What does the axon have?
the same organelles as the cell body, but it has no ribosomes and golgi apparatus. The axons quickly degenerate if they are cut. They have an elaborate cytoskeleton in the axon to move material to and from the cell body. (anterograde and retrograde)
43
What do anterograde and retrograde mean?
anterograde: from the cell body to the axon terminal (mitos, cystoskeleton, Neurotransmitters)
retrograde: from the axon terminal to the cell body (organelles to be degraded/recycles)
44
What are a collection of axons called in the PNS and CNS
PNS: Nerves
CNS: Tract
45
Peripheral Nervous System?
Consists of cranial, spinal nerves
46
Central Nervous System?
Consists of the brain and spinal cord
47
Sensory input
Sending info regarding changes to the environment to the CNS
48
Motor Output
An example includes stimulating a muscle to contract
49
Integration
Processing info and deciding how to respond to it
50
Schwann
A cell found within the PNS and forms the myelin sheath
51
Astrocyte
A cell that helps control the external environment of neurons
52
Ganglion
A collection of cell bodies in the PNS
53
Cell body
A cellular structure that receives information
54
Axon
A long cellular extension that generates and conducts signals.
55
How are neurons classified?
by the number of processes that extend from the cell body
56
What are the 3 types of neurons?
multipolar (3 or more)
Bipolar (2)
Unipolar (single that is divided into central and peripheral processes. The process acts as an axon. Dendrites are found at the end of the peripheral processes and is a receptive ending; mostly in ganglia of PNS and function as sensory neurons.
57
What is the most abundant neuron?
Multipolar
58
How are neurons classified? & What are the three types?
Functionally and according to the direction the electrical signal travels relative to the CNS
Sensory/afferent
Motor/efferent
Interneurons
59
What are sensory/afferent neurons?
They travel toward the CNS- They are primary, secondary and tertiary. They are uni and bi polar. Ex: touch- takes information from the skin to the spinal cord (primary sensory)
Nearly all sensory neurons are unipolar and cells bodies located in the ganglie ( outside the CNS)
60
Which sensory neurons are multipolar and where are they located?
Inside the CNS (secondary and tertiary) They move from the spinal cord to the brain
61
What are motor/efferent neurons?
Away from the CNS to effector organs like muscles and glands. They are multipolar, and most cell bodies reside within in the CNS
62
What are interneurons?
They are between the sensory and motor neurons. They are involved with the integration of information. They are found almost entirely within the CNS. 99% of the neurons in the body are interneurons. They are multipolar
63
What do neurons require?
electrical (graded and action potentials and chemical (neurotransmitter signals.
64
What do neurons do?
send signals to other neurons or effectos by way of the axons.
receive signals from other neurons on the dendrites and cells bodies
65
What is potential energy?
energy associated with separated ions and opposite charge. If you were to allow the door to open for flow of ions, it is the energy that exists between them
66
What is voltage?
measures the potential energy between 2 points (millivolts)
67
What is current?
The flow of electric charge from 1 point to another. (the flow when the ion gate opens)
68
What do ions need to cross?
Plasma membrane
69
What are the 4 types of channels for ions to cross through?
| What are the 3 gated channels called?
Non-grated/leakage channels= which are always open
Gated channels= requiring a signal to open/close the gates
Chemically gated= neurotransmitters/ hormone signals that bind
Voltage Gated= a change in membrane is a potential signal. It is based in a change in voltage/potential energy within the membrane.
Mechanically Gated= physical deformation (indented skin when touching opens channels)
70
What is an ion?
channel species with a charge
71
What is resting membrane potential?
Resting membrane potential: The measurement of potential energy in voltage. The neuron is not receiving or sending signals and is at rest. Usually is -70
72
Where are sodium and potassium originally found?
Sodium is found outside of the membrane
| Potassium is found inside the membrane
73
Why is the inside of the membrane usually negatively charged?
There are more potassium leakage channels and since they follow the concentration gradient many potassium ions leave the cell. Since there are now fewer ions inside the membrane in comparison to outside we say the RMP is -70 and thus negatively charged in comparison to the outside.
74
What is the resting membrane potential?
