Chapter 3.4-3.6 Flashcards

1
Q

Define CNS and PNS

A

CNS: brain and spinal chord; a great majority of neuronal cell bodies are found in here
PNS: includes all axons dendrites and cell bodies

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2
Q

Nuclei versus ganglia

A

Nuclei: bundle of nerve cell bodies in the CNS
Ganglia: bundle of nerve cell bodies in the PNS

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3
Q

What are the three subdivisions of the brain?

A

Hindbrain ( rhomboencephalon)
Midbrain ( Mesencephalon)
Forebrain ( Prosencephalon)

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4
Q

CSF Cerebrospinal fluid

A

A clear liquid that the entire CNS floats in. Serves various functions such as shock absorption and exchange of nutrients and waste with the CNS.

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5
Q

Spinal chord : Location, General Function

A

Spinal chord is connected to the brain and protected by the CSF and the vertebral column. Pathway for info to and from brain. Most sensory data is relayed to brain for info, but the SC is also a site for info integration.
General: Simple reflexes

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6
Q

What is the hindbrain consisted of?

A

Medulla, pons and cerebellum

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7
Q

Medulla: Location, General Function

A

Location: Below the pons and is the area of the brain which connects to the spinal chord
General : Involuntary functions

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8
Q

Pons : Location, General Function

A

Location: Below midbrain and above the medulla , connection point between brain stem and the cerebellum
General: Relay centre and balance

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9
Q

Cerebellum : Location, General Function

A

Location: behind the pons and below the cerebral hemispheres
General: Movement coordination

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10
Q

Damage to cerebellum

A

Results in poor hand eye coordination and balance

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11
Q

Midbrain: Location, General Function

A

Location: Above the pons and below the hypothalamus
General: eye movement

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12
Q

Brainstem consists of :

A

Medulla, pons, midbrain

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13
Q

Forebrain includes:

A

Diencephalon and telencephalon

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14
Q

Diencephalon consists of:

A

Thalamus and hypothalamus

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15
Q

Thalamus : Location, General Function

A

Location: Near the middle of the brain below the cerebral hemispheres and above the midbrain.
General: Integrating center and relay station

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16
Q

Hypothalamus: General Function

A

General: Homeostasis and behavior

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17
Q

Telencephalon: what makes it special

A

-Consists of two separate cerebral hemispheres, which is unlike all of the other parts of the CNS up to and including the diencephalon ( which forms a single symmetrical stalk)

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18
Q

Left and R hemispheres and what they are responsible for

A

L hemi: primarily controls motor functions of the right side of the body; generally responsible for speech, dominant in most people
R hemi: controls motor functions of L side of the body; generally responsible for visual spatial reasoning and music

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19
Q

Corpus Callosum

A

A thick bundle of axons which connect the cerebral hemispheres

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20
Q

Cerebrum

A

Largest region of human brain and consists of the L paired cerebral hemispheres.

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21
Q

Hemispheres of cerebrum consist of:

A
  • cerebral cortex ( outer layer of gray matter) plus an inner core of white matter connecting the cortex to the diencephalon
  • gray matter: composed of trillions of somas
  • white matter: composed of myelinated axons
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22
Q

Cerebral hemi general function

A

conscious thought processes and intellectual function

play a role in processing somatic sensory and motor info

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23
Q

The cerebral cortex is divided into 4 lobes:

A

Temporal, Frontal, Parietal, Occipital

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24
Q

Frontal lobe

A

initiate all voluntary movement and are involved in complex reasoning skills and problem solving

