Neuro/Endo Systems Flashcards
(82 cards)
0
Q
Communication System that detects, processes, and responses to stimuli
A
Nervous System
1
Q
Evolutionary concentration of interneurons at anterior end of organism
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Cephalization
2
Q
Type of excitable cell that detects and processes stimuli
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Neuron
3
Q
Structural and metabolic support for neurons
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Neuroglia
4
Q
What are the three types of neurons and their functions
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- Sensory: detect stimuli (receptors)
- Interneurons: integrate signals (integrators)
- Motor: signal effectors to perform actions
5
Q
Two Types of Nervous Systems and function
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- Central: Processes and responses to signals
2. Detects and relays signals, responses
6
Q
Main Nerves in Body and number
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Cranial (12 pairs) Cervical (8 pairs) Thoracic (12 pairs) Lumbar (5 pairs) Sacral (5 pairs) Coccygeal (1 pair)
Ulnar (1/arm)
Sciatic (1/leg)
7
Q
Axons relaying signals into CNS
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Afferent
8
Q
Axons relaying commands from CNS
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Efferent
9
Q
Neuron extensions that receive signals
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Dendrites
10
Q
Neuron extension that sends signal
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Axon
11
Q
Zones of a neuron
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Input zone (cell body and dendrites) Trigger zone (special membrane section) Conducting zone (axon) Output zone (axon ending/synapse)
12
Q
Term for Electric Gradient across neuron not receiving a signal
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Resting Membrane Potential ~= -70 mV
13
Q
Stimulation of excitable cell
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Action Potential
14
Q
An Action Potential is…
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an abrupt reversal of the electric gradient across a neuron
15
Q
Neurons maintain resting potential by…
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- actively pumping Sodium out of cell and Potassium into cell
- more potassium, less sodium in cell
-sodium not able to leak back into cell
16
Q
Action Potential triggers voltage reversal by…
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Openings voltage-activated sodium and potassium gates
17
Q
Steps of an action potential:
A
- Pressure, other stimulus on sensory neuron deforms membrane, allows ions through. Creates graded potential
- If potential is above threshold level, gated ion channels open, bringing in sodium ions.
- Increasing positive charge of cell leads to more gates opening (positive feedback mechanisms)
- Action Potential self-propagates along conducting zone (axon)
18
Q
What is the Threshold Level?
A
Voltage needed to activate gated ion channels in trigger zone
19
Q
Why is an AP an all-or-nothing event?
A
Because once the threshold level has been reached, stimulus strength has no bearing on proceeding AP, same number of gates will open due to positive feedback.
20
Q
Why does an AP flow only one way?
A
Because after a timeout period, ion gates close and are deactivated for awhile, causing ions to only be able to flow to a new part of the conducting zone.
21
Q
Point of interaction between two neurons (signal transfer location)
A
Chemical Synapse
22
Q
Cell sending a signal across a synapse
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Presynaptic cell
23
Q
Cell receiving a signal across a synapse
A
Postsynaptic cell
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Gap between pre- and postsynaptic cells
Synaptic Cleft
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Signalling molecule that relays message between neurosystem cells
Neurotransmitter
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Sum of all signals entering an interneurons
Synaptic Integration
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Neurotransmitter that induces muscle contractions in smooth muscle, slows cardiac contraction, has roles in mood and memory
Acetylcholine (ACh)
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Neurotransmitter that speeds heart rate, dilutes pupils and airway, slows gut contractions, increases anxiety
Epinephrine, norepinephrine
Aka Adrenaline
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Neurotransmitter that dampens other neurotransmitters, has roles in memory, learning, fine motor control
Dopamine
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Neurotransmitter that elevates mood, has role in memory
Serotonin
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Neurotransmitter that inhibits release of other neurotransmitters
GABA
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A molecule that influences effects of neurotransmitters
Neuromuscular or
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3 ways of removing neurotransmitters from synaptic cleft
1. Diffusion back into presynaptic cell/extra cellular fluid
2. Pumping back into presynaptic cell or neuroglia
3. Breakdown by released enzymes
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How does nerve gas work?
Inhibits removal of neurotransmitters from synaptic cleft, negatively impacts ability of cells to signal
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Types of Interneuron Circuits
1. Diverging: dendrites extend from one block of neurons and axons extend to another
2. Converging: many neurons converge their signals on a small number of neurons
3. Reverberating: neuron loops signal back on itself
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What surrounds axons and what are their purpose?
A myelin sheath made of Schwann cells. It prevents ions from crossing the cell membrane at any point but nodes, which lay between two cells. The nodes are unsheathed but have many Na gates that speed up A.P.s immensely. Allowing rapid signal movement.
