Units 21-24: The Nervous System and Sensory Reception Flashcards
1
Q
Homeostasis
A
State of relative stability within the body.
2
Q
Peripheral Nervous System
A
Nerves that carry sensory information to the CNS and from the CNS to the extremities.
Divided into the somatic system and the autonomic system.
3
Q
Neurons
A
Basic structural and functional units of the nervous system.
Respond to chemical and physical stimuli to conduct electrochemical signals.
4
Q
Glial Cells
A
Are the framework for the nervous tissues.
Nourish, protect, and remove waste from neurons.
10:1 ratio to number of neurons.
5
Q
Nerves
A
Neurons are organized into tissues called nerves.
Surrounded by protective connective tissues.
6
Q
Reflex Arcs
A
Simple connections of neurons that explain reflexive behaviors (involuntary reaction to danger before a conscious reaction).
- Sensory receptor
- Sensory neuron
- Association/Interneuron
- Motor Neuron
- Effector
7
Q
Dendrites
A
Short, branching terminals that receive nerve impulses from other neurons or sensory receptors, and relay the impulse to the cell body.
Branching increases surface area available to receive information.
8
Q
Cell Body
A
Of a neuron. Contains the nucleus and is the site of the cell’s metabolic reactions.
Processes input from the dendrites, relays input to the axon.
Are the signals more inhibitory or excitatory?
9
Q
Axon
A
Conducts impulses away from the cell body. Terminal end of axon branches into fibres.
Releases chemical signals into the space between it and neighboring cells.
10
Q
Myelin Sheath
A
A fatty layer around the axon.
Protects the axon and speeds the rate of nerve impulse transmission.
Made of Schwann cells.
11
Q
Schwann Cells
A
A type of glial cell.
Form myelin by wrapping themselves around the axon.
12
Q
Membrane Potential
A
The charge separation across the membrane is a form of potential energy.
13
Q
Resting Membrane Potential
A
The potential difference across the membrane in a resting neuron.
-70mV in most neurons.
14
Q
Polarization
A
The process of generating a resting membrane potential of -70mV.
Is achieved by charged protein molecules in the intracellular fluid which are too big to fit through the cell membrane. Also, cell membrane is impermeable to smaller negatively charged ions; chloride.
15
Q
Sodium-potassium Exchange Pump
A
System uses ATP to transport 3 sodium ions out of the cell and 2 potassium ions into the cell.
Contributor to polarization.
16
Q
Depolarization
A
A neural membrane is depolarized if the transmembrane potential is reduced to less than the resting potential of -70mV.
When the voltage gaged sodium channels open, causing sodium to leave the cell rapidly.
17
Q
Nodes of Ranvier
A
Where action potentials occur in myelinated neurons.
18
Q
Action Potential
A
The change in charge that occurs when the gates of the K+ channels close and the gates of the Na+ channels open after a wave of depolarization is triggered.
- Sodium rushes into cell. (Depolarization triggered by voltage change)
- Potassium rushes out of the cell. (Repolarization triggered by diffusion and the rush of sodium)
- Switch. Return to normal through potassium pump. Causes refractory period.
19
Q
Threshold Potential
A
The potential difference of -55mV.
Is what makes the action potential an all or none event.
20
Q
Repolarization
A
The movement of potassium ions out of the cell once the region of the axon hits +35mV.
This reinstates the negative charge, overshooting to -90mV, allowing all processes to return to normal.
21
Q
Refractory Period
A
The time after an action potential, where the membrane cannot be stimulated to undergo another action potential.
Prevents impulses from going backwards.
22
Q
Synapse
A
The connection between two neurons, or a neuron and an effector.
23
Q
Neuromuscular Junction
A
A synapse between a motor neuron and a muscle cell.
24
Q
Neurotransmitters
A
Chemical messengers carry neural signal from one neuron to another, or an effector.
Have either excitatory or inhibitory effects.
25
Acetylcholine
A neurotransmitter that crosses a neuromuscular junction.
| Excites muscle cell membrane, causing depolarization and contraction of the muscle fibre.
26
Cholinesterase
An enzyme that breaks down acetylcholine. Allows ion channels to close and membranes to repolarize.
27
Somatic System
Part of the peripheral nervous system that carries sensory information to the CNS and instructions from the CNS to the skeletal muscles.
