Study Guide Flashcards
(204 cards)
1
Q
- Describe the organization of the nervous system
A
CNS -> PNS -> Motor (Efferent) Divison
-> Autonomic or somatic nervous system -> ANS either goes to Sensory (Afferent) Division which will send the signal back to PNS then CNS or the ANS will go to either the sympathetic division or the para sympathetic division
2
Q
Why are neurons amitotic?
A
Because they don’t contain centrioles
3
Q
Do primary brain tumors originate from neurons in the brain or the supporting cells (neuroglial cells)?
A
neuroglial cells can multiply unlike neurons, brain tumors are basically uncontrollable growth
4
Q
How many axons can each neuron have?
A
one
5
Q
Which part of a neuron is referred to as the:
a. biosynthetic center and why?
b. receptive center and why?
c. conducting region and why?
d. secretory region and why?
A
a. Cell Body- Neurotransmitters
are synthesized in the cell
body hence referred to as the
“BIOSYNTHETIC region” a
neuron
b. Dendrites- Tapering processes that act as the “RECEPTIVE regions” of a
neuron
c. Axon-
the cell body – Generates and transmits action potentials AWAY from the cell body hence, known as the “CONDUCTING region” of a neuron
d. Axon Terminals- Store and release
neurotransmitter hence the axon
terminals are referred to as the
“secretory region” of a neuron
6
Q
Nissl body
A
well-developed rough
ER in cell body of neuron
AKA Chromatophilic
7
Q
nuclei
A
clusters of neuron cell bodies in the
CNS
7
Q
ganglia
A
cluster of nerve cells in PNS
8
Q
tract
A
bundle of axons in the CNS
9
Q
nerve
A
a bundle of axons in the PNS
10
Q
neurilemma
A
cytoplasm and the nucleus of the Schwann cell squeezed outside the myelin sheath, only in PNS because Schwann cells are only in PNS
11
Q
nodes of Ranvier
A
The spaces between adjacent myelin sheaths
12
Q
Describe the structural organization of a tract or nerve.
A
Axon -> Myelin Sheath -> Endoneurium membrane (delicate connective tissue)
*Bundle of these covered in perineurium membrane (coarse
connective tissue) is a fascicle
*Bundle of fascicles creates a tract or nerve covered in epineurium membrane (tough
connective tissue)
13
Q
What is a fascicle?
A
bundle of endoneurium-covered axons
each fascicle is covered by the coarse
connective tissue membrane called the
perineurium
14
Q
Name and give the location of each of the 6 types of supporting cells
A
In CNS:
Astrocytes
Microglia
Ependymal cells
Oligodendrocytes
In PNS:
Schwann cells
Satellite cells
15
Q
Astrocytes
A
Most abundant
Numerous extensions that wrap around neurons
Involved in forming the BLOOD-BRAIN BARRIER, a selective barrier that regulate the chemicals environment of the brain
Regulate brain function
16
Q
Microglia
A
Since the specific immune system does not have access to the CNS; the microglia are phagocytes to engulf/destroy pathogens and cell debris
Worse than microphages
17
Q
Ependymal cells
A
Ciliated columnar cells that line the ventricles – cavities in the brain that contain cerebrospinal fluid (CSF)
Currents created by beating of cilia circulate the CSF
18
Q
Oligodendrocytes
A
Their extensions myelinate axons of neurons in the CNS
One cell can myelinated multiple axons
Has myelin sheath but no NEURILEMMA
19
Q
Schwann cells
A
Myelinate axons of neurons in the PNS
One cell only wraps around segment of axon
Has myelin sheath (the concentric rings that wrap around axon) and NEURILEMMA (cytoplasm and the nucleus of the Schwann cell which is squeeze outside of myelin sheath)
20
Q
Satellite cells
A
Surround cell bodies of neurons to control their chemical environment
21
Q
Which type of supporting cells are involved in the formation of the Blood-Brain-Barrier (BBB)?
A
Astrocytes
22
Q
What is the function of the Blood-Brain-Barrier (BBB)?
A
a selective barrier that regulate the chemicals environment of the brain, stops harmful chemicals from coming into brain
23
Q
Which type of supporting cells in the PNS is analogous to the oligodendrocytes in the CNS?
A
Schwann Cells-
Both Myelinate axons in their respective nervous system
One cell only wraps around segment of axon while one oligodendrocyte cell can wrap around multiple axons
Schwann Cells have Neurilemma unlike oligodendrocytes
24
Explain why myelinated axons in the CNS do not usually regenerate when severed. Explain why myelinated axons in the PNS can regenerate when severed
When the axon is severed in the PNS, cells of the immune system clean up the damaged area of cell debris, a process known as debridement, which sets the stage for regeneration, macrophages are big helpers in this
The neurilemma of the Schwann cell forms a REGENERATION TUBE that guides regeneration of the severed axon
CNS doesn't have a neurilemma to form a REGENERATION TUBE nor do they have the cells to clean the area up
25
Discuss two factors that are responsible for establishing the resting membrane potential
Which channels are open across the cell membrane and the concentration of Sodium outside the cell to potassium inside the cell
26
Describe the three phases of an action potential
a. depolarization phase of an action potential is causes by entry of sodium ions (Na+) into axon referred to as sodium influx makes membrane potential less and less negative, has to reach -55 to shoot up to +30
b. repolarization phase of an action potential is caused by two events:
(i) sodium channels close (Na+ influx halts)
(ii) potassium channels open (K+ efflux begins) and potassium ions
(K+) rush out of the axon referred to as potassium efflux; this results in
reversal of themembrane potential toward a negative membrane potential
c. hyperpolarization phase is caused by more K+ efflux occurs past the RMP driving the membrane potential below the RMP
(RMP is restored by the Na+/K+ pump which pumps 3 Na+ out and 2 K+ in
27
How is the generation of an action potential affected in the presence of a Na+ channel blocker?