The measured voltage when the cell is not receiving or sending signals.
75
What is voltage?
The electrical energy potential due to separation of oppositely charged particles.
76
What does polarized mean?
Is used to describe signals. It means there is a difference between one side to the other.
77
What creates resting membrane potential?
differential permeability to sodium and potassium ions as well as their concentrations both inside and outside the cell
78
What is the net result with the difference in permeability? What drives these ions moving through the plasma membrane?
There is a different amount of leakiness between sodium and potassium because of the difference in the numbers of leakage channels.
Using ATP the S&P pump always brings sodium out and potassium in. It recycles ions back to the original site.
The difference in permeability is because they follow the concentration gradient and there are more doorways for potassium to move through and sodium.
79
What are signals?
When neurons use changes in their membrane potential to communicate
80
What are the 2 signal types?
Graded potential:
Short distance signals. A neurotransmitter binds to a chemically gated channel. Some get voltage change. In order to generate graded potential, neurotransmitters bind to chemically gated channels to allow more sodium to enter the cell and move membrane potential.
Action potentials (long distance)
81
What are graded potentials known as?
| What do they mean? When do they occur?
short lived signals. known as hyper-polarizations or depolarizations.
hyper-polarization: number is getting further from zero. Occurs when sodium moves out of the cell
Depolarization: Number is getting closer to zero
occurs when potassium moves into the cell
82
What are some characteristics of graded potential?
- spread in multiple directions
-is short lived
-decreases in size and strength as it travels
-can start out as different sizes
-produced on the cell body/dendrites
-can be stimulatory or inhibitory
the function is to determine if the receiving neuron will produce an action potential
83
Where is the GP the strongest?
At the site where it is produced
84
What so graded and action potentials represent?
a change from the resting membrane potential
85
What can only axons generate and why?
action potentials because the plasma membrane posses voltage gated channels which open and close in response to graded potentials
86
Where does the transition from graded potentials to action potentials occur?
the axon hillock
87
What determines if an action potential is produced?
whether or not a graded potential is depolarized to minimum -55 or hyperpolaized below -70
88
What phases of generation of action potential are there?
| How are they created?
polarization and depolarization
They are created by the opening of voltage gated channels in sequence of first sodium channels and then potassium.
The action potential develops at the axon hillock and then moved down the axon toward the axon terminals.
89
When are voltage channels closed and leakage channels open?
During the resting state
90
When do depolarization and repolarization occur?
Depolarization- when sodium rushes in pushing the number closer to zero. An action potential is only created after -55
Repolarization is when the potassium voltage channel opens and potassium rushes out.
91
What is propogration?
The conduction of an action potential where it travels all the way to the next neuron or effector.
Once Action potential is generated at the Axon hillock sodium will spread down the axon to open sodium voltage gate channels at the next segment of membrane to set up a new Axon potential. It always travels all the way down.
92
What is the absolute refractory period?
When a neuron is producing an action potential and is unable to produce a second one. The earliest possible period (after depolarization) where a second action potential can be produced. However, this can only occur when there are strong stimulants
93
What is the relative refractory period?
when weak stimmulants can be produced in the refractory period. and is used for smooth muscle wjem we don't want to have continuous or fast movement
94
What does conduction velocity of the ap along the axon depend on?
1. myelin sheath
| 2. axon diameter
95
What are myelin sheaths
White lipid proteins created by schwann cells in PNS and oligodendrocytes in CNS
-insulate axons and prevent movement across the membranes
96
What are nodes of Ranvier?
What is salatory conduction?
How much does myelination speed up AP?
myelien sheath gaps that posses votlage gated channels.
Ap's only occur at nodes of ranviere in myelinated axons and skips several areas of membrane
Speeds up 30 times
97
In a strong signal when can a second impulse begin in the refractory period?
As soon as depolarization occurs
98
Conduction velocity depends on?
| What are slower speeds used for?
myelin sheath
axon diameter
digestion. Faster speed if used for skeletal muscles like running away
99
What produces continuous conduction?
non-myelinated sheaths
100
Which Group is biggest and fastest (skeletal)
Middle?
Smallest and slowest (digestive)
Group A
B
C
101
What is a synapse?