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25
Parietal lobes
involved in general sensation ( such as touch, temp, pressure, vibration, etc) and in gustation ( taste)
26
Temporal lobes
-process auditory and olfactory sensation and are involved in short term memory, language comprehension, and emotion
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Occipital lobes
Process visual sensation
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Frontal eye field
Controls learned eye movements
29
Broca's A general function
speech production
30
Wernicke's A general function
language comprehension
31
Basal nuclei : General Function
- composed of gray matter and are located deep within the cerebral hemispheres; consists of several functioning divisions General: Movement
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Limbic system: Location, General Function
Location: between the cerebrum and diencephalon - includes substructures such as the amygdala , cingulate gyrus and hippocampus -works closely with parts of cerebrum, diencephalon, and midbrain General: Emotion, memory and learning
33
Basal nuclei and cerebellum
process and coordinate mvmt initiated by the primary motor cortex; basal nuclei are inhibitory ( prevent excess movement) whereas cerebellum is excitatory
34
Cerebral cortex : General Function
General function: Perception, skeletal muscle mvmt, memory, attention, thought, language and consciousness
35
motor and sensory regions of the cortex are organized such that:
a particular small A of the cortex controls a particular body part, a larger A is dedicated to a body part which requires more and more sensation
36
All neurons entering and exiting the CNS are:
carried by 12 pairs of cranial nerves and 31 pairs of spinal nerves
37
Cranial vs. Spinal nerves
Cranial: convey sensory and motor info to and from the brainstem Spinal: convey sensory and motor info to and from the spinal chord
38
Vagus nerve: Effects
- decreases heart rate and GI tract activity - part of the parasympathetic division of the autonomic nervous system - consists of a bundle of axons that end in ganglia on the surface of the heart, stomach and other visceral organs; the axons consisting of the vagus nerve are pregang and come from somas in the CNS - on surface of heart and stomach, they synapse with posting
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Somatic motor neurons
All innervate skeletal muscle cells, use ACh as neuro, cell bodies in brainstem or ventral ( front) portion of the spinal cord
40
Somatic sensory neurons
All have long dendrite extending from sensory receptor toward the soma, which is located just outside of the CNS in a dorsal root ganglion. All somatic sensory neurons, the first synapse is in CNS; depending on the type of sensory info conveyed, axon synapses in the cord or stretches al the way up to the brain stem before its first synapse
41
Dorsal root ganglion
- Bunch of somatic and autonomic sensory neuron cell does located just dorsal ( back of ) the spinal cord - Pair of dorsal root ganglia for every segment of the spinal cord, and thus the dorsal root ganglia, form a chain along the dorsal ( back) aspect of the vertebral column - Dorsal root ganglia are protected within vertebral column but r outside the meninges ( protective sheath of the brain and cord) and thus outside the CNS - An axon extends from the somatic sensory neurons soma into the spinal cord
42
Autonomic PNS efferents
Eff.ts of sympa and para systems consists of 2 neurons: pre and post
43
Preganglionic neuron
Cell body in the brainstem or spinal cord Sends axon to an autonomic ganglion , located outside the spinal column In the ganglion, axon synapses with postganglionic neuron
44
Postganglionic neuron
Sends an axon to an effector ( smooth muscle or gland)
45
All autonomic pregang release
Acetylcholine as neuro
46
All parasympa postgang neurons release
Acetylcholine as neuro
47
Sympa postgang neurons release
norepinephrine NE as their neuro
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Location of preganglionic soma for syma
Almost all have cell bodies in the thoracic (chest) or lumbar ( lower back ) regions of the spinal cord Therefore, they are located at the thoracolumbar region
49
Location of pregang soma for parasympa
Cell bodies in the brain stem ( head or cranium) or sacral portion ( lowest portion of the spinal cord)
50
Sympa Pre and Post gang length
Pre- short | Post- long
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para pre and post gang length
pre - long | post - short
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Ganglia sympa
only a few ganglia sympa ganglia are quite large far from effector, close to cord
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Ganglia para
small ganglion, close to effector, far from cord
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Auto afferent ( sensory ) vs Somatic afferent
Similar except auto can synapse in PNS at auto ganglia with auto efferent neurons in what is known as a short reflex whereas the first synapse of somatic aff.t neurons is in the CNS
55
Adrenal cortex location and hormones released
``` Outer portion of adrenal gland- cortex secretes glucocorticoids ( cortisol) mineralocorticoids ( aldoseterone) and some sex hormones ```
56
Adrenal medulla location, relaton to autonomic , hormone relased
Inner portion of adrenal gland - medulla Part of sympa system embryologically derived from sympa postgang and directly innervated by sympa pregang.c neurons Upon activation of sympa , adrenal gland is stimulated to release epinephrine , which is also known as adrenaline
57
Epinephrine: derivatives, effects
Slightly modified version of norepinephrine, neuro released by sympa postgang Epi is hormone because released into blood by ductless gland Behaves like neuro because it elicits effects very rapidly and effects are quite short lived Causes sudden flushing and sweating one experiences when severely startled, stimulation of heat
58
Sensation , sensory receptors
Sensation: process by which we received info from the world around us Sensory receptors; detect data both internally and externaly and send it to the CNS for processing
59
Sensation vs. Perception
Sensation: act of receiving info Perception: act of organizing, assimilating, interpreting sensory input into useful and meaningful info
60
How does the brain know the diff between stimulation of visual receptors and olfactory receptors?
Both signals are received in the brain as action potentials from sensory neurons. Brain distinguishes sensory stimuli based on which sensory neurons are signaling.
61
Exteroreceptors | Interoceptors
Ex: sensory receptors that detect stimuli from the outside world In: receptors that respond to internal stimuli
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Mechanoreceptors
respond to mechanical disturbances
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Mechanoreceptor ex: pacinian corpuscles
pressure sensors located deep in the skin shaped like an onion and composed of concentric layer of specialized membranes when corpuscular membranes are distorted by firm pressure on the skin, nerve endings become depolarized and signal travels up the dendrite ( these are graded potential changes- not action potentials)
64
Graded potential changes vs Action potentials
Action potentials, once initiated, are all or nothing events Graded potentials code info based on amplitude, They are initiated by a stimulus that vary in magnitude depending on strength of the stimulus
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Auditory hair cell vs. vestibular cells
Mechano Auditory: specialized cell in cochlea of the inner ear Vestibular: in special organs called semicircular canals,, also found in th inner ear Role is to detect acceleration and position relative to gravity
66
Chemoreceptors | Ex
Respond to particular chemicals Olfactory: detect airborne chemicals and allow us to smell things Gustatory: taste buds Auto: in walls of carotid and aortic arteries respond to changes in arterial pH , pCO2, pO2 levels
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Nocireceptors and ex