If the Na+ is blocked and the mV cannot reach -55 the acton potential will not happen
28
absolute refractory period of an action potential
coincides with the depolarization phase of the action potential when sodium channels are opened and therefore another action potential cannot be generated because all the Na+ channels are already opened, and depolarization is already occurring
29
relative refractory period of an action potential
coincides with the repolarization phase of the action potential when the sodium channels are closed ( potassium channels are open) thus, an exceptionally strong stimulus can cause sodium channels to open to allow for sodium ion influx leading to depolarization and the generation of another action potential
30
How do you tell the difference between a strong stimulus (such as an intense pain) and a weak stimulus (such as a mild pain) when both caused action potentials to be generated?
Frequency of impulse because the action potential will always look the same but the frequency controls the strength
31
Name and describe the 3 structural classes of neurons; which structural class is most abundant?
Multipolar neuron- at least 3 processes – one axon and at least 2 dendrites; most abundant neuron in the human body
Bipolar neuron- 2 processes – one axon and one dendrite
Pseudounipolar neuron- one short process extending from the cell body that bifurcates into a central process and a peripheral process
32
Name and describe the 3 functional classes of neurons; which functional class is most abundant?
Sensory or Afferent neuron- transmits impulses from sensory receptors TOWARD the CNS
Association neurons or interneurons- located in the CNS between the sensory neurons and the motor neurons
Most of the neurons (99%) in the body are association neurons
Motor or Efferent neuron- transmits impulses AWAY from the CNS to effector organs = glands, organs
33
Name and describe the 3 types of nerve fibers
Group A fibers- have the largest diameter and heavily myelinated: transmit impulse at the rate of 150 m/s ( 335 miles per hour). Ex. Motor neurons that innervate skeletal muscles
Group B fibers- intermediate diameter and lightly myelinated (with wider gaps of nodes of ranvier); transmit impulses at a rate of 15 m/s (33 miles per hour)
Group C fibers- smallest diameters and unmyelinated; transmit impulses at a rate of 1 m/s (2.2 miles per hour)
Ex. Postganglionic autonomic fibers that innervate smooth muscle’ pain fibers
main pain fibers
34
Nerve fibers slowest-fastest and why
A -> B -> C
This is because the myelin sheath makes conduction way faster, the potential can jump from cell to cell
35
Discuss two reasons why the conduction velocity is faster in a larger heavily myelinated axon than in a smaller unmyelinated axon
Diameter of the axon – larger axons transmit impulses at a faster rate than smaller axons because the larger axon have larger diameter and therefore presents with less resistance impulse transmission
Degree of myelination – myelinated axons transmit impulses at a faster rate than unmyelinated axons.
Myelinated axons use SALTATORY conduction where action potentials are generated only at the nodes of Ranvier hence, the impulse “jumps from node to node down the axon
Unmyelinated axons use CONTINUOUS conduction where action potentials developed stepwise across the entire axolemma
36
SALTATORY conduction
action potentials are generated only at the nodes of Ranvier hence, the impulse “jumps from node to node down the axon
37
CONTINUOUS conduction
action potentials developed stepwise across the entire axolemma
38
Explain what happens to the conduction velocity when myelinated axons become demyelinated
Conduction velocity decrease severely
39
Name the 4 structures protecting the brain
Cranium, Meninges- 3 connective membranes surround the brain- Dura mater and Arachnoid mater and Pia mater, Cerebrospinal fluid (CSF), Blood-Brain barrier
40
What is the significance of the Blood Brain Barrier? Name the supporting cells involved in the formation of the Blood Brain barrier
Prevents harmful chemicals from coming into the brain from bloodstream
Astrocytes help form this barrier
41
Name and describe the 3 types of meninges
Dura mater – outermost meninx; double-layered, lines internal surface of cranium and is operated from the Arachnoid mater by the SUDURAL space
Arachnoid mater – middle meninx separated from the underlying pia mater by the SUBARACHNOID space. Web-like extensions from the arachnoid mater to the subarachnoid space gives this meninx its name
( Arachnida = spider family)
Pia mater – innermost meninx that clings to the surface of the brain
42
Which meninx is double-layered?
Dura Mater
43
CSF is located in one area outside the brain and four areas inside the brain – name these areas.