Voluntary.
Includes neurons in the: head, trunk, and limbs.
12 pairs of cranial nerves; 31 pairs of spinal nerves.
28
Autonomic System
Stimulate or inhibit glandular secretions and functioning of the smooth and cardiac muscles.
Involuntary.
Controlled by the hypothalamus and medulla oblongata.
Divided into two: sympathetic and parasympathetic nervous systems.
29
Inhibitory Effects
Receptor proteins trigger potassium channels to open. Allowing potassium ions to flow out; more negative transmembrane potential; hyperpolarization.
Prevents an action potential.
30
Situations That Increase The Amount of Neurotransmitter In The Synapse
1. A chemical is given that mimics the effects of the neurotransmitter.
2. A chemical is given that prevents the re-uptake of the neurotransmitter.
3. A chemical is given that interferes with the enzyme that breaks down the neurotransmitter.
31
Situations That Decrease The Amount Of Neurotransmitter In The Synapse
1. A chemical that blocks the receptors for the neurotransmitter is added.
2. A chemical that breaks down the neurotransmitter or
3. Enhances the activity of the re-uptake of the neurotransmitter.
32
Grey Matter
Is grey because it contains mostly cell bodies, dendrites, and short, unmyelinated axon.
Outside area of the brain, and the H-shaped core of the spinal cord.
33
White Matter
Contains myelinated axons that run together in tracts.
| Forms the inner region of some areas of the brain, the outer area of the spinal cord!
34
Cerebellum
Walnut shaped structure located below and behind the cerebrum.
Unconscious coordination of posture, reflexes, and body movements.
Voluntary motor skills.
Receives information from proprioceptors, found in skeletal muscles and joints.
35
Medulla Oblongata
Base of the brainstem, connects to the spinal cord.
| Control automatic, involuntary responses including heart rate, blood pressure, breathing, swallowing, and coughing.
36
Midbrain
Found above the pons and brainstem. Relays visual and auditory information between areas of the hindbrain and forebrain.
Important role in eye movement and control of skeletal muscles.
37
Spinal Cord
Communication link between the brain and the peripheral nervous system.
Tissues protected by cerebrospinal fluid, soft tissues, and the spinal column.
38
Brain
Divided into three regions, the hindbrain, the midbrain, and the forebrain.
Protected by the skull and meninges.
39
Hindbrain
Includes:
- cerebellum
- medulla oblongata
- pons
40
Meninges
Three layers of tough elastic tissue within the skull and spinal cord.
Prevent the direct circulation of blood through the cells of the brains.
41
Pons
Above and in front of the medulla oblongata.
Relay center between the neurons of the right and left halves of the cerebrum, the cerebellum, and the rest of the brain.
42
Thalamus
Base of the forebrain.
Relays and connects information to the different parts of the brain.
Between the hindbrain, and the front brain, and the sensory system except smell.
43
Hypothalamus
Below the thalamus.
Regulates the homeostasis through blood pressure, heart rate, body temperature.
Regulates emotions and certain aspects of behavior.
Links between the nervous system and the endocrine system. Produces and releases hormones that regulate the pituitary gland.
44
Cerebrum
The big part of the brain. Divided into left and right.
45
Blood-brain Barrier
The separation of the blood and CNS.
| Supplies the brain with nutrients and oxygen,
46
Forebrain
Includes:
- Thalamus
- Hypothalamus
- Cerebrum
47
Blood-brain Barrier
The separation of the blood and CNS.
Supplies the brain with nutrients and oxygen by transport mechanisms.
Capillaries are made of tightly fused epithelial cells, are only permeable to selective; lipid-soluble substances.
48
Cerebrospinal Fluid
Circulates through the space within the brain and spinal cord.
Transports hormones, white blood cells, and nutrients across the blood-brain barrier.
Circulates between layers of the meninges, and acts as a shock absorber
49
Cerebral Cortex
The layer of outer grey matter covering the inner layer of white matter of the cerebrum.
Language, memory, personality, vision, conscious thought. Activities associated with thinking and feeling.
Convoluted to increase surface area.
50
Cerebral Cortex
The layer of outer grey matter covering the inner layer of white matter of the cerebrum.
Language, memory, personality, vision, conscious thought. Activities associated with thinking and feeling.
Convoluted to increase surface area.