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Reflex
Autonomic response to a stimulus that does not require any thought
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Steps of the stretch reflex
1. Force applied to muscle, AP triggered through sensory neurons on deformed muscle spindle
2. AP travels to spinal cord
3. Neurotransmitter released at spinal cord, stimulates motor neuron
4. Motor neuron releases ACh, stimulates muscle fibres
5. Muscle contracts
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The two classes of nerves in PNS and roles
1. Somatic: information to/from skin, tendons, skeletal muscle; responsible for voluntary motion
2. Autonomic: information to/from viscera; involuntary actions
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2 divisions of autonomic nerves and roles
1. Sympathetic: active during stress; fight or flight reflexes
2. Parasympathetic: active during relaxation; daily housekeeping, digestion, urine formation
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Two types of CNS matter
Grey matter - inner matter: cell bodies, dendrites, unsheathed axons, neuroglia
White matter - outer matter: myelin-sheathed axons, neuroglia
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Spinal roots for different neuron types
Dorsal root - sensory/afferent neurons
Ventral root - motor/efferent neurons
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Brain can be divided into...
1. Cerebrum (higher-order thought, motion)
2. Cerebellum (balance)
3. Brain Stem (basic life functions)
OR
1. Forebrain
2. Midbrain
3. Hindbrain
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Functions of the medulla oblongata
Respiration, circulation, swallowing, coughing, affects sleep
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Functions of the Cerebellum
Receives input from muscle spindles, eyes, ears, forebrain regions; controls balance and posture
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Functions of the Pons
Controls respiration, connects different parts of brain, controls signal flow
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Function of the cerebrum
Processes sensory input, controls muscles, functions in memories, emotion and higher thought
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Function of the thalamus
Sorting and relay station, role in memory
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Function of the corpus callosum
Connects and coordinates the two brain hemispheres
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Clear fluid that cushions brain and spinal cord
Cerebrospinal fluid
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Function of the blood-brain barrier
Protects brain from harmful substances, carefully controls homeostasis in the brain by very selectively allowing substances into cerebrospinal fluid.
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The lobes of the cerebral cortex
Frontal, parietal, occipital, temporal
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Primary Motor Cortex
In frontal lobe, controls and coordinates movements of skeletal muscle
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Premotor cortex
In frontal loge, ahead of primary motor cortex
| Regulates complex movements and learned motor skills; coordinates actively of multiple muscle groups
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Broca's Area
In frontal lobe
| Translates thought to speech, controls tongue, throat, lips for speech
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Primary Somatosensory Cortex
Located at front of parietal lobe
| Receiving centre for sensory input form skin and joints, part of it deals with taste perception
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Primary visual cortex
Back of occipital lobe
| Receives input from eyes
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Prefrontal Cortex
Front of frontal lobe
| Personality, abstract thought, judgement, planning, empathy
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The limbic system...
Governs emotions, assists in memory, correlates organ activity with self-gratifying behaviour
Encircles upper brain stem
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The functions of the hypothalamus (limbic)
Controls homeostasis
| Correlates emotions and visceral activity
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Functions of the hippocampus
Helps store and access memories
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Functions of the amygdala
Interprets social clues, role in sense of self
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Functions of the Cingulate Gyrus
Helps regulate emotions and pain
| Involved in predicting and avoiding negative consequences
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neuroglia functions
```
Structure, paths
Insulation (Schwann cells)
Immune defence
Maintaining proper ion concentrations
Synthesize various substances (growth factor, lactate)
Consume dead cells
```
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Types of signalling molecules
1. Hormones - long-distance body communication
2. Neurotransmitters - secreted by neurons into synaptic cleft
3. Local signalling molecules - secreted by cells, affect only nearby tissue
4. Pheromones - air/water dissolved substances that help integrate social behaviour
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Main glands of the endocrine system
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Hypothalamus
Pituitary
Pineal
Thyroid
Parathyroid
Thymus
Adrenal
Pancreas
Gonads (ovaries/testes)
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Cell sensitivity to hormones is affected by...
```
Presence of proper receptors
Interaction between hormones
Concentration of hormone in tissue
Cell's nutritional and metabolic state
Environment conditions
```
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Hypothalamus (endocrine)
Secretes releasing hormones:
Oxytocin (contractions, lactation, social behaviour)
Antidiuretic hormone (controls amount of H2O lost in urine)
Sends hormones to posterior pituitary gland.
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Pituitary Gland
Two lobes: anterior and posterior
Controlled by releasing/inhibiting hormones from hypothalamus
Secretes:
andrenocorticotropic hormone: stimulates release of cortisol
Thyroid-stimulating hormone: stimulates release of thyroid hormone
Growth hormone (somatotropin): promotes bone, tissue growth
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Skin-covered cartilage flap of outer ear
Pinna
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Bones of the middle ear
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
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Snail-like structure of inner ear
The cochlea
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The two ducts of the inner ear
Scala vestibuli
| Scalia tympani
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Structure of scala media (middle cochlear duct)
Basilar membrane which differentially vibrates
| Organ of Corti that has hair cells that stick into the tectorial membrane
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Covers the front of the eye
Cornea
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Covers the back of eye
Sclera
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Provides nutrition for eye and absorbs missed light
Choroid
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Muscles that adjust lens shape
Ciliary muscles
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Eye structure with photoreceptors
Retina
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Lubricates lens and outer eye
Aqueous humour
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Fills eyeball and gives structure
Vitreous body