Both Lateral ventricles, Third ventricle, and Fourth ventricle
44
Location of the subarachnoid space
between the arachnoid mater and the pia mater
45
Location of the two lateral ventricles
both cerebral hemispheres
46
Location of the interventricular foramen
connected to the two lateral ventricles
47
Location of the third ventricle
in the diencephalon
48
Location of the cerebral aqueduct
connect the third and fourth ventricle
49
Location of the fourth ventricle
in the brain stem
50
Name the 4 regions of the adult brain
Cerebrum, Diencephalon, Brainstem, and Cerebellum
51
gyrus
Surface marked by elevated ridges
precentral gyrus- motor control area, left one controls right body movement and vise vera
postcentral- somatosensory area
52
sulcus
surface marked by shallow grooves, separates each cerebral hemisphere into lobes
53
fissure
Surface marked by deeper grooves
54
gray matter
matter made up by cell bodies and dendrites, unmyleinated axons, many makes up cerebral cortex
55
white matter
deep to the cerebral cortex; composed of tracts with myelinated axons which have a “whitish” appearance
56
commissural tracts
Commissures – connect corresponding areas in the two cerebral hemispheres, Corpus callosum is a commissure that connects the right and left cerebral hemispheres
57
projection tracts
connect the cerebrum to lower brain areas and the spinal cord. 2 types: Descending projection tracts send information from the cerebral cortex and Ascending projection tracts that send sensory information up to the cerebral cortex
58
association tracts
connect areas within the same cerebral hemisphere
59
What type of tract is the (a) corpus callosum (b) arcuate fasciculus (c) pyramidal tract?
a. commissural tracts
b. association tracts
c. projection tracts
60
What is the longitudinal fissure?
divides the cerebrum into right and left cerebral hemispheres
61
What is the corpus callosum?
holds the two 2 cerebral hemispheres together medially
62
Name the 5 lobes in each cerebral hemisphere
Frontal lobe
Temporal lobe
Parietal lobe
Occipital lobe
Insula
63
Which lobe cannot be viewed on the external surface of the cerebral hemisphere? Name the primary sensory cortex located in this lobe.
Insula because its located deep to the lateral sulcus.
Has the Gustatory Cortex
64
Name the sulcus that separates the frontal lobe and the parietal lobe in each cerebral hemisphere
Central Sulcus
65
What is the name of the gyrus just in front of the central sulcus – what is the significance of this gyrus?
PRECENTRAL GYRUS- contains the motor control area
66
What is the name of the gyrus just behind the central sulcus – what is the significance of this gyrus?
POSTCENTRAL GYRUS- contains the somatosensory area
67
The 3 functional areas of the cerebral cortex are motor areas, sensory areas and association areas. Which functional areas are located exclusively in the frontal lobe?
motor areas- primary motor cortex, Premotor cortex, Broca’s area, frontal eye field
68
Name and discuss the functions of each of the 4 motor area
primary motor cortex- in both right n left hemisphere, in pre central gyrus, Controls the voluntary movements of skeletal muscles; located in the precentral gyrus of the frontal lobe in each cerebral hemisphere where the large neurons called PYRAMIDAL CELLS are located. The axons of the pyramidal cells bundle to form the PYRAMIDAL or CORTICOSPINAL TRACTS which cross over on the ventral side of the medulla oblongata
premotor cortex- in both hemispheres, controls learned motor skills that are patterned or repetitive in nature such as typing, driving, playing an instrument
broca’s area- only in left hemisphere, Arcuate fasciculus connects the Broca’s area to the Wernicke’s area located in the left temporal lobe for language comprehension and expression, controls skeletal muscles involved in speech production hence, referred to as the “motor speech area”. Present in only the frontal lobe in the left cerebral hemisphere
frontal eye field- in both hemispheres, controls voluntary movements of the skeletal muscles that position the eyes called the extrinsic eye muscles
69
What is the consequence of:
a. damage to the precentral gyrus in the left frontal lobe in the left cerebral hemisphere?
b. damage to the pyramidal tracts in the left frontal lobe in the left cerebral hemisphere
BEFORE decussation?
c. damage to the left pyramidal tracts AFTER decussation?
d. damage to the precentral gyrus in the right frontal lobe in the right cerebral hemisphere?
e. damage to the pyramidal tracts in the right frontal lobe in the right cerebral hemisphere BEFORE decussation?
f. damage to the right pyramidal tracts AFTER decussation?
g. damage to the right postcentral gyrus in the right parietal lobe in the right cerebral hemisphere?
h. damage to the left postcentral gyrus in the left parietal lobe in the right cerebral hemisphere?
a. right side paralysis, speech problems, become slow, language memory deficients
b. idk
c. idk
70
Which motor area is typically found only in the left frontal lobe in the left cerebral hemisphere?
broca's area
71
Which area is known as the “motor speech area”?
broca's area
72
What is the function of the premotor cortex?
in both hemispheres, controls learned motor skills that are patterned or repetitive in nature such as typing, driving, playing an instrument
73
What is the function of the frontal eye field?
in both hemispheres, controls voluntary movements of the skeletal muscles that position the eyes called the extrinsic eye muscles
74
What happens to the movement of both eyes when the left frontal eye field is damaged?
you won't be able to move your right eye
75
What is the significance of the precentral gyrus in each cerebral hemisphere?
give motor control to both sides of your body
76
What are the pyramidal cells and where are they located?
bundle together to make PYRAMIDAL or CORTICOSPINAL TRACTS which cross over on the ventral side of the medulla oblongata (DECUSSATION OF THE PYRAMIDS) this sends singles to voluntary skeletal muscle, located in ocated in the precentral gyrus
77
What is the consequence of the “Decussation of the Pyramids”? Where does it occur?
the pyramid tracts cross over from sone side of the brain to the other. This makes it so your left primary motor cortex controls the right side of your body, happens in the precentral gyrus
78
Discuss the contralateral control of voluntary skeletal muscle movements by the cerebral cortex.
