BIO 360 - Exam 2 - Chapter 8 Nervous System SP 2023 PowerPoint Flashcards
sliding filament mechanism
Andrew Huxley and Hugh Huxley (no relation!)
2004 Nobel Prize in Physiology or Medicine -
Olfactory sensory cells that express the same receptor
project to the same area (glomerulus) in the olfactory bulb.
Linda Buck, Fred Hutchinson, Richard Axel
Reduced silver staining technique
(July 7, 1843 – January 21, 1926)
Nobel Prize in Physiology or Medicine in 1906
Camillo Golgi
Neuron Doctrine
(May 1, 1852 – October 17, 1934)
Nobel Prize in Physiology or Medicine in 1906
Santiago Ramón y Cajal
The Brain: Phineas Gage (1823 – May 21, 1860)
* Association of frontal lobes and personality
Signaling in neurons
Basis of the Action Potential
Nobel Prize in Physiology or Medicine in 1963
Sir Alan Hodgkin, Sir Andrew Huxley
Signaling in neurons
Graded local potential
Nobel Prize in Physiology or Medicine in 1963
Sir John C. Eccles
Synaptic Transmission
Chemical - synapse & Electrical - gap junction
Nobel Prize in Physiology or Medicine in 1970
Julius Axelrod, Ulf S. von Euler & Sir Bernard Katz
What five things constitute the Neuron Doctrine?
- CELLS ARE DISCRETE UNITS
- PRINCIPLE OF DYNAMIC POLARIZATION
Information flows in one direction
Input->Integration->Output - PRINCIPLE OF CONNECTIONAL SPECIFICITY
Connections determine function
Fig. 8.1 ESSENTIALS The Organization of the Nervous System
What are the three specializations of the cerebral cortex?
(1) Sensory areas (Input): Sensory input translated into
perception
(2) Association areas (Integration): Integrate information
from sensory and motor areas. Can direct voluntary
behaviors.
(3) Motor areas (Output) Direct skeletal muscle or glandular movement.
General layout of the nervous system
Diagrams showing: frontal lobe, central sulcus, parietal lobe, occipital lobe, temporal lobe, and lateral (Syvian) fissure.
Frontal lobe (prefrontal association area): coordinates information from other association areas and controls some behaviors.
Temporal lobe (auditory association area and auditory cortex): hearing.
Occipital lobe (visual association area and visual cortex): Vision
Parietal lobe (sensory association area and primary somatic sensory cortex): information from the skin, musculo-skeletal system, viscera and taste buds.
Diagram showing: cerebrum, diencephalon, midbrain, pons, cerebellum, medulla, spinal cord, cervical enlargement, lumbosacral enlargement, Cauda equina.
Spinal Cord – External and Internal Anatomy
Which part is the white matter and which part is the grey matter.
Cerivical, Thoracic, Lumbar, Sacral areas.
White matter is tissue in the brain composed of nerve fibers. The fibers (called axons) connect nerve cells and are covered by myelin (a type of fat). The myelin is what gives white matter its white color.
Grey matter contains most of the brain’s neuronal cell bodies. The grey matter includes regions of the brain involved in muscle control, and sensory perception such as seeing and
hearing, memory, emotions, speech, decision making, and self-control.
Autonomic Nervous System
What is the difference between parasympathetic and sympathetic?
Parasympathetic
* Cranio-sacral “rest and digest” (output).
- Second stage neurons are near the target organ.
- Cholinergic then cholinergic.
Sympathetic
* Thoraco-lumbar “fight or flight” (output).
- Second stage neurons are far from the target organ.
- Cholinergic then noradrenergic.
Cell type 1: Neurons
- Neurons have ______ and ______ signaling properties.
- ______ ______ divide mitotically in adult.
What are the input, integration, & output?
- Neurons have ACTIVE and PASSIVE signaling properties
- DO NOT divide mitotically in adult
Input: Dendrites receive chemical information from presynaptic neuron.
Integration: Axon hillock
Output: Axons carry signal electrically over distance. Chemicals released from presynaptic bulb into synapse.
