patho phys exam 2 - CNS slides 1-17 lecture Flashcards
overview of the brain
forebrain
- cerebrum
- diencephalon
- hypothalamus
cerebrum
brain stem
- midbrain
- pons
- medulla
CEREBRAL CORTEX
left & right cerebral hemisphere
longitudinal fissure
thin gray matter
- basal nuclei are in the gray matter because “nuclei” means cell bodies in the CNS and the gray matter is cell bodies
thick white matter
corpus callosum
- connects the left & right cerebral hemispheres of the brain
VOLUNTARY MOTOR ACTIVITY
primary motor cortex
Motor homunculus
this demonstrates the regions of the body that we have the most control voluntarily and also that those regions are often the smaller parts of our body
ie. we have more control over our lips and fingers than our back and turnk
back and trunk occupy a smaller portion of the brain and the lips and fingers occupy a larger portion of the brain
PROCESSING OF SENSORY ACTIVITY
somatosensory cortex
sensory homunculus
this demonstrates that the most sensitive-to-touch areas of our bodies are the smaller regions too I think because the eyes much more sensitive than the back
PROCESSING SENSORY ACTIVITY
on fingers
- the region has small receptive fields
- The receptive field on the skin surface is small and your brain will be able to detect more fine sensations
- each neuron has 3 nerve endings
on the bottom of the foot
- the region has large receptive fields
- The receptive field on the skin surface is large and your brain will not be able to detect more fine sensations and would detect them as 1 sensation rather than 2
- the one neuron has 6 nerve endings
review of the stimulus and the afferent fibers
- sense a weak stimulus in the sensory receptor: have a small magnitude of receptor potential: the small magnitude travels down the afferent fiber down to the afferent terminal where few NTs are released
- sense a strong stimulus in the sensory receptor: has a large magnitude of receptor potential: the large magnitude travels down the afferent fiber down to the afferent terminal where a lot of NTs are released
also the smaller the receptive field, the more sensitive the region of the body - finger has a smaller receptive field
the larger the receptive field, the less sensitive the region of the body - the back has a larger receptive field
LANGUAGE
hear words
- info sent to the Primary auditory cortex (perceives sound)
- info sent to
Wernicke’s area (plans content of spoken words)
- info sent to Broca’s area (programs sound pattern of speech)
- info sent to Primary motor cortex (commands facial and tongue muscles
to speak words)
see words
- info sent to Primary visual cortex (perceives sight)
- info sent to Wernicke’s area (plans content of spoken words)
- info sent to Broca’s area (programs sound pattern of speech)
- info sent to Primary motor cortex (commands facial and tongue muscles
to speak words)
BASAL NUCLEI/GANGLIA
FUNCTIONS
- Promotes purposeful muscle activity
- Inhibits useless movement
- Inhibits muscle tone
- Monitors & controls slow, sustained contractions
basal nuclei made of:
- Caudate nucleus
- Putamen
- Globus pallidus
- Claustrum
remember basal nuclei is part of the gray matter because it is nuclei which means that it is a cluster of cells and cluster of cells is in the gray matter
THALAMUS & HYPOTHALAMUS
FUNCTIONS OF THALAMUS
- Relay station & integrating center for
sensory input on its way to the cerebral cortex
- Screens out insignificant signals and routes important sensory impulses to the cerebral cortex
- Crude awareness of sensation
- Some degree of consciousness
FUNCTIONS OF HYPOTHALAMUS
- Regulates many homeostatic functions
- Link between nervous & endocrine systems
- Role in sleep-wake cycle
- Involved with the limbic system
LIMBIC SYSTEM
- Ring of forebrain structures surrounding the brain stem linked via neuronal pathways
- Has reward & punishment centers: NE, DA, and 5-HT are important neurotransmitters
FUNCTIONS
- Emotions
- Basic survival
- Motivation
- Learning
- Socio-sexual behavioral patterns
do endothelial cells have tight junctions
Endothelial cells do have a gap between them for soluble substances to pass through but the astrocytes initiate the formation of tight junctions and so there is no space between the cells and that is the BB barrier
what can pass the BBB
Lipid soluble can pass through but water soluble cannot pass through
Endothelial cells have tight junctions that are made by astrocytes
what is the filtrate for
Filtrate is from for the nourishment of the neuronal cells
ependymal cells have cilia that move to push the CSF through the CNS. brings nourishment rich CSF to various part of the brain
In the CSF - [Na+] is slightly high, [K+] is slight lower
does CSF have plasma protein
CSF will have no plasma proteins so the presence of plasma proteins will indicate infections. Either water infection or bacterial infection and we are worried about meningitis
Extract CSF to find infection. Where can you extract it? Do a spinal tap, usually it is clear. If it is cloudy it will indicate plasma proteins and this infections
Spinal tap can lead to severe headaches
The amount of CSF matters if you take out a few mL it will lead to headache
fetus & CSF