Right cortex controls left side of Brian and vise versa
79
What is Broca’s aphasia? What is Wernicke’s aphasia?
Broca’s aphasia- Damage to the Broca’s area in the left frontal lobe, haracterized by partial or complete loss of the ability to speak but language comprehension is intact
Wernicke’s aphasia- Damage to the Wernicke’s area in the left temporal lobe, characterized by loss of language comprehension and incoherent (nonsensical) speech to questions referred to as “word salad”
80
Explain why Broca’s aphasia and Wernicke’s aphasia are typically presented with right-side paralysis and not left-side paralysis
They present right side paralysis instead of left because of the Decussation of the Pyramid tracts
81
What is the consequence of damage to the right postcentral gyrus? What is the consequence of damage to the left postcentral gyrus?
right- sensory loss on left side
left- sensory loss on right side
82
Name the 3 main cerebral basal nuclei; discuss their function
Caudate nucleus, Putamen, and Globus pallidus
Function: initiating and stopping voluntary skeletal muscle movements; they inhibit unnecessary movements
83
What is the pathogenesis of Parkinson’s disease? With your understanding of the pathogenesis of PD, explain why L-DOPA is used instead of dopamine in the management of Parkinson’s disease (PD)
loosing function of Basel nuclei causes Parkinson's disease, we use L-DOPA because dopamine cannot get past the Blood-Brain Barrier
84
Which area in the diencephalon is referred to as the “Gateway to the cerebral cortex” and why?
Thalamus because its a relay station for sensory inputs to the cerebral cortex
85
What is the function of the lateral geniculate nucleus (LGN)?
Visual relay center in the thalamus
86
What is the function of the medial geniculate nucleus (MGN)?
auditory relay center in thalamus
87
Name structure in the diencephalon that acts as an endocrine gland
Hypothalamus secretes 9 hormones
88
What is the function of the hormone melatonin?
Induces sleep
89
Name the ventricle located in the diencephalon
the third ventricle, Epithalamus forms the roof of it
90
Structurally, how is the arrangement of the white matter and gray matter in the brainstem similar to the spinal cord
white matter on outside grey matter on inside
91
Structurally, how is the arrangement of the white matter and gray matter in the brainstem different from the cerebrum
brainstem: white matter on outside grey matter on inside
cerebrum: outer gray cortex, inner white matter with a pattern that resembles the branching tree
92
Name the 3 parts of the brainstem
Midbrain, pons, medulla oblongata
93
Name the ventricle located in the brainstem
the fourth ventricle
94
Which parts in the brainstem contain respiratory centers
pons and medulla oblongata
95
Where do the pyramidal tracts decussate?
ventral surface of medulla oblongata
96
Name and give the functions of the 2 pigmented nuclei in the midbrain
i) Red nuclei regulate limb flexion
ii) Substantia nigra contains dopamine-releasing neurons (=dopaminergic neurons) which project and modulate activities of the basal nuclei
97
The axons of the dopaminergic neurons in the substantia nigra project to what structures in the cerebrum?
basal nuclei
98
Discuss the pathogenesis of Parkinson’s disease
degeneration of the dopaminergic neurons from the substantia nigra to the basal nuclei
99
Where are the corpora quadrigemina located?
all four are in midbrain
100
What is the function of the superior colliculi?
both superior colliculi act as the visual reflex centers
101
What is the function of the inferior colliculi?
both inferior colliculi act as auditory reflex centers
102
How many of the 12 cranial nerves have their cell bodies located in the brain stem?
10
103
Explain why trauma to the brain stem can be fatal
There are specific cranial nerves in brainstem needed for living
104
In the cerebellum, what is known as the “Arbor Vitae?
inner white matter with a pattern that resembles the branching tree
105
What is the vermis?
the vermis holds the 2 cerebellar hemispheres together medially
106
Why is the vermis analogous to the corpus callosum?
both connect the two hemispheres of their respective structures
107
Name the cerebellar lobe that cannot be viewed on the surface of the cerebellum
Flocculonodular lobe
108
What is the major function of the cerebellum?
processes information from cerebral motor areas, visual and equilibrium inputs; smooth and coordinated skilled voluntary skeletal muscle movements. For equilibrium/maintenance of balance
109
The tandem walk test involves walking in a straight line with one foot immediately in front of the other (heel to toe) – the inability to maintain balance during a tandem walk due to alcohol intoxication is indicative of impairment of which brain region?
cerebellum
110
Describe the arrangement of the gray matter and the white matter (compare this arrangement to the brain stem; compare to the cerebrum and cerebellum)
outer white matter and an inner gray matter
this is similar to the brainstem:
brainstem: white matter on outside grey matter on inside
but different from cerebellum and cerebrum
cerebellum and cerebrum: outer gray cortex, inner white matter
a pattern that resembles the branching tree is also in cerebellum
111
spinal dural sheath
Dura mater, the outermost meninx is single-layered
112
conus medullaris
cone-shaped structure that ends spinal cord
113
filum terminale
fibrous extension of the pia mater from the conus medullaris and anchors the spinal cord vertically to the coccyx
114
denticulate ligaments
spinal cord is anchored laterally which is formed by Pia mater
115
epidural space
space between the spinal dural sheath and the internal surface of the vertebral column
116
subarachnoid space
space between the arachnoid mater and the pia mater, contains Cerebrospinal Fluid (CSF)
117
central canal
in the core of the spinal cord and inside the subarachnoid space, main purpose is to contain Cerebrospinal Fluid (CSF)
CSF acts as a “liquid cushion”; provides nutrients; removes metabolic wastes
118
How do the dura mater and pia mater surrounding the spinal cord differ from the dura mater and the pia mater surrounding the brain?