Divided into four lobes.
51
Forebrain
Includes:
- Thalamus
- Hypothalamus
- Cerebrum
52
Occipital Lobes
Receive and analyze visual information.
| Recognizing and seeing objects.
53
Temporal Lobes
Share processing visual information, auditory reception. Understanding speech, retrieving visual and verbal memories.
Contains Wernicke's area.
54
Parietal Lobes
Primary somatosensory and somatosensory association area. Taste area as well.
Touch, position and orientation of the body.
55
Frontal Lobes
Integrate information from other parts of the brain.
Critical thinking, memory, and personality.
Contains Broca's area.
Various complex motor functions as well.
56
Broca's Area
Speech.
Coordinates muscles for speaking and translates thought into speech.
If this part got affected, you couldn't say words, but you could understand.
57
Wernicke's Area
Language comprehension.
| If this part got affected, you could say words but they don't make sense.
58
Left Brain
Segmental, logical ways of thinking, linguistic and mathematical skills.
59
Sympathetic Nervous System
Activated in stressful situations. Fight or flight response.
Release norepinephrine.
Triggers adrenal glands to release epinephrine and norepinephrine.
Blood pressure, heart rate, breathing rate increase.
Inhibits certain areas of the body, i.e. digestion.
60
Norepinephrine
A neurotransmitter that has an excitatory effect on its target muscles.
61
Parasympathetic Nervous System
Activated when the body is at rest. Rest and digest.
| Slows heart rate, reduces blood pressure, promotes digestion, stimulates reproductive organs.
62
Sensory Receptors
Nerve endings and cells that detect sensory information.
| Photoreceptors, chemoreceptors, mechanoreceptors, and thermoreceptors.
63
Sensation
Occurs when the neural impulses arrive at the cerebral cortex.
64
Perception
How the cerebral cortex interprets the meaning of the sensory information.
65
Sensory Adaptation
The filtering by the brain of redundant, insignificant sensory information.
66
Photoreceptors
Receive visual information.
Stimulus: Light
Rods and cones.
67
Chemoreceptors
Stimulated by certain chemicals and internal environment stuff.
Taste, smell, internal sense.
68
Mechanoreceptors
Mechanical forces by some kind of pressure.
| Touch/pressure/pain/hearing/balance/body position.
69
Thermoreceptors
Detect heat and cold in the skin.
70
Sclera
The white, tough, and fibrous protective outer layer of the human eye.
71
Cornea
The transparent part of the sclera.
72
Choroid
The intermediate layer of the eye.
Absorbs stray light rays that are not detected by photoreceptors.
Contains blood cells that nourish the eye.
73
Iris
The doughnut-shaped, colored muscle formed from the choroid at the front of the eye; adjusts the central dark pupil to regulate the amount of light that enters the eye.
74
Pupil
Opening for the light to enter the inner eye.
75
Adaptation
The process in which the iris adjusts the size of the pupil based on light conditions.
76
Retina
Internal layer of the eye. Thin layer that contains rods and cones.
77
Rods
Sensitive to light intensity (brightness). Located in the retna.
Detect motion and are responsible for peripheral vision.
78
Cones
Sensitive to different colors. Located in the back of the fovea centralis.
Requires intense light to be stimulated.
High-acuity tasks, i.e. reading.
3 types of cones, red, blue, and green.
79
Optic Nerve
The rods and cones send sensory impulses to the brain via the optic nerve.
80
Aqueous Humour
The watery fluid that fills the anterior chamber of the eye.
Maintains the shape of the cornea and provides oxygen and nutrients for surrounding cells.
81
Glaucoma
Condition caused when ducts that drain the aqueous humor in the eye are blocked; resulting pressure ruptures delicate blood vessels in the eye and causes deterioration of the cells due to a lack of oxygen and nutrients. Can lead to blindness if left untreated.
82
Vitreous Humour
Jelly like fluid which fills the posterior chamber of the eye.
83
Lens
Heald in place by the ciliary muscles and suspensory ligaments.
84
Accommodation
The reflex ability of the lens to change shape in order to focus images clearly on the retina.
85
Cataracts
A condition in which the proteins structure of the lens starts to degenerate, making it opaque and preventing light from passing through. Results in grey-white spots.
86
Astigmatism
a condition due to an uneven curvature of part of the cornea. Results in blurred vision.