In the fetus, there is plenty of spinal fluid but not drained properly it will cause swelling and can lead to hydrocephalus. This can lead to seizures and mental retardation. In order to treat it, put inn a shunt to drain the CSF
what has the thalamus and hypothalamus
Diencephalon has the thalamus and hypothalamus
are certain parts of the brain independent or act alone from each other
no part of the brain is independent or acts alone. Movement might be controlled by cerebellum but other parts are involved in movement
Cerebral cortex: highly convoluted region. The whole point of the folding is to increase the surface area because it is trying to fit in more volume in a smaller space. If it were smooth, our head will be very big
what are the two parts of the brain called
what connects them
what is the structure that connects them made of and thus what color is it
what are the two matters of the brain
what is the white matter made of and thus what color is it
what is the gray matter made of and thus what color is it
Left and right hemisphere - two major hemispheres. Longitudinal fissure which is a deep cleft or valley. If you get a cross section you will see the the left and right which are connected by corpus callosum which are made of myelinated axons where info flows
Outside has gray matter and the inside has white mater. White matter composed of myelinated axons which are lipid rich and therefore look white in color. Gray matter consists of cell bodies and dendrites and some glial cells.
how is voluntary motor activity controlled
what kind of muscles are responsible for voluntary motor activity
Voluntary motor activity - how is it controlled? Voluntary: you control it, movement carried out by skeletal muscles. Motor: movement
Primary motor cortex: primary motor that controls movement
Central sulcus
what does homunculus mean
is movement of the body equally represented in the brain
does the trunk or fingers/eyes occupy a bigger portion of the brain and what does this mean for our control of it
how is occupying a greater portion of the brain connected to degree of motor control
why can we move our fingers so quickly and not oru mid section
communication is important so does the lips and jaw occupy a smaller or larger portion of the brain
Motor homunculus = little man
Movement of the body is not equally represented in the brain
The trunk occupies a really small portion of the brain so we do not have much motion for it but the fingers and eyes have occupy a larger portion of the brain so we have more control over it
Areas that are presented to a greater portion in the brain will have a higher degree of motor control in the brain
Movement of fingers: can move very quickly and occupy a greater portion of the brain. But we cannot move the middle section of the body because it is a smaller portion of the brain
Lips and jaw: communication is important and so will occupy more portions of the brain
is the brain plastic or rigid
what does use it or lose it mean
are lips, face, nose more or less sensitive to touch than the back what does that tell you about its regions in the brain
which side of the body does the left side control and which side does the right control
The brain is plastic and can undergo modifications over a period of time. Example: if monkeys were trained to press the button to get food, they would keep doing it. And so the index finger will occupy more function of the brain
Use it or lose it - the more you use a part of the body the more the space it will take u in the brain. You brain gets remodelled the more you do something
Sensory activity. In the parietal lobe. If you cut across the dark line. Certain regions of the body that occupy a large section of the brain and certain regions of the body that occupy a small section of the brain. Lips, face, nose etc will be sensitive to touch, pain and such. If you poke the eye it hurts more than the back. The eye is much more sensitive
Left part of the brain controls the right side of the body, right part of the brain controls the left side of the body
what is a receptive field
what does a small receptive field mean
what does a larger receptive field mean
Why portions of the body are much more sensitive than other parts.
Receptive field: area of the skin which might be responding to a stimulus. Area that is repsonsilbelf for a neuron.
Small receptive field, neuron is responsible for a small section of the body.
But a larger receptive field neuron is responsible for a large section of the body
Touch face, fingers supply stimulus to 2 receptive fields. Touch the back of the leg, both fingers will touch 1 neuron and the brain will perceive it as 1 finger because 1 neuron is responsible for the sensation.
Low receptive field: smaller . High receptive field: larger
language
in hearing words, what is the pathway that the info goes
what does the wernick’s area do
what does the broca’s area do
comprehension is responsbible in which area
ability to speak words is responsbible in which area
Language:
hear words, sent to the primary auditory cortex. See words: sent to occipital lobe.
Both are sent to wernicke’s area then Broca’s area: wernicke’s area helps to understand what’s happening
Broca’s area decides what you will you say and that is sent to the primary motor cortex to initiate action
Comprehension is responsible: wernicke’s areas.