Pain receptors, stimulated by tissue injury consist of free nerve ending that detects chemical signs of damages can be auto or somatic
68
Autonomic pain receptors
Do not provide the conscious mind with clear pain info, but they frequently give sensation of dull aching pain create illusion of pain on skin, when their nerves cross paths with somatic afferents from the skin , phenomenon known as referred skin
69
Thermoreceptors and 3 categories of thermo
stimulated by changes in temp autonomic and somatic ex cold sensitive, warm sensitive and thermal nociceptors ( detect painfully hot stimuli)
70
Electromagnetic receptors and ex
stimulated by electromagnetic waves in humans, rods and cones of the retina of the eye in other animals, electro and magneto r separate ex: some fish detect electric fields with electroreceptors and magnetoreceptors allow animals to sense the earths magnetic field, which can help them navigate during migration
71
Four properties that need to be communicated to the CNS:
Stimulus modality, location, intensity, duration
72
Stimulus modality
Type of stimulus, CNS determines his based on the type of receptor that is firing
73
Stimulus intensity
Coded by frequency of action potentials
74
Dynamic range
Range of intensities that can be detected by sensory receptors, can be expanded by range fractionation
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Range fractionation and ex
Including multiple groups of receptors with limited ranges to detect a wider range overall ex: in human cone cells which respond to different but overlapping ranges of wavelengths to detect the full visual spectrum of light
76
Stimulus location
communicated by receptive field of sensory receptor sending signal
77
Improving localization of stimulus
Overlapping receptive fields of neighboring receptors works like a venn diagram allows the brain to localize a stimulus activating neighboring receptors to the A where the receptive fields overlap
78
Discrimination between 2 stimuli
improved by lateral inhibition of neighboring receptors
79
Stimulus duration
can be coded explicitly or not
80
Tonic receptors
fire action potentials as long as stimulus continues however, these are subject to adaptation , and the frequency of action potentials decreases as stimulus continues at the same level explicitly communicates the duration of stimulus
81
Phasic receptors
only fire action potentials when stimulus begins do not explicitly communicate the duration of the stimulus important for communicating changes in stimuli and essentially adapt immediately if stimulus continues at the same level
82
Adaptation
decrease in firing frequency when intensity of stimulus remains constant allows the brain to tune out unimpt info from the environment receptors do not stop being able to respond, they can still be triggered if the stimulus intensity increases
83
Nervous system is programmed to respond to
changing stimuli because constant stimuli are not a threat whereas changing stimuli need to be dealt with nociceptors do not adapt under any circumstance, because pain something that the nervous system wants us to do something about
84
Propioception
awareness of self and body position | also known as kinesthetic sense
85
Muscle spindle
important ex of a propioceptor , mechanoceptor sensory organ specialized to detect mucle stretch receptor that senses muscle stretch in the muscle stretch reflex
86
Other proprioceptors: Golgi tendon organs and joint capsule receptors
Golgi: monitors tension in the tendons joint: detect pressure, tension and movement in the joints
87
Purpose of proprioceptive system
Allow us to know positions of our body parts by monitoring the activity of the musculoskeletal system Important during activity when precise feedback needed for coordinated motion
88
Which portion of CNS do you expect to require input from proprioceptors?
Cerebellum, which is responsible for motor coordination
89
Gustation | Olfaction
gust: taste olf: smell
90
Gustation process
Taste bud consists of specialized epithelial cells shaped like an onion In centre of taste bud is a taste pore, with taste hairs which detect food chemicals Info about taste is transmitted by cranial nerves to an A of brain in temporal lobe not far from where brain receives olfactory info
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Taste buds
``` Can only distinguish 5 different flavors sweet ( glucose) salty ( Na+) bitter ( basic) sour ( acidic) umami ( amino acids and nucleotides) ```
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Olfaction process
Accomplished by olfactory receptors in the roof of the nasopharynx Receptors detect airborne chemicals which dissolve in the mucus covering the nasal membrane Olfactory nerves project directly to olfactory bulbs of the brain
93
Olfactory bulbs
Located in temporal lobe of the brain near the limbic system, important for memory and emotion Might explain why certain smells can bring back vivid memories or feelings
94
Pheromones
chemical signals which cause a social response in members of the same species, not well understood in humans, but have been studied extensively in insects important means of communicating info; ex. alarm pheromones alert rest of beehive of danger
95
Outer ear structures
Auricle or pinna | External auditory canal
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Division of middle and outer ear
Tympanic membrane or eardrum
97
Middle ear structures
``` Consists of the ossicles Three small bones called: malleus ( hammer) incus ( anvil) stapes ( stirrup) ```
98
Division of middle and inner ear
oval window
99
Structures of inner ear
cochlea semicircular canals utricle saccule
100
Semicircular canals with utricle and saccule
Important for a sense of balance
101
Membrane covered hole in cochlea near oval window and function
round window | releases excess pressure
102
Eustacian tube / auditory tube
Passageway from the back of throat to the middle ear functions to equalize pressure on both sides of the eardrum and is the cause of ear popping 1 experiences in high altitudes or underwater
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Mechanism of hearing
Sound waves enter external ear and pass into auditory canal- cause eardrum to vibrate malleus receives vibrations and pass to incus and stapes stapes contacts the oval window and vibration oval window creates pressure waves in perilymph and endolymph fluids in cochlea pressure waves in endolymph cause vibration of basilar membrane basilar membrane is covered with auditory receptor cells called hair cells cells have cilia projecting from apicall surfaces which contact the tectorial membrane when the basilar membrane moves , hairs dragged across tectorial mem and they bend displacement opens ion channels in hair cells, which results in neuro release dendrites from bipolar auditory afferent neurons are stimulated by neuro and thus the sound vibrations are converted to nerve impulses
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Organ of corti
basilar membrane, hair cells and tectorial membrane | primary site at which auditory stimuli are detected
105
Reason why bones in middle ear arranged in such a way
They amplify the sound vibrations passing through the middle ear
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Sound vibrations pass thru before being sensed
first conveyed through the air then they are conveyed through bone then liquid before they are sensed
107
outer ear and middle ear
convey sound waves to the cochlea
108
PItch
Frequency of sound is distinguished by which regions of the basilar mem vibrate, stimulating different auditory neurons
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Basilar membrane thickness
Varies | Thick near oval window and gradually becomes thin and floppy near the apex
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Low frequency | High frequency
Low: long wavelength, stimulated hair cells at the apex of the cochlear duct High: short wavelength, stimulate hair cells at the base of the cochlea, close to oval window
111
Loudness of sound
distinguished by the amplitude of vibration | louder sounds cause more frequent action potentials in the auditory nerve