dura mater- double-layered in brain but single layered in spinal cord, gap between dura mater and arachnoid mater is called SUDURAL space and called epidural space
pia mater- forms two extensions in spinal cord but not in brain
119
Which type of paralysis occurs when the spinal cord is transected above the cervical enlargement?
QUADRIPLEGIA = flaccid paralysis of all four limbs
120
Which type of paralysis occurs when the spinal cord is transected below the cervical enlargement but above the lumbar enlargement?
PARAPLEGIA = flaccid paralysis of the 2 lower limbs
121
How can you tell the difference between paralysis caused by damage at the level of the precentral gyrus in the frontal lobe in a cerebral hemisphere and damage at the level of the spinal cord?
Brian paralysis effects top and bottom of one side
Spinal cord paralysis effects either all limbs or just the bottom two
122
Describe the parts of the PNS:
- Afferent (sensory) division; Sensory receptors
- Efferent (motor) division: Somatic nervous system; Autonomic nervous system (ANS)
Afferent (sensory) division- subdivision of PNS, takes information from sensory receptors to CNS
Sensory Receptors-
Somatosensory receptors – tactile receptors for spatial discrimination
Photoreceptors – sensory receptors that respond to light energy
Photoreceptors in the retina are used in VISION
Mechanoreceptors – sensory receptors that respond to mechanical force such as touch, pressure, stretch or vibration
Mechanoreceptors called Hair cells in the ear are used in HEARING
Chemoreceptors – sensory receptors that respond to changes in chemicals in solution
Efferent (motor) division- receive info for CNS to Somatic nervous system- voluntary muscles and Autonomic nervous system- involuntary muscle and glands
123
Activation of which division of the Autonomic Nervous System causes
a) the Fight-or-flight response
b) dilation of the pupils?
c) constriction of the pupils?
d) bronchodilation?
e) generalized vasoconstriction?
a. sympathetic division
b. sympathetic division
c. parasympathetic division
d. sympathetic division
e. sympathetic division
124
What is the consequence of damage to the right postcentral gyrus? What is the consequence of damage to the left postcentral gyrus?
right- left side paralysis, loss of sensation on the LEFT side of the body
left- right side paralysis, Broca's aphasia (loss of speech), loss of sensation on the RIGHT side of the body
125
What will be the presentation of an individual with widespread damage in the left cerebral hemisphere involving the left frontal lobe, left postcentral gyrus, left temporal, and left occipital lobe?
range of impairments affecting motor control on right side, sensory perception on right side, language (Broca's aphasia), and vision
126
Name the 3 major parts of the eye
eye wall, humors, lens
127
Name and describe the 3 layers of the wall of the eye. Which layers are avascular? Which layer is highly vascularized?
fibrous layer- outer layer composed of tough dense fibrous CT, consists of 2 regions, is avascular
vascular layer- middle layer that’s highly vascularized, consists of 3 regions, posterior 5/6th is the choroid, middle ciliary body, anterior iris
sensory layer- Innermost layer of the eye wall, posterior wall of the eye, Sensory layer consists of the pigmented layer and the neural layer
128
Name the two parts of the fibrous layer. Name the most anterior part of the eye. Which structure is known as the “white” of the eye?
a. Cornea- the anterior 1/6th of fibrous layer allows light to enter the eye because it’s avascular and transparent
Sclera- maintains the shape of the eye, protects the eye and serves attachments sites for the extrinsic muscles of the eye
b. cornea
c. sclera
129
Name the 3 parts of the vascular layer. Which part forms the “colored part” of the eye. What is the pupil?
a. choroid, middle ciliary body, anterior iris
b. iris
c. central opening in the iris called the PUPIL
130
Name the two layers of the sensory layer. Which layer is the retina?
a. Pigmented layer and Neural layer
b. Neural layer
131
optic disc
a blindspot where optic nerve exits through posterior wall of eye
132
macula lutea
lateral to optic disc, contains mostly cones
133
fovea centralis
in center of optic disc, contains only cones and it’s used for hard focus
134
Name and give the location of the two humors in the eye. Discuss the functions of each humor
Aqueous humor- anterior chamber in front of the lens, supplies nutrients and oxygen to the lens and cornea; carries
away metabolic wastes; maintains intraocular pressure to support the
eyeball
Vitreous humor- posterior segment behind the lens, supports the posterior surface of the lens; pushes the neural layer against the pigmented layer; maintains the intraocular pressure
135
Humors
fluids in the body
136
Which type of humor in the eye is formed and drained throughout life? What is the function of the canal of Schlemm? What is glaucoma?
a. Aqueous humor
b. drains the Aqueous humor
c. when intraocular pressure rises causing damage to retina and the optic nerve
137
Which humor is viscous and supports the back of the lens?