Where do they occur?
What are the two types?
The junction between two neurons or between a neuron and effector where a transfer of signal occurs. Most occur between axonal endings of one neuron and the dendrites or cell bodies of other neurons
Chemical & Electrical
102
What is a chemcial synapse?
What are the 3 parts?
function by binding and releasing neurotransmitters. They can change in membrane permeability by binding to receptors and leading to opening/closing of channels
- axon terminal- from presynaptic neuron
- receptor region- on post synaptic
- synaptic cleft- located between axonal terminal and receptor region
103
What are mechanisms of synaptic communication?
Initiation:
1. Action potential: arrives at axonal terminal
2. Ca+++ gates open in presynaptic axonal terminal and ca++ enters
3. Neurotransmitter release
4. Neurotransmitter diffuses across cleft and binds to postsynaptic receptors
5. Ion channels open in postsynaptic membranes
Termination:
i)degredation- by enzymes of postsynaptic membrane
II) reuptake by presynaptic terminal
III)diffusion away from synaptic site
104
What happens as action potential moves down the terminal?
The potential moves down the axon and begins to move calcium into the axon terminal. The calcium enters the vesicles of the neurotransmitter and begins to migrate to the end of the terminal to release the neurotransmitter. It then begins to move across the synaptic cleft to teh cell body where it binds to receptors on the post synaptic cleft
105
What are pre synaptic and post synaptic clefts?
pre: sends the signal
post: receives the signal
106
What happens in the post synaptic cleft?
The neurotransmitter binding opens the chemically gates channel. This allows the ions to flow in or out and produces the gradient potential. Graded potential spreads toward the axon hillock which determines if the action potential will be sent if it is big enough
107
What three ways can the body end the stimulation?
pre-synaptic can reuptake the neurotransmitter. An example would be serotonin. The carrier channels move it back into the pre-synaptic neurons.
2. breaking down NT enzymes
3. nitrate oxide binds to receptor and diffuses away from the synapses,
108
What is a synapses?
| Synaptic cleft?
The connection between neurons or a neuron and an effector
| It is a gap between the axon terminal and the cell body
109
What part are axon terminals in?
the pre-synaptic neuron because they are sending the signal
110
What are EPSP's and IPSP's?
EPSP's are excitatory post synaptic and GP+ because it is exciting a neuron toward threshold
IPSP's are GP negtives because they are moving away from the threshold. It is known as the inhibitory post synaptic.
111
What are postsynaptic potentials?
What do they respond to?
What do they mediate?
graded potentials that are created when neurotransmitters bind to receptors on the receptive region of the neuron
They respond to checmials (ie chemically gated channels)
Channels mediate local changes in membrane potential: graded as per amount of neurotransmitters
112
What are the two types of post synaptic potentials?
Excitatory postsynaptic potentials (EPSP's)
| Inhibitory postsynaptic potentials (IPSPs)
113
What is the size of a graded potential determined by?
neurotransmitters
114
What do channels depend on to open?
which neurostransmiter is released
115
What is summation by postsynaptic neuron?
| What are the two types?
A single EPSP cannot generate and AP
EPSP's must add up to generate an AP
i)temporal
ii)spatial
Bothe EPSPs and IPSPs are incoming and whichever is greatest will dominate.
The axon hillock is the neural integrator
The most effective synapses are closes to the axon hillock
116
What does communication between two neurons or a neuron and an effector require?
electrical events (graded and action potentials) as well as a chemical event (binding of neurotransmitters)
117
What are neurotransmitters important for?
The generation of graded potentials which creates an electrical current
118
What is ACHl?
neurotransmitter released at neuromuscular junctions. After binding and producing effects ACh is released from the receptor and degraded by an ensyme located on the post synaptic membrane. It is secreted by all neurons that stimulate skeletal muscles and by some neurons of autonomic NS; also released from neurons within the CNS
It is found throughout the nervous system and brain
119
What are biogenic Amines?
includes catecholamines and indolamines
some of which are produced from tyrosine
They are found throughout the brain and are involved with emotions and controlling the biological clock. NE is involved with neurons of the autonomic nervous sysem
120
What is In the blood stream and synapse?
hormones and neurotransmitters
121
What are amino acids?
more difficuly to demonstrate a specific role
| include GABA, glutamate and others. So far the role is shown just in the CNS
122
What is a peptide?
| examples?