112
Stereophonic hearing
Allowed for by having 2 ears
113
Determining the location of the sound
by the difference detected by the 2 ears ex. if a horn blasts to your right, right ear receives sound waves slightly sooner and slightly more intensely than the L ear
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If a sensory neuron leading from ear to brain fires an action potential more rapidly, how will the brain perceive this change?
More rapid firing of cochlear neuron indicates an increase in the volume of the sound If pitch is changed, a different set of neurons would fire action potentials
115
In some cases of deafness, sound can still be detected by conduction of vibration through the skull to the cochlea. If the auditory nerve is severed, can sound still be detected by conductance through bone?
Conductance through bone allows some hearing by causing the cochlea to vibrate, which stimulates action potentials that pass through the auditory nerve to the brain. However, if the auditory nerve is severed, no hearing of any kind is possible
116
If the bones of the middle ear are unable to move, would this impair detection of sound by conductance through bone?
Bones of the middle ear serve to conduct vibration from outer ear to liquid within the cochlea but are not involved in detecting sound. Bone conductance can still stimulate the cochlea and result in hearing if the middle ear is non-functional.
117
Vestibular complex
Made up of 3 semicircular canals: utricle, saccule and ampullae Monitors static equilibrium and linear acceleration, which contributes to your sense of balance
118
Semicircular canals
Tubes filled with endolymph, like cochlea, contain hair cells that detect motion Function is to detect rotational acceleration of the head Innervated by afferent neurons which send balance info to pons, cerebellum, and other areas
119
Cornea
Clear portion at the front of the eye Bends and refracts light as it passes through because the cornea is highly curved and acts like a lens , its refractive index is higher than that of air
120
Sclera
white layer that the cornea is continuous with at the borders
121
Choroid
Layer beneath the sclera | contains darkly pigmented cells which help absorb excess light within the eye
122
Retina
Layer beneath the choroid Surface where light is focused Detects light and converts stimuli to action potentials to send to the brain located at the back of the eye contains electromagnetic receptor cells ( photoreceptors) called rods and cones
123
Anteriror chamber
Just inside the cornea | Contains fluid called the aqueous humour
124
Iris
Membrane at the back of the ant chamber coloured part of the eye Muscles of the iris regulate the diameter of the pupil
125
¨Pupil
Opening in the iris
126
Posterior chamber
Behind the iris | Also contains aqueous humor
127
Lens
In the back part of the posterior chamber | Fine tune the angle of the incoming light so that beams are perfectly focused upon the retina
128
Ciliary muscle
varies the curvature and refractive power of the lens
129
Vitreous chamber
Where light passes thru on route to the retina from the lens
130
Passage of light in the eye
Cornea- anterior chamber- pupil - posterior chamber- lens-vitreous chamber- retina When passing through retina, pass through ganglion cells- bipolar cells before reaching cone and rod cells
131
Rods and cones
responsible for detecting light
132
Transmission of visual info
rods and cones synapse with nerve cells called bipolar cells ( 1 dendrite and 1 axon) bipolar cells synapse with ganglion cells, whose axons make u the optic nerve, which travels from each eye to occipital lobe of the brain for complex analysis of visual image
133
Optic disk
point on retina where many axons from ganglion cells converge to form the optic nerve also known as blind spot because it has no photoreceptors
134
Macula
oval shaped pigmented area near the center of the retina
135
fovea centralis
at the center of the macula contains only cones and is responsible for extreme visual acuity also called the focal point
136
visual acuity
sharpness of vision
137
Rods and cones are made up of:
special pigment proteins that change tertiary structure upon absorption of light
138
Opsin
Pigment protein in rods and cones | Each one is bound to 1 molecule of retinal and contains 1 molecule of retinal , which is derived from vit A
139
Dark rods and cones and retinal, bipolar cells
Dark: rods and cones are resting and retinal has several trans double bonds and 1 cis double bond retinal and opsin keep the Na channel open cell remains depolarized both rods and cones release Glu onto bipolar cells, preventing them from firing
140
Light rods and cones and retinal , bipolar cells
absorb light , retinal converted to all trans form series of reactions which closes Na channel, causing cell hyperpolarization rods and cones stop releasing Glu , bipolar cell depolarizes, causes depolarization of ganglion cells and an action potential along axon of ganglion cell
141
NIght vision
accomplished by rods, which are more sensitive to dim light and motion and more concentrated at periphery of the retina
142
Colour vision
require cones, which require abundant light and are also responsible for high acuity vision more concentrated at the fovea as a result three cones consist of colour vision, absorb blue, green and red light
143
What physical difference allows functional difference of cones?
Each type of cone makes a particular protein which is specialized to change conformation when light of appropriate frequency strikes it
144
Emmetropia
normal vision
145
Myopia
Nearsightedness too much curvature causes light to be bent too much and to be focused in front of the retina can be corrected by concave ( diverging) lens, which causes light to diverge slightly before they reach the cornea too much refraction at the lens or an abnormally long eyeball results in a focal length that is too short
146
Hyperopia
farsightedness focusing light behind retina caused by too little curvature can be corrected by convex (converging) lens , cauing light rays to converge before cornea too little refraction at the lens or an abnormally short eyeball results in a focal length that is too long
147
Presbyopia
inability to accommodate ( focus) | results from loss of flexibility of the lens, which occurs with aging
148
Neurons in visual cortex
fire in response to very specific info
149
Feature detecting neurons
specific neurons in the brain that fire in response to particular visual features, such as lines, edges, angles and movement info is passed along to other neurons that begin to assimilate these distinct feature into ore complex objects and so on
150
Feature detection theory
explains why a certain area of the brain is activated when looking at a face versus when looking at letters on a page
151
Parallel processing
many aspects of a visual stimulus ( such as form, motion, color and depth) are processed simultaneously instead of in a step by step fashion different stimuli used in order to vast amounts of information
152
Occipital lobe constructs
holistic image by integrating all of the separate elements of an object, in addition to accessing stored information ex. brain is simultaneously processing the individual features of an image, while also accessing stored info
153
Amount of the cortex dedicated to processing: visual info touch info auditory info
visual info: 30% touch info: 8% auditory: 3%
154
Depth perception
describes ability to see objects in 3D despite the fact that images are imposed on the retina in only 2D allows us to judge distance
155
Depth perception experiments
Visual cliff demonstrates that depth perception appears to be largely innate babies placed on clear glass surface above a steep drop off most babies not venture out over the visual cliff, indicating that their depth perception was developed enough to understand that the drop was dangerous
156
Binocular cues (BC)
depth cues that depend on info received from both eyes and are most important for perceiving depth when objects are close to us in our visual field
157
Retinal disparity