Speaking ability is responsible: broca’s area. Present in the left hemisphere
Broca’s area is responsible for our ability to speak words. Wernicke’s area is responsible for our ability to understand those words.
what happens is baby has damage to left hemisphere, what if an adult?
what are the Broca’s area and the wernicke’s areas responsible for
why can babies learn lanaguages so easily
is it easier or harder for adults
Baby has Damage to the left hemisphere: this will go to the right hemisphere. If adolescent then it may be regained. But in adults, speaking ability will be permanently lost
Broca’s area: speaking ability. Wernicke’s area: comprehension (understanding what is going on)
Babies: when born, theory that they can only speak twi or only chinese. Not true but because they are exposed to those languages. Synaptic connections get strengthened and the ones not used will be strengthened. Easy to learn
Adults: really hard to learn
what is the basal nuclei and where is it
what is a ganglia and where is it
what regions are present deep in the white matter
what is the function of the basal nuclei
Basal nuclei/ganglia - means connection of neuronal cell bodies. In the CNS, neuronal cell bodies are nuclei. Outside of CNS, neuronal cell bodies are ganglia.
Regions present deep in the white matter are the basal nuclei. Functions are listed in slides. Purposeful muscle movement: pick up a pencil when you need it.
Inhibits useless movement: like tremors, doing something without purpose and will not build usefulness.
basal nuclei is a part of the gray mater since it is a collection of cells
people have a hard time with purposeful movement and they experience restless tremors and shaking when trying to pick up water - which part of the brain is responsible for this
Going to drink water: do not overshoot (miss by too much, go past the cup) or undershoot (miss by too little, go too before the cup) because the basal nuclei keeps track of where your hands are. Important because parkinsons’ disease the exact opposite happens - so people have a hard time with purposeful movement and they experience restless tremors and shaking when trying to pick up water. Primary defect is in the basal nuclei
Basal nuclei/ganglia is composed of:
A
White matter
B
Gray matter
B- Gray matter - correct because neuronal cells bodies are the nuclei and ganglia which are what the gray matter is composed of
where does all of the sensory info go to and after that where does it go to
what can the thalamus do to sensory info that is not important
what does the hypothalamus do
does the hypothalamus have a blood brain barrier
All of the sensory info goes to the thalamus which goes to the higher portion of the brain
Thalamus can screen out info overtime because it will realize that it is not important and will not carry the info to the upper portion of the brain
Distinguish something warm or hot is touching body but will not tell you where it is coming from
Hypothalamus sees what needs to be done and sends signal to an organ
- Sleep wake cycle is the circadian rhythm
- Hypothalamus has no blood brain barrier which allows the hypothalamus to send info from the body
LIMBIC SYSTEM
what is it responsible for
which part of it is responsible for fear
what happens if that part is removed
what kind of centers does it have
what is the punishment center
how do we treat depression
Responsible for emotion (anger, happy)
Fear is controlled by the amygdala. Generates fear response. If removed, they become fearless because they do not have amygdala. It tells you whether doing something will harm you or not
Has reward and punishment centers and have NTs like norepinephrine, dopamine etc. during certain activities these NTs are released and make you feel happy and that is reward center
Punishment center: burned by coffee so you won’t do it again
Study depression and anxiety - these come from the limbic system. Treat them by increasing [ ] of NTs so reward systems get reactivated
limbic system and drugs of abuse
which center does drugs of abuse stimulate
if someone is screaming at you and your limbic brain is activated, can you control it
can babies?
Drugs of abuse - stimulate the reward center because you will feel good about it and want to do it again
Smile - means the same thing around the world.
A higher brain can control it. If someone is screaming at you at work. Your limbic system is activated but you know that it is not good so you control your anger. The limbic system we can control them but babies cannot lol. We train ourselves, our higher brain regions will control it, and over time
what parts of the brain are affected in a stroke
if tremors then the basal nuclei is affected
SPINAL CORD NERVES
white matter is the outside and the gray matter is the inside
Consists of, & connects each side by dorsal & ventral root
SPINAL CORD GRAY & WHITE MATTER
WHITE MATTER
- Ascending nerve fibers/tracts (blue)
- Descending nerve fiber tracts (green)
GRAY MATTER
- Dorsal horn
- Lateral horn
- Ventral horn
FUNCTIONS
- Link b/w brain & body
- Integrates reflex activity w/o involving brain
reflex arc
1 - thermal pain receptor in finger
2 - afferent pathway
3 - integrating center (spinal cord)
4 - efferent pathway
by now, the person moves their hand
5 - effectors
6 - ascending pathway to brain