Vitreous humor
138
What is myopia and what type of lens is used to correct myopia? What is hyperopia and what type of lens is used to correct hyperopia?
a. Myopia = nearsightedness – occurs when distant objects are focused in front of the retina; eyeball too long, concave lenses to correct this
b. Hyperopia = farsightedness – occurs when light from close objects are focused behind the retina; eyeball too short, convex lenses to converge the light onto the retina
139
The sensory layer is double-layered – name the two layers
Pigmented layer and Neural layer referred to as the RETINA
140
Discuss the functions of the cells in the pigmented layer of sensory layer
single layer of cells which provide nutrients to the neural layer; contain melanin which absorbs light and prevents it from scattering; contain vitamin A required for the synthesis of the light-absorbing pigment called RETINAL
141
Explain how retinal detachment can lead to blindness
retina is used for sight to the detachment of blood to these parts will stop them from working
142
Does damage to photoreceptors lead to permanent loss of vision? Explain
yes, photoreceptors are one of the main sight providers so loosing them will lead to permanent sight loss
143
The neural layer is also known as the retina - consists of 3 layers of neurons – name these neurons
PHOTORECEPTORS; Bipolar neurons; Ganglion cells
144
Name the two types of photoreceptors
rods and cones
145
Which type of photoreceptors responds in dim light? Which type of photoreceptors responds in bright light? Which type is more sensitive to light, cones or rods?
a. rods
b. cones
c. rods
146
State the trichromatic theory of vision
several colors are seen depending on which/how many of the three types of cones are activated
147
Trace the pathway of light through the eye from the cornea to the photoreceptors in the retina
begins with the cornea, where light first enters and is refracted. From there, it passes through the pupil, is focused by the lens, and travels through the vitreous humor before reaching the retina
148
Discuss phototransduction. Are the photoreceptors depolarized or hyperpolarized in light?
photoreceptors hyperpolarize in response to light exposure
149
The axons of which type of neurons in the retina form the optic nerve and generate/ transmit action potentials? What is composition of the optic tract?
a. Ganglion cells
b. axons from optic nerve
150
Indicate the type of blindness when the
- right optic nerve is damaged
- right optic tract is damaged
- right occipital lobe is damaged
a. loss of sight in right eye
b. left side of both eyes loss of sight
c. right side of right eye and left side of left eye are damaged
151
What do ependymal cells do in the CNS?
Circulate cerebrospinal fluid using cilia
152
Name and describe the 3 major parts of the ear. What is the function of the pinna?
a. External ( outer) Ear, Middle Ear, Internal ( inner) Ear = labyrinth
b. collect and channel sound waves into the ear canal, where the sound is further amplified and transmitted to the eardrum
153
Name in order (from the tympanic membrane) the 3 auditory ossicles in the middle ear
malleus, incus, stapes. (mis)
154
Name the ossicle in direct contact with the
a) tympanic membrane
b) oval window
a. malleus
b. stapes
155
Name the type of fluid within the
(a) bony labyrinth
(b) membranous labyrinth
a. PERILYMPH
b. ENDOLYMPH
156
Name the two membranous sacs in the vestibule
Utricle and Saccule
157
Give the location of the following equilibrium receptors: maculae and
cristae ampullare
a. vestibule
b. semicircular canals
158
What is the membranous duct in the cochlea?
organ of Corti
159
Describe the organ of Corti; give the location of the
(a) Basilar membrane
(b) supporting cells
(c) Hair cells
(d) Tectorial membrane
rests on a flexible membrane called the BASILAR MEMBRANE
all found within organ of corti
160
Name the mechanoreceptors for hearing
Supporting cells and HAIR CELLS
161
Does damage to hair cells lead to permanent hearing loss? Explain
yes because once we damage them we cannot fix or replace them
162
Trace the path taken by sound waves through the ear. What determines
Loudness? Pitch?
a. Pinna to external acquits meatus to tympanic membrane to ossicles to oval window to fluids in cochlear channels
b. loudness- greater the amplitude, greater the loudness
pitch- greater the frequency, greater the pitch
163
Give the location and function of
a) medial geniculate nucleus
b) inferior colliculi
c) Primary auditory cortex
a. in thalamus, auditory relay center
b. auditory reflex centers in the midbrain
c. in Temporal lobes, main area responsible for processing auditory information
164
Will damage to the left temporal lobe cause hearing loss in the left ear, right ear or both ears?
hearing loss in right ear
165
Which tract connects the cerebrum to the spinal cord and lower brain areas?
Projection
166
Which structure contains only cones and provides high focus?
Fovea centralis
167
What does 20/20 vision mean?
You can see clearly at 20 ft what a normal person can
168
What type of cells are the olfactory cells and why are they considered unique in humans?
unique neurons because they do not exhibit longevity - olfactory cells are replaced every 60 days by the differentiation of the basal cells
169
Does damage to olfactory cells lead to permanent loss of smell? Explain
no because these cells regenerate
170
What are the two criteria a chemical must meet for olfactory processing to occur?
i) chemical must be volatile (gaseous) so it can be inhaled
ii) inhaled gas must be soluble in the thin coat of mucus covering the olfactory hairs ( cilia)
171
Axons of which neurons form
(a) olfactory nerve?
(b) olfactory tract?
a. cranial nerve 1
b. mitral cells
172
What is the role of the mammillary bodies in the processing of olfaction?