binocular cue brain compares the images projected onto 2 retinas in order to perceive distance greater difference or disparity between the 2 images on each retina, shorter the distance to the observer farther images have less disparity ( images on each retina are quite similar)
158
Convergence
binocular cue describes the extent to which eyes turn inward when looking at an object greater the angle of convergence or inward strain, the closer the object
159
Monocular cues
depth cues that depend on info available from either eye alone important for judging distances of objects that are far from us since the retinal disparity is only slight cannot rely on binocular cues for objects that are farther distances
160
relative size
if objects are assumed to be the same size, the one with smaller image on retina appears more distant MC
161
interposition
if one object blocks the view of another, we perceive it as closer MC
162
relative clarity
perceive hazy objects as more distant than sharp clear objects MC
163
texture gradient
change from coarse distinct texture to a fine indistinct texture indicates increasing distance MC
164
relative height
perceive objects higher on the visual field as farther away | MC
165
relative motion
MC | objects which are near to us appear to move faster than objects that are farther away
166
linear perspective
parallel lines appear to converge as distance increases greater convergence, greater distance MC
167
light and shadow
dimmer of two identical objects seems farther away MC closer objects reflect more light than distant objects
168
receptor , receptor type, organ , stimulus for interoception
``` receptor: aortic arch baroreceptors pH receptors receptor type: baroreceptor chemo receptor organ: aortic arch aortic arch or medulla oblongata Stimulus : blood pressure pH ```
169
Absolute threshold
minimum stimulus intensity required to activate a sensory receptor 50% of the time ( and thus detect the sensation) can vary between individuals and different organisms varies with age ex. as we get older, we gradually lose our ability to detect higher pitched sounds important for detecting the presence or absence of stimuli
170
What is the anatomical reason for the loss of our ability to detect higher pitched sounds as we age?
Loud sounds mechanically harm the hair cells , causing them to die When this occurs, hair cell can no longer send sound signals to the brain once hair cell dies in a human, it never regrows hair cells detecting higher frequency sounds are the smallest and most easily damaged, therefore as people age and more hair cells are damaged and lost, hearing loss occurs since the smallest hair cells are the ones most likely lost, loss of sensitivity to high pitched sounds is common in older people
171
Difference threshold
just noticeable difference or JND minimum noticeable diff between any 2 stimuli 50% of the time magnitude of initial stimulus influences the difference threshold
172
Webers law
states that two stimuli must differ by a constant proportion in order for their difference to be perceptible
173
Proportion 2 stim differ by in order to detect in humans for: weight light intensity tone frequency
weight: 2% light: 8% tone: 0.3%
174
Signal detection theory
attempt to predict how and when someone will detect presence of a given sensory stimulus ( signal) in presence of other sensory stimuli in the background ( the noise) 4 possible outcomes hit: signal present and detected miss: signal present but not detected false alarm: signal not present but person thought it was correct rejection: signal not present and person did not think it was
175
Gesalt
organized whole perceived as more than the sum of its individual parts when humans perceive an object, rather than seeing lines, angles, colors and shadows, they perceive the whole- a face, a table or dog gesalt principles can be applied to any sensory modality
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Emergence
Gesalt principle when attempting to identify an object, we first identify its outline, which then allows us to figure out what the object is only after the whole emerges do we start to identify the parts that make it up
177
Figure or ground
Gesalt principle describes perpetual tendency to separate the figure or object from everything else ( background) based on a number of variables like size, shadow, contrast, color, etc everything that is not figure is ground
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Multistability
gesalt principle of multistable perception | tendency of ambiguous images to pop back and forth between alternative interpretations in our brains
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Law of proximity
gesalt law of grouping things that are near each other seem to be grouped together nearby objects tend to be perceived as unit or group
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Law of similarity
gesalt law of grouping things that are similar tend to appear grouped together we perceive similar objects as a group or unit
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law of continuity
gesalt law of grouping law of good continuation we perceive smooth continuous line forms rather than disjoined one when their is an intersection between two objects, people tend to perceive each object as a single uninterrupted object
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Law of closure
gesalt law of grouping we perceive things as a complete logical entity because our brain fills in gaps in the information minds tendency to see complete figures or forms even if the picture is incomplete
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law of common fate
gesalt law of grouping | objects moving in same direction or moving in synchrony are perceived as a group or unit
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law of connectedness
things that are joined or linked or grouped together are perceived as connected
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bottom up processing
begins with sensory receptors and works up to the complex integration of info occurring in the brain also known as data driven processing use bottom up processing when we have no little prior experience with the stimulus
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Top down processing
occurs when brain applies experience and expectations to interepret sensory info instead of focusing on sensory input, we use our prior experience and knowledge to impose our expectations on the stimulus, which tends to occur with stimuli we are more familiar with
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Nervous system vs. Endocrine system : time taken to act length of the effects
NS is fast acting with relatively short term effects | endocrine system is slower at communicating signals but have generally longer lasting effects
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connection between nervous and endocrine
neurons can signal the release of hormones from endocrine glans
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What is one connection between the nervous and endocrine systems in the sympathetic nervous system?
sympa nervous system directly innervates the adrenal medulla to stimulate the release of epinephrine
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Hormone
signal of endo system molecule which is secreted into he bloodstream by endocrine gland and which has effects on distant target cells with the appropriate receptor
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Endocrine gland
ductless gland whose secretory products are picked up by capillaries supplying blood to the region
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Exocrine gland
secrete products into external environment by the way of ducts, which empty into the intestinal lumen or external world
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Hormone receptor
polypep that possesses a ligand-specific binding site binding of ligand ( hormone) causes the receptor to modify target cell activity tissue specificity of hormone action is determined by whether the cells of a tissue have the appropriate receptor
