Extra (Final) Flashcards
Far more of the human brain is dedicated to [blank] than any other sense
Vision
What lies in front of photoreceptor cells at the back of the eye?
Neurons (transparent, do not hinder the very light sensitive photoreceptor cells) which are insensitive to light
How does the visual system solve the blind spot problem?
The optic disk (blind spot) is in a different spot in each eye
Left of fovea in left eye, right of fovea in right eye
Where are rods most abundant?
Where are cones most abundant?
Rods more abundant outside the fovea
Fovea has only cones
Difference of rods and cones with respect to light-absorbing pigments
All rods have same pigments (419 nm [white])
Cones have one of three pigments
S cone = 419 nm [blue, short]
M cone = 531 nm [green, medium]
L cone = 559 nm [red, long]
(Four pigments altogether form the basis of our vision)
(Frequencies shown are of max. absorption)
Constancy vs sensitivity of perceiving colour from blue, red, and green cones
Three cones are evenly distributed (perceive colour fairly constant across the visual field)
Numbers of red and green cones roughly equal, but there are fewer blue cones (not as sensitive to wavelengths in blue part of visual spectrum)
What are photoreceptors connected to?
Two layers of retinal neurons
First layer (amacrine, bipolar, horizontal cells)
Second layer (retinal ganglion cells)
Cortical columns
Strips of occipital lobe (0.5 mm)
What is the occipital lobe divided into?
6 visual regions (V1, V2, V3, V3A, V4, V5)
- V1 = primary visual cortex (striate cortex)
- Rest = extrastriate (secondary visual) cortex
Each extrastriate (secondary visual) cortex processes specific features of visual information
Each occipital region has different cytoarchitecture and unique inputs/outputs (different function)
Compression waves of changing air pressure (sound waves) move through what?
Compressible media, air, water, ground, etc. but not through vacuum of outer space
Sounds perceived as high pitched have ____?
More wave frequencies
(i.e., more waves per second)
In humans, the evolution of sound-processing systems for both language and music was accompanied by what?
Enhancement of specialized corticol regions (especially in temporal lobe)
Humans have marked expansion of auditory areas
Inner hair cells in the organ of corti synapse with what?
Neighbouring bipolar cells (axons that form the auditory nerve)
Free nerve endings for pain
(Nociception)
Slow
Free nerve endings for temp.
(Nociception)
Slow
Meissner’s corpuscle (touch)
(Hapsis)
Rapid
Pacinian corpuscle (flutter)
(Hapsis)
Rapid
Ruffini corpuscle (indentation)
(Hapsis)
Slow
Merkel receptor (steady skin indentation)
(Hapsis)
Slow
Hair receptors (flutter or steady skin indentation)
(Hapsis)
Slow
Muscle spindles (muscle stretch)
(Proprioception)
Rapid
Golgi tendon organs (tendon stretch)
(Proprioception)
Rapid
Join receptors (joint movement)
(Proprioception)
Rapid
Auditory pathway from cochlea to primary auditory cortex
Cochlea
Superior olives (hindbrain)
Inferior colliculus (tectum, midbrain)
Medial geniculate nucleas (thalamus, diencephalon)
Primary auditory cortex
In the four homunculus model of the somatosensory homunculus, what do each of the four areas correspond to?
3a - muscles
3b - skin (slow)
1 - skin (fast)
2 - joints, pressure
What does area 2 of the four homunculus (somatosensory) model contain?
Multimodal neurons responsive to force, orientation, and direction of movement
What would unilateral damage to the spinal cord at the shoulder do?
Loss of fine-touch and pressure sensation on the same side of the body below the shoulder
Loss of pain and temperature sensation on the opposite side of the body below the shoulder
For a corticospinal tract coming from the left hemisphere:
The anterior corticospinal tract would control what?
The lateral corticospinal tract would control what?
Trunk/muscles towards the midline on the left side
Limbs/muscles away from the midline on the right side
What transmitter activates skeletal muscles? It also inhibits heartbeat
Acetylcholine
What determines if a transmitter will be excitatory or inhibitory?
The ion channel and its associated receptor
What chemical (transmitter) accelerates heart rate in animals?
Norepinephrine
What releases hormones into the bloodstream to excite or inhibit targets?
The pituitary gland (under control of the thalamus)
What process corresponds neurotransmitters being released into the synaptic cleft?
Exocytosis
Peptide transmitters
Synthesized in the cell according to DNA instruction
Packaged in membranes in the Golgi body
Transported on microtubules to axon terminal
How does an action potential play an important role in step 3 (neurotransmitter transport and release into cleft) of neurotransmission?
- Action potential arriving at the axon terminal opens Ca2+ channels
- Ca2+ rushes in and forms a complex with synaptic vesicle
What are autoreceptors important for?
Negative feedback loop
Which glial cell is important to both uptake of neurotransmitters and the blood brain barrier?
Astrocyte
Gap junctions (electrical synapses) eliminate the 5 ms time delay in information, why are they not used more in the body?
Do not have plasticity (whereas chemical synapses do)
Can a neurotransmitter be excitatory at one location and inhibitory at another?
Yes
All motor neurons leaving the spinal cord use what neurotransmitter?
ACh
Small-molecule transmitters (amines)
Dopamine
Norepinephrine (noradrenaline)
Epinephrine (adrenaline)
Seratonin
Small-molecule transmitters (amino acids)
Glutamate
GABA
Glycine
Histamine
Small-molecule transmitters (purines)
Adenosine
ATP
Which two enzymes help make ACh?
Acetyl CoA and ChAT
acetyl coenzyme A
choline acetyltransferase
What medication is administered to help Parkinson’s disease?
L-dopa
Helps make more dopamine
What two transmitters are the ‘workhorses of the brain’ because so many synapses use them?
Glutamate and GABA
Families of peptide neurotransmitters
Opioids
Secretins
Insulins
Gastrins
Functions of neuropeptides
Hormones that respond to stress
Enable a mother to bond
Eating and drinking
Pleasure and pain
Contribute to learning
Predominant class of lipid transmitters
Endocannabinoids
Do cannabinoids dampen neural excitation or inhibition?
Both - since they inhibit the release of both GABA and glutamate
Examples of gaseous transmitters
CO
NO
H2S
At a skeletal muscle, cholinergic neurons are _____ ?
Excitatory (cause muscle contractions)
What is the single main receptor of the SNS system?
Nicotonic acetylcholine receptor
Least obstacles per route of drug administration
(Least obstacles)
Injecting into brain
Injected bloodstream
Inhaled into lungs
Injected into muscles
(Most obstacles)
Two types of ganglion cells
P (parvo, midget)
M (magno, parasol)