A small amino acid
substance p: involved with transmitting sensation of pain to brain
endorphins/enkephalins: involved with reduction of pain sensation during stress; these are natural opiates
123
What are purines?
ATP: a major excitatory NT in the CNS and PNS
Adensosine: potent inhibitor in the brain; caffeine blocks receptors for adenosine
124
What are dissolved gases?
NO (nitric oxide): Short lives, toxic gas, not stored in vesicles. Manufactured on demand and diffuses through membranes and binds to intracellular receptors. They have possible roles in learning and memory and relaxation of smooth muscles in intestines
CO: Carbon monoxide mode of action is similar to NO but the role is unclear.
125
What are endocannabinoids?
Naturally produced chemicals that bind to the same receptors as THC. They are involves with memory, appetite control and pain modulation
126
What do excitartory neurotransmiters do and what is an example?
depolarize
| glutamate
127
What do inhibitory neurotransmiters do and what is an example?
Inhibit (hyperpolarize)
GABA
Glycine
128
What are examples that do both?
ACH
| NE
129
What i an example of Excitatory neurotransmitter?
Inhibitory?
Both?
Glutamate
GABA & Glycine
Ach & Ne
130
How can ACh be excitatory when binding to receptors on skeletal muscle and be inhibitory when binding to receptors on cardiac muscle?
This is due to different receptor channels that they are lined with. It depends on the type of channels and receptors.
131
What are the two mechanisms of action that exist when neurotransmitters bind to the their receptors?
What is direct?
What is indirect?
Direct and indirect
Direct involves the binding of a neurotransmitter that leads to opening of ion channels; rapid action (example is Ach and amino acids)
The binding of Neurotransmitters leads to production of 2nd messengers and are longer lasting (example; biogenic amines and peptides)
132
What are neurotransmitter receptors?
- channel linked for direct action
| - G-protein-linked for indirect actions
133
How do the channel linked receptors open?
The binding of ligand
134
What is a direct mechanism?
If a receptor is on the same protein as the channel this is a channel linked receptor. The binding of a neurotransmitter leads to the opening of a channel
135
What is a ligand?
A ligand is anything that binds to a receptor. It could be a hormone, or neurotransmitter.
136
How does NT effect direct channel linked receptors?
The NT binding changes the shape of the channel and leads to an opening of channel and ions to pass through, this changes the membrane potential of a target cell. The effects are rapid and brief
137
Explain about Indirect G protein linked receptors
The effects of the NT binding are slower and prolonged. It leads to an activation of G-proteins and then to the production of second messengers.
The second messengers either control the opening/closing of ion channels or lead to activation of enzyme systems
138
The process of indirect linked receptors?
1. a ligand is the first messenger which binds and activates the receptor
2. The receptor activates the G-protein which uses energy similar to ATP. (GTP) It ultimately leads to the opening of a channel
3. The G-protein leads to an enzyme (chemical in cell) It is involved in the production of the 2nd messenger
4. The enzyme produces the 2nd messenger. The response is slow but prolonged.
139
What are neuron pools?
Groups of neurons within the CNS that work in groups
They are important for the integration of information
Most consist of throusands of neurons, some are excitatory and others inhibitiory
140
How can incoming information travelling along neurons be processed?
In serial of parallel pathways
141
What is serial and parallel processing?
What the connections creat?
Serial: Refers to a chain of neurons connected in a straight through matter to a specific destination (Ex: a reflex arc)
Paraellel processing: Has information travelling in different pathways that run parallel to each other and will process information simultaneously. Information is integrated in different regions of the CNS
It allows you to put parts together to understand a bigger picture
Converging and diverging circuits
142
What is the simple reflex arc?
Contains information about sensory input. It involves integration and motor output.
143
What are divergent circuits?
The ways neurons are connected. The information is travelling paralell
144
What is a reverberating circuit?
It is an echo signal and controls rhythmic activity
145
What are converging circuits?