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Autocrine activity
when signalling molecules modify the activity of the cell that secreted them ex. T cells secrete interleukin 2, which binds to receptors on the same T cell to stimulate increased activity
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Hormone classes
2 classes Hydrophillic such as peptides and aa derivatives, bind to receptors on cell surface hydrophobic such as steroid hormones bind to receptors in the cellular surface
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Peptide hormones
synthesized in rough ER and modified in the Golgi stored in vesicles until they are needed and released by exocytosis dissolve in blood plasma in the blood stream because they are hydrophilic communicate with interior of target cell by the way of a second messenger cascade
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Mechanism of peptide hormone on receptor cell
peptide hormone first messenger which must bind to a cell surface receptor receptor is a polypeptide with a domain on the inner surface of the plasma membrane that contains the ability to catalytically activate a second messenger end result of second messenger activation is that the function of proteins in the cytoplasm is changed key feature of second messenger cascades is signal amplification, which allows a few activated receptors to change the activity of many enzymes in the cytoplasm
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overall effect of peptide hormones
modify activity of existing enzymes in the cytoplasm, effects are exerted rapidly, minutes to hours from time of secretion duration of effects is brief
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Two subgroups within the peptide hormone category
polypeptides and amino acid derivatives
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Polypeptide hormone examples
Insulin, complex tertiary structure with disulphide bridges secreted by beta cells of the pancreatic islets of Langerhans in response to elevated blood glucose and binds to cell surface receptor with cytoplasmic domain processing protein kinase activity
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Amino acid derivatives and example
derived from single amino acids and contain no peptide bonds ex. Tyr is parent molecule for catecholamines ( including epinephrine) and thyroid hormones
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Catcholamines
act like peptide hormones Epinephrine is an example small cyclic molecule secreted by adrenal medulla upon activation of the sympathetic nervous system binds to cell surface receptors to trigger a cascade of events that produces the second messenger cyclic AMP cAMP and activates protein kinases in the cytoplasm
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Thyroid hormones
act like steroid hormones incorporate I into their structure enter cells, bind to DNA and activate transcription of the genes involved in E mobilization
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Steroid hormones
hydrophobic molecules synthesized from cholesterol in smooth ER diffuse freely thru biological membranes not stored but diffuse into blood soon after they are made if not needed, then it is not made because of the hydrophobicity, they cannot be dissolved in the plasma
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what holds the steroid bound to a plasma protein?
no bond- just hydrophobic interactions
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mechanism of steroid hormones
small hydrophobic steroid hormone exerts its effects upon target cells by diffusing thru plasma membrane to bind with a receptor in the cytoplasm once it has bound its ligand, the steroid hormone-receptor complex is transported into nucleus, where it acts as a sequence-specific regulator of transcription because steroid hormones must modify transcription to change the amount and type of proteins in the cell, effects are exerted slowly , over a period of days and persist for days to weeks
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endocrine glands that secrete steroids and peptides
steroids regulating sexuality, reproduction and development are secreted by the testes , ovaries and placenta steroids regulating water balance and other processes are secreted by adrenal cortex all other endocrine glands secrete peptide hormones
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structure of peptides vs steroids
pep: hydrophilic , large ( polypeptides) or small ( aa derivs) st: hydrophobic, small
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site of synthesis for peptides vs steroids
pep: rough ER st: smooth ER
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Regulation of release for peptides vs steroids
pep: stored in vesicles until a signal for secretion is received st: synthesized only when needed and then used immediately, not stored
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transport in bloodstream for peptides vs. steroids
pep: free st: stuck to protein carrier
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specificity for peptides vs steroids
pep: only target cells have appropriate surface receptors (exception: thyroxine =cytoplasmic) st: only target cells have appropriate cytoplasmic receptors
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mechanism of effect for peptides vs steroids
pep: bind to receptors that generate second messengers which result in modification of enzyme activity st: bind to receptors that alter gene expression by regulating DNA transcription
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timing of effect for peptides vs. steroids
pep: rapid, short-lived st: slow, long-lasting
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Feedback regulation example with calcitonin
function of calcitonin is to prevent concentration of calcium in the serum from peaking above normal levels, and amount of calcitonin secreted is directly proportional to increase in concentration of calcium in serum above normal when concentration of calcium becomes elevated, calcitonin is secreted thus when concentration of calcium in serum levels fall, calcitonin secretion stops falling serum Ca level ( which is regulated) feeds back to the cells which secrete calcitonin ( regulators) the serum Ca level is a physiological endpoint which must be maintained at constant levels demonstrates the role of endocrine system in maintaining homeostasis
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homeostasis
physiological consistency
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tropic hormones
hormones that regulate hormones | meta regulators
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role of ACTH
stimulate increased activity of portion of adrenal gland called the cortex, which is responsible for secreting cortisol and other steroid hormones tropic hormone does not directly affect physiological endpoints regulates another regulator ( cortisol)
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cortisol
regulates physiological endpoints including cellular responses to stress and serum glucose
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feedback regulation for ACTH
level of ACTH is influenced by the cortisol | when cortisol is needed, ACTH is secreted, and when the serum cortisol increases sufficiently, ACTH secretion slows
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inhibitory secretion
negative feedback or feedback inhibition when the secretion of hormone inhibits further secretion most feedback in endo is negative
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Portion of brain which controls much of endocrine system
hypothalamus, located at the center of the brain
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hypothalamus role in endocrine system
controls endo by releasing tropic hormones that regulate other tropic hormones called releasing and inhibiting factors or hormones
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Ex of hypo regulation of endocrine system
hypo secretes corticotrophin releasing hormone ( CRH or CRF) F stands for factor role of CRH is to cause increased secretion of ACTH inhibited by cortisol like ACTH secretion