Impulses are also transmitted to the mammillary bodies, emotional aspect of smell
173
Name the two types of cells in a taste bud? What type of cell is the gustatory cell?
i) basal cells
ii) Gustatory cells = CHEMORECEPTORS
174
Does damage to gustatory cells lead to permanent loss of taste? Explain
no because they are replace every 7 days
175
Name the types of papillae that contain taste buds
Fungiform papillae: These are mushroom-shaped and located on the tip and sides of the tongue
Circumvallate papillae: These are large, circular papillae located at the back of the tongue
Foliate papillae: These are leaf-shaped papillae located on the sides of the tongue
176
Name the 3 cranial nerves that carry taste information. Name the gustatory relay center in the thalamus
a. facial nerve, Glossopharyngeal nerve, and Vagus nerve or CN 7, 9, 10
b. VENTRAL POSTEROMEDIAL NUCLEUS
177
In which cerebral lobe is the primary gustatory cortex located?
Insula
178
Which of the following statements is false regarding CSF and ventricles?
a. The lateral ventricles are separated by a thin membrane called the septum
pellucidum
b. The third ventricle is located in the cerebellum and connected to the
lateral ventricles via the cerebral aqueduct
c. CSF flows from the lateral ventricles through the interventricular foramen
to the third ventricle
d. Ependymal cells line the ventricles and help circulate CSF
- B - The third ventricle is not located in the cerebellum; it's in the diencephalon
- Connected to the lateral ventricles via the interventricular foramina
179
Which of the following is true regarding the sclera of the eye?
a. It is the anterior portion of the eye
b. It is avascular and transparent
c. It is the “white” of the eye
d. It helps maintain the shape of the eye and provides attachment sites for
the extrinsic muscles
e. It contains cones and rods
c and d
180
What is Multiple Sclerosis (MS)?
a. Autoimmune diseases that result in the demyelination of axons in the CNS
b. Causes the speed of nerve impulse transmission to decrease over time
i. Saltatory conduction -> continuous conduction
c. Interferes with the brain’s ability to communicate and control the body
i. Symptoms: paralysis, visual disturbances, mental changes,
depression
181
How do hormones and neurotransmitters differ in terms of their location of release and function within the body?
a. Hormones = chemical mediators released into the extracellular fluid
i. By endocrine glands
ii. Travel through the bloodstream to target cells throughout the body
iii. Slower, longer-lasting effect, and can affect distant tissues
b. Neurotransmitters - chemical messengers released into the synaptic cleft by neurons
i. Act locally at synapses to transmit signals between nerve cells,
leading to quicker, short-term effects
182
Compare and contrast the three classes of hormones. What are their primary differences in terms of structure and function? Which class is derived from amino acids, and which is derived from cholesterol?
Biogenic amines
i. derived from amino acids
ii. polar in nature, meaning they generally cannot pass through cell
membranes
iii. epinephrine and norepinephrine
b. Peptide/protein/glycoproteins
i. composed of amino acid chains
1. Some have a carbohydrate moiety
ii. Polar
iii. include hormones like insulin, oxytocin, and FSH
c. Steroid hormones
i. Nonpolar
ii. derived from cholesterol
iii. Hormones, such as testosterone, can pass through cell membranes
to bind with intracellular receptors
183
Discuss the potential causes of endocrine hyperfunction and hypofunction
a. Endocrine hyperfunction
i. Overproduction of a hormone
ii. could include tumors, autoimmune disorders, or excessive
stimulation from other hormones
iii. can cause symptoms like weight loss, nervousness, and fatigue
b. Endocrine hypofunction
i. Underproduction of a hormone
ii. conditions like hypothyroidism or Addison's disease
iii. can result from glandular destruction, genetic defects, or other
factors
iv. Symptoms can include fatigue, weight gain, and low blood pressure
184
What is an endocrine gland?
ductless glands the release chemical regulators called HORMONES directly into the extracellular fluid
185
Define negative feedback mechanism as it pertains to the actions of hormones
A hormone released in response to a stimulus (homeostatic imbalance) works via NEGATIVE FEEDBACK mechanism to maintain homeostasis, Negative Feedback Mechanism – the biological effects of hormones negate/eliminate/obliterate the stimuli that caused the release of the hormones
186
Name and discuss the 3 major stimuli for the release of hormones
187
Name and discuss the 3 classes of hormones; which class is derived from the amino acid tyrosine? Which class is derived from cholesterol?
a. Biogenic amine hormones, Peptide/protein/glycoproteins hormones, and Steroid hormones
b. Biogenic amine hormones
c. Steroid hormones
188
What are target cells for a hormone?
ACCESSIBLE, FUNCTIONAL receptors that the hormone binds to
189
Discuss the characteristics of hormone receptors. Do hormones bind to hormone receptors in an irreversible or reversible manner?
a. all hormone receptors are protein
b. these binds are reversible
190
There are two types of hormone receptors – membrane receptors and intracellular receptors - discuss which class/classes of hormones bind/s to each type of receptors.
membrane receptors- bind polar hormones like Biogenic amine hormones and Peptide/protein/glycoproteins hormones
intracellular receptors- bind to non polar like steroid hormones
191
Do polar hormones bind to intracellular receptors? Explain
no because the polar hormones cannot go through plasma membrane to get to intracellular receptors
192
Name and discuss the 4 types of hormone INTERACTIONS with receptors. Can agonism result in the hyperfunction of a hormone?