They illicit membranes and this stimuli elicits memory. Multiple neurons converge to one area.
146
What are the different subdivisions of the brain?
1. cerebral hemispheres (largest. Left/right)
2. diencephanlon (thalamus, hypothalamus, epithalamus)
3. Brian stem (midbrain, pons, medulla oblongata)
4. Cereblleum (in the back. "Little brain"
147
What are ventricles?
Any space in the brain. An example is between the brain stem and the cerebellum. The ventricles have fluid inside called the cerebralspinal fluid. It is important and the fluid circulates in and out of the brain
-are continuous with one another and with central cavity of spinal cord
-filled with CSF and lined by ependymal cells
4 ventricles
148
What are the 4 ventricles within the brain?
i) paired lateral ventricles (C-shaped)- located within cerebral hemispheres.
II) Each lateral ventricle communciates with narrow 3rd ventricle in diencephalon via the interventricular foarmen (foramen of monro)
III)3rd ventricle continuous with 4th ventricle (dorsal to pons) via cerbral aqueduct (runs through the midbrain)
IV) 4th ventricle continuous with central canal of spinal cord
V)3 apertures in 4th ventricle connect ventricles to subarachnoid space (surrounds the brain)
149
What are fissures? and sulcus?
What lies between the brain tissue. FIssures are deeper than sulcus. The sulcuses are folded to increase surface areas.
150
What are the folded ridges of brian tissue called?
Gyrus
151
What are the cerebral. hemispheres?
The cerebral hemispheres are the superior parts of the brain. (83% of brain mass)
- surfaces consist of gyri(ridges) and sulci (grooves)
- the hemisphere are divided into -lobes, parietal, occipital, temporal and insular.
152
Ehat are 4 important grooves?
i) longitduinal fissues
II) lateral sulcus
III)central sulcus
IV) parieto-occipital sulcus.
153
What are the three regions of each cerebral hemisphere?
```
cortex (superficial gray matter)
White matter (internal)
Basal nuclei (gray matter located deep within white matter)
```
154
What does insular mean?
deep to other lobes and insulates
155
Where are the central, lateral and parietal sulcus located?
central: between the frontal and parietal lobes. It is close to the coronal suture
Lateral: between the temporal lobe and both of the frontal/parietal lobes
Parietal: between the parietal and occipital lobes
156
What is the cerebral cortex?
allows us to percieve, communicate, remember and understand, appreciate, and initiate voluntary movements (consious behaviour)
It consists of grey matter
Contains billions of neurons arranged in 6 layers. 2-4mm thick but convolutions triple surface area
157
What are 4 generalizations of the cerebral cortex?
1. 3 functional ares, motor, sensory, and association areas
2. Each hemisphere handles sensory and motor functions of the opposite side of the body
3. Largely symmetrical, but not 100% equal in function (lateralization)
4. no functional area of cortex acts alone; all conscious behviour involves entire cortex in some way
158
What are motor areas?
Areas of the cerebral cortex that control voluntary movement. They include regions in the posterior part of the frontal lobes: primary motor cortex, pre motor cortex, Broca's area and frontal eye field.
1. primary motor cortex
2. premotor cortex
3. broca's area
4. Frontal eye field
159
What is the primary motor cortex?
precentral gyrus of the frontal lobe of each hemisphere; the pyramid-shaped cells allow control of skeletal msucles; their axons project to spinal cord as pyramidal/corticospinal tracts.
The entire body represented spatially in primary motor cortex of each hemisphere (somatopy)
Face, tongue, and hands require most precise action/control and require more neurons devoted to this area.
Motor innervation is contralateral
160
What is the Homunculeaus?
A map os the body
1. samatopey
2. body parts in image do not represent proportions but rather how many neurons there are in that area due to dexterity requirments
161
What is the premotor cortex?
anterior to the precentral gyrus
involved with planning movements
learned motor skills that are repetitive/patterned (typing) are stored here.
It coordinated movements of several muscle groups
162
What is the broca's area?
motor speech area: controls muscles of the larynx, pharynx and mouth to create speech.
for most people it is located in the left hemisphere.
163
What is the frontal eye field?
Controls voluntary movements of the eyes.