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damage to connection between hypo and pituitary
is fatal, unless daily hormonal replacement therapy is given
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hypothalamic-pituitary control axis
endocrine control center
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hypothalamus and pituitary
hypo controls pituitary by secreting hormones into bloodstream unique mini circulatory system is provided for efficient transport of hypothalamic releasing and inhibitory factors to the anterior pituitary
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hypothalamic pituitary portal system
hypothalamic hypophysial portal system | blood supply which links the hypothalamus to the pituitary gland
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pituitary gland
hypophysis | has 2 halves: front ( anterior) and back ( posterior)
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general rule for blood leaving the heart
moves through a capilliary bed before returning to the heart, since pressure drops substantially in capiliaries
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portal system blood flow
portal system consist of 2 capilliary beds in sequence, allowing for direct communication between near by structures
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2 portal systems you need to understand
hypothalamic pituitary portal | hepatic portal system ( from GI to liver)
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Anterior pituitary
adenohypophysis normal endocrine gland controlled by hypothalamic releasing and inhibiting factors ( essentially tropic hormones)
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posterior pituitary
neurohypophysis composed of axons which descend from the hypothalamus consist of neuroendocrine cells from the hypo
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neuroendocrine cells
neurons that secrete hormones into the bloodstream | hypothalamic neurons that send axons down to post.r pit.y are an examples
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hormones of posterior pituitary
ADH ( antidiuretic hormone or vasopressin) causes kidney to retain water during times of thirst oxytocin : causes milk let-down for nursing as well as uterine contractions during labor
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Are the hormones of the posterior pituitary created by the axon termini in the posterior pituitary or somas in the hypothalamus ?
All hypothalamic and pituitary hormones are peptides, no protein synthesis at axon termini. Therefore, ADH and oxytocin must be made in nerve cell bodies in the hypothalamus and transported down the axons to the posterior pituitary .
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Is epinephrine secreted by duct into the bloodstream?
No. Endocrine hormones are not secreted through ducts.
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Hormones which have broad effects on metabolism and energy usage
Thryoid hormone and cortisol
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Thyroid hormone
produced from Tyr in the thyroid gland and comes in 2 forms, with 3 or 4 I atoms per molecule production increased by thyroid stimulating hormone (TSH) by the anterior pituitary , which is regulated by the hypo and the CNS
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Mechanism of action of thyroid hormone
bind to a receptor in the cytoplasm of cells that regulates transcription in the nucleus effect of regulation: increase overall metabolic rate and body temperature and to stimulate growth in children exposure to cold increases the production of thyroid hormone
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Cortisol
Secreted in response to ACTH from the pituitary by the adrenal cortex
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Effects of cortisol
help body deal with stress helps to mobilize glycogen fat stores to provide energy during stress and increase consumption of proteins for energy effects are essential, removal of adrenal cortex can result in death of animals exposed to even a little stress
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Long term effects of cortisol
negative | including suppression of the immune system
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Would an inhibitor of protein synthesis block the action of thyroid hormone?
Yes. Thyroid hormone binds to a receptor that regulates transcription. The mRNA stimulated by thyroid hormone receptor in the nucleus must be processed and translated before effects of thyroid hormone can become evident.
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Would the production of ATP by mitochondria be stimulated or repressed by thyroid hormone?
Thyroid hormone stimulates basal metabolic rate throughout the body. More ATP is consumed so mito is stimulated to make more ATP
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Would thyroid hormone affect isolated mitochondria directly?
No Thyroid hor affects mito indirectly, thru regulation of nuclear genes
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``` releasing and inhibiting factors : class and gland which releases it ```
peptides | hypothalamus
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releasing and inhibiting factors: target effect
target: anterior pituitary effect: modify activity
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``` growth hormone: class and gland which releases it ```
peptides | anterior pituitary
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growth hormone: target effect
target: throughout the body, but primary one is the liver effect: increase bone and muscle growth, increase cell turnover rate
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``` prolactin: class and gland which releases it ```
peptide | anterior pituitary
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prolactin: target effect
target: mammary gland effect: milk production
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``` thyroid stimulating hormone : class and gland which releases it ```
tropic hormone peptide anterior pituitary
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TSH: target effect
target: thyroid effect: increase synthesis and release of TH
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``` adrenocorticotrophic releasing hormone (ACTH) : class and gland which releases it ```
peptide tropic hormone anterior pituitary
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ACTH: target effect
target: adrenal cortex effect: increase growth and secretory activity in adrenal cortex
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``` lutenizing hormone (LH) : class and gland which releases it ```
gonadotropic hormone peptide anterior pituitary
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LH: target effect
target: ovary, testes effect: ovulation, testosterone synthesis
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``` follicle stimulating hormone (FSH) : class and gland which releases it ```
gonadotropic hormone peptide anterior pituitary
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FSH: target effect
target: ovary, testes effect: follicle development, spermatogenesis
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``` antidiuretic hormone (ADH) : class and gland which releases it ```
aka vasopressin peptide posterior pituitary
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ADH: target effect
target: kidney | effect : water retention
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``` oxytocin : class and gland which releases it ```
posterior pituitary | peptide
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oxytocin: target effect
target: breast, uterus effect: milk letdown, contraction
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``` thyroid hormone : (TH) class and gland which releases it ```
aka thyroxine modified amino acid thyroid
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TH: target effect