Classical Endocrine Interaction – endocrine gland releases a hormone into the bloodstream which transports the hormone to its target cells
Paracrine Interaction – endocrine cells release hormone into interstitial fluid surrounding the neighboring target cells
Juxtacrine Interaction – endocrine cells are juxtaposed to the target cells in the same organ hence, as the endocrine cells release hormone, the hormone interact directly with its target cells
Autocrine Interaction – the endocrine cells releasing the hormone acts as target cells for the hormone
Yes, because you will have hormones being release without the release of their stimuli
193
Name and discuss the 5 types of hormonal INTERRELATIONSHIPS. Can permissiveness result in the hyperfunction of a hormone?
Agonism – a hormone binds to the receptors of another hormone and mimics the biological effects of that hormone
Antagonism – a hormone binds to the receptors of another hormone blocking the hormone from binding to its own receptors; No biological effects of that hormone observed
Permissiveness – the biological effects of a hormone (bound to its own receptors), increases the levels of another hormone and/or increases the number of receptors of that hormone resulting in the overall increase in the biological effects of that hormone
Cooperativity – hormones work in in tandem on the same target tissue to bring about a desired biological effect
Synergism – a group of hormones affects a target tissue simultaneously to bring about a biological response greater than the sum of the individual hormonal effects
194
Discuss possible causes of endocrine hyperfunction. Discuss possible causes of endocrine hypofunction
a.
-Tumor of endocrine gland
-Ectopic production of hormones
-Exogenous intake (iatrogenic)
-Block in degradation
-Stimulatory antibodies
-Stimulation of the signal transduction mechanism
-Destruction of endocrine gland releasing sequestered hormones
-Agonism by another hormone
b.
-Destruction of the endocrine gland
-Defects in the biosynthetic pathway of a hormone
-Prevention of the conversion of prohormone to the active hormone
-Stimulation in the degradation of a hormone
-Down regulation of hormone receptors – receptors not accessible
-Receptor blockade - antagonism by another hormone at the receptors
-Defects in the signal transduction mechanism
-Damage to the target tissues
195
Which two hormones synthesized by the hypothalamus travel by the tract into the posterior pituitary for storage and release? Is the posterior pituitary considered an endocrine gland?
Oxytocin and Antidiuretic Hormone (ADH)
posterior pituitary is part of the pituitary gland which is a endocrine gland
196
Will high levels of ADH cause increase in blood volume or increase in urine volume? Explain
Will low levels of ADH cause increase in blood osmolality or increase urine osmolality? Explain
High ADH:
→ Causes increased water reabsorption in the kidneys → increased blood volume and decreased urine volume.
Low ADH:
→ Causes decreased water reabsorption → increased urine volume and increased blood osmolality (more concentrated solutes in blood due to water loss)
197
Name the seven hormones synthesized by the hypothalamus that travel by the portal system into the anterior pituitary. Give one function of each hormone
TRH (Thyrotropin-releasing hormone) Stimulates release of TSH
CRH (Corticotropin-releasing hormone) Stimulates release of ACTH
GnRH (Gonadotropin-releasing hormone) Stimulates release of LH and FSH
GHRH (Growth hormone-releasing hormone) Stimulates release of GH
GHIH (Somatostatin) Inhibits release of GH and TSH
PIH (Prolactin-inhibiting hormone, aka dopamine) Inhibits release of prolactin
PRH (Prolactin-releasing hormone) Stimulates release of prolactin
198
Does hypothyroidism cause weight gain or weight loss?
weight gain
199
Thyroid hormones are calorigenic hormones. Does hyperthyroidism or hypothyroidism cause cold intolerance? Explain
hypothyroidism
→ Because thyroid hormones are calorigenic (generate heat). Low levels reduce heat production
200
What type of pancreatic cells release insulin?
What is the major stimulus for insulin release?
Will the actions of insulin increase or decrease the blood glucose levels?
Pancreatic cells: Beta cells
Stimulus: High blood glucose
Effect of insulin: Decreases blood glucose by promoting uptake into cells and storage as glycogen
201
What type of pancreatic cells release glucagon?
What is the major stimulus for glucagon release?
Will the actions of glucagon increase or decrease the blood glucose levels?
Pancreatic cells: Alpha cells
Stimulus: Low blood glucose
Effect of glucagon: Increases blood glucose by stimulating glycogen breakdown and glucose release by the liver
202
Will high levels of cortisol cause hypoglycemia or hyperglycemia? Does cortisol act like insulin or glucagon?
High cortisol: Causes hyperglycemia
Cortisol acts more like glucagon — it increases blood glucose via gluconeogenesis and reduces glucose uptake in cells
203
What are the stimuli for aldosterone release? If a hormone is released in response to low Na+ and high K+ levels in the blood, will this hormone act by stimulating Na+ excretion and K+ reabsorption? Explain
Stimuli for aldosterone release:
Low Na+, high K+, and low blood pressure (via the renin-angiotensin system)
Will it stimulate Na+ excretion and K+ reabsorption?
No. It will do the opposite:
→ Stimulates Na+ reabsorption and K+ excretion
→ This helps retain sodium and water (increasing blood pressure) and eliminate excess potassium