87
Myopia
A condition in which a person can see things close up, but not 20/20.
Concave lenses can fix this.
88
Hyperopia
Can see clearly from 20 fee, but cannot focus on nearby objects because the eyeball is too short.
Convex lenses can fix this
89
Fovea Centralis
Contains a high density of cones, and provides acute vision.
90
Color Blindness
Color deficiency, caused by lack or deficiency in particular cones, usually red and green cones.
91
Blind Spot
Where the ganglion cells merge to form the optic nerve. Does not contain any photoreceptors; cannot detect light.
92
Retinal Detachment
A condition in which the retina becomes separated from the choroid vessels that supply it with oxygen due to a change in consistency of the vitreous fluid.
Can be corrected if detected early enough.
Many causes: inflammatory disorder, advanced diabetes, injury or trauma.
93
Macular Degeneration
A condition in which the cones are destroyed due to the thickened choroid vessels. Blurring or blind spot in central vision.
Caused by a condition, smoking, obesity, sunlight can implicate the condition.
94
Sound Waves
Small fluctuation in air pressure resulting from sound, which causes particles around the source to vibrate and move.
These movements are detected as sound.
95
Outer Ear
Consists of the pinna and auditory canal.
96
Pinna
The outside flap of the ear made of skin and cartilage, shaped to enhance sound vibrations and focus them into the ear.
97
Auditory Canal
A 2.5cm long tube that leads to the eardrum.
Amplifies sound waves.
Lined by hair and earwax which prevent foreign materials from seeping into the ear.
98
Middle Ear
Air filled space that is bordered on one side by the tympanum.
99
Tympanum
The eardrum.
Round elastic structure that vibrates in response to sound waves.
Vibrations are amplified and passed on to ossicles.
100
Ossicles
Three tiny, interconnected bones in the middles ear.
Amplify the strength of the vibration.
Malleus > incus > stapes
Stapes concentrates the vibration into the oval window.
101
Oval Window
Membrane-covered opening in the wall of the inner ear.
102
Eustachian Tube
Connects the middle ear to the throat.
| Allows to equalize air pressure when a change happens around the ear.
103
Inner Ear
Consists of The Semicircular canals, the vestibule, and the cochlea.
104
Cochlea
Used for hearing.
| Mechanical energy of sound is converted into electrochemical impulses.
105
Organ of Corti
Found in the middle chamber of the cochlea.
| Organ of hearing. Along the base is the basilar membrane.
106
Basilar Membrane
Part of the organ of Corti where sensory mechanoreceptors; hair cells are attached.
107
Hair Cells
Thin projections called stereocilia stick out of the top of cells; which are embedded with tectorial membrane.
108
Tectorial Membrane
One of two parallel membranes that comprise of the organ of Corti and in the inner ear(the other being the basilar membrane); during the transmission of sound waves, the basilar membrane vibrates causing the sensory hairs to flex against the tectorial membrane.
109
Semicircular Canals
One of the three components of the inner ear; consists of three fluid filled loops, arranged in three different planes contain mechanoreceptors that detect hard and body rotation.
110
Rotational Equilibrium
Head rotation.
111
Gravitational Equilibrium
The balance required while moving the head forward and backward.
112
Utricle
Saclike cavity in the vestibule of the inner ear; contains sensory receptors for gravitational equilibrium.
113
Saccule
Saclike cavity in the vestibule of the inner ear; contains sensory receptors for gravitational equilibrium.
114
Otoliths
Calcium carbonate granule associated with sensory receptors for detecting movement of the head; in vertebrate, located in the utricle and saccule in the vestibule of the inner ear.
115
Proprioceptors
Type of mechanoreceptor found in muscles, tendons, and joints; senses the body's position and movements to send information about body position to the brain.
116
Taste Buds
Sensory receptors in the bumps (papillae) of the tongue.
117
Olfactory Cells
Chemoreceptor for the sense of smell; lines the upper nasal cavity.
118
Olfactory Bulb
Region of the forebrain where ends of sensory nerve fibers from nose terminate and transmit olfactory information to other areas of the brain.
119
MRI Scan
A noninvasive brain mapping technology that uses magnetic fields.
Magnetic Resonance Imaging
120
PET Scan
A noninvasive brain mapping technology that uses radioactive substances.