child: necessary for physical and mental development adult: increase metabolic rate and temperature
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``` calcitonin: class and gland which releases it ```
thyroid C cells | peptide
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calcitonin: target effect
target: bone , kidney effect: lowers serum calcium ion concentration
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``` parathyroid hormone ( PTH): class and gland which releases it ```
parathyroids | peptide
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PTH: target effect
target: bone, kidney small intestine effect: raises serum calcium ion concentration
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``` thymosin: class and gland which releases it ```
found in children only peptide thymus
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thymosin: target effect
T cell development during childhood | target: white blood cells
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``` epinephrine : class and gland which releases it ```
modified amino acid | adrenal medulla
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epi : target effect
sympathetic stress response, rapid | target: muscles and blood vessels
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``` cortisol : class and gland which releases it ```
glucocorticoid steroid adrenal cortex
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cortisol: target effect
longer term stress response, increase in blood glucose concentration, increase protein catabolism, decrease inflammation and immunity target: liver, fat, muscles
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``` aldosterone : class and gland which releases it ```
mineralcorticoid steroid adrenal cortex
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aldosterone: target effect
target: kidney | increase sodium ion reabsorption to increase blood pressure
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``` sex steroids : class and gland which releases it ```
steroids | adrenal cortex
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sex steroids: target effect
not normally important, but an adrenal tumour can over produce these, leading masculinization or femininization
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``` insulin: class and gland which releases it ```
absent or ineffective in diabetes mellitus secreted by beta cells peptide endocrine pancreas ( islets of Langerhans)
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insulin: target effect
decrease blood glucose and increase glycogen and fat storage
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``` glucagon: class and gland which releases ```
alpha cells secrete peptide endocrine pancreas ( islets of Langerhans)
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glucagon: target effect
increase blood glucose and decrease glycogen and fat storage
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``` somatostatin: class and gland which releases ```
``` peptide delta cells secrete endocrine pancreas ( islets of Langerhans) ```
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somatostatin: target effect
inhibits many digestive processes
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``` testosterone: class and gland which releases ```
steroid | testes
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testosterone: target effect
male characteristics, spermatogenesis
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``` estrogen: class and gland which releases ```
steroid | ovaries or placenta
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estrogen: target effect
female characteristics, endometrial growth | target: female reproductive system
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``` progesterone: class and gland which releases ```
steroid, | ovaries or placenta
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progesterone: target effect
endometrial secretion, pregnancy | target: mammary glands, uterus
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``` atrial natriuretic factor (ANF) class and gland which releases ```
peptide | heart secretes this
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ANF: target effect
target: kidney | increase urination to decrease blood pressure
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``` erythropoietin class and gland which releases ```
peptide | kidney
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erythropoietin: target effect
target: bone marrow | increase RBC synthesis
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SC: | specific functions
Specific: controls simple stretch and tendon reflexes | controls primitive processes such as walking, urination and sex organ function
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Medulla: | specific functions
Specific: - controls autonomic processes such as blood pressure, blood flow , heart rate, respiratory rate, swallowing and vomiting - controls reflex reactions such as coughing and sneezing - relays sensory info to the cerebellum and thalamus - rhythymicity centers found here
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Pons: specific functions
Specific: - controls antigravity posture and balance - connects spinal chord and medulla with upper regions of brain - relays info to cerebellum and thalamus - receives info from vestibular apparatus in the inner ear, which monitors acceleration and position relative to gravity
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Cerebellum: specific functions
Specific: - Integrating center for complex movements - coordination of complex movement, balance and posture , muscle tone, spatial equilibrium - receives info from vestibular apparatus in the inner ear, which monitors acceleration and position relative to gravity
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Midbrain: specific functions
Specific: - integration of visual and auditory info - visual and auditory reflexes - wakefulness and consciousness - coordinates info on posture and muscle tone - contains much of reticular activating system (RAS) , which is responsible for arousal or wakefulness.
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Thalamus: specific functions
Specific: - relay and processing centers for somatic ( conscious) sensation - relay info between the spinal cord and cerebral cortex
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Hypo: specific functions
Specific: - controls homeostatic functions ( such as temp regulation, fluid balance, appetite) through both neural and hormonal regulation - controls primitive emotions such as anger, rage , sex drive - controls pituitary gland - contains centers for controlling emotions and autonomic functions, has a major role in hormone system especially since it has a primary link between nervous and endocrine systems and by controlling pituitary gland, is fundamental control center for endocrine system
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Basal nuclei: specific functions
Specific: - regulate body mvmt and muscle tone - coordination of learned mvmt patterns - general pattern of rhythm mvmts ( such as controlling the cycle of arm and leg movements during walking) - subconscious adjustments of conscious mvmts - voluntary motor control
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Limbic system: specific functions
Specific: - controls emotional states - links conscious and unconscious portions of the brain - helps with memory storage and retrieval
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Cerebral cortex: Specific functions
Specific: - divided into 4 lobes ( parietal, temporal, occipital , frontal) with specialized subfunctions - conscious though processes and planning, awareness and sensation - perception and processing of special senses ( vision, hearing, smell, taste, touch) - intellectual function ( intelligence, learning, reading, communication) - abstract thought and reasoning - memory storage and retrieval - initiation and coordination of voluntary mvmt - complex motor patterns - language ( speech production and understanding) - personality