Neurons - classification
What are the three different classes based on FUNCTION?
- SENSORY - translate physical stimulus into electrical signals
- INTERNEURON - processing
- MOTOR NEURON - activate muscles and other target organs
(e.g. glands)
What is the difference between bipolar, anaxonic, and multi-polar neurons?
(sensory) Bipolar neurons have two relatively equal fibers extending off the central cell body.
(interneuron) Anaxonic CNS interneurons have no apparent axon.
(interneuron) Multi-polar CNS interneurons are highly branched but lack long extensions.
(efferent) A typical multipolar efferent neuron has 5-7 dendrites, each branching four to six times. A single long axon may branch several times and end at enlarged axon terminals.
Cells of Nervous System (NS): Axonal Transport
- Slow axonal transport
Moves material by axoplasmic flow at 0.2–2.5 mm/day - Fast axonal transport
Moves organelles at rates of up to 400 mm/day
Forward transport: from cell body to axon terminal
Backward transport: from axon terminal to cell body - Vesicles and organelles are moved by the cytoskeletal system
- Two proteins (dynein & kinesin)
Requires ATP!
Fig. 8.3 Fast axonal transport
How does the axonal transport move proteins and organelles between cell body and axon terminal?
(1) peptides synthesized and packaged
(2) Fast axonal transport along microtubule network
(3) vesicle contents released by exocytosis
(4) synaptic vesicles recycling
(5) Retrograde fast axonal transport
(6) oldest membrane components digested in lysosomes
What are the 5 functions of Glial cells?
(2) BUFFER extracellular space and maintain concentrations of ions - Remove NT’s
(3) GUIDE DEVELOPING neurites - so they make the right
connections!
(4) give rise to MYELIN
(5) SCAVENGERS: Debris/waste and transmitter removal.
(1) SUPPORT ELEMENTS: Lend firmness and structure to
brain
______ form ______ ______.
Oligodendrocytes / myelin sheaths
Fig. 8.5(c) ESSENTIALS Glial cells
Locate the cell body, nodes of ranvier, schwann cell nucleus, myelin and axon.
Blood brain barrier is formed by ______ cells. The blood–brain barrier protects the brain from chemicals in the blood and maintains the ionic environment crucial for signaling.
glial
Electrical Signals: Nernst Equation
Membrane potential is influenced by what three things?
- Concentration gradient of ions
- Valence (z)
- Membrane permeability (P) to those ions
Electrical Signals: GHK Equation
What does the GHK Equation predict?
Predicts membrane potential using multiple ions
Vm is E - electrical (equilibrium) potential
Electrical Signals: GHK Equation
___»_space;> ___ at rest
* So ___ ______ and the resting potential is closest to the ______
Nernst potential
Ex., PNa/ PK > 1/1000; e.g. permeability to ___ is 1,000 fold higher
* But still not quite accurate! What’s the problem?
The sodium-potassium pump stabilizes the RMP and lowers it
by 5-8 mV
Pk / PNa
Pk dominates / K+
K
Table 8.3 Comparison of Graded Potential and Action Potential in Neurons
- Action potentials are not degraded over distance.
- Regenerated in each patch of membrane along an
axon by action of ______ ______ ______ channels.
voltage gated ion
Fig. 8.7 ESSENTIALS Graded potentials
Electrical Signals: Ion Movement
______ channels control ion permeability
* Mechanically gated
* Chemical gated
* Voltage gated
Two voltage gated channels are important for the Action
Potential!
* ______ voltage gated ______ channel.
Responds ______ to depolarizing membrane potential
* ______ voltage gated ______ channel
Responds ______ to depolarizing membrane potential
Gated
Fast / sodium (Na+)
rapidly
Slow / potassium (K+)
slowly
Na+ channels have two gates: ______ and ______ gates.
activation and inactivation
Fig. 8.9 ESSENTIALS the action potential
Fig. 8.10 The voltage-gated channel
(a) At resting membrane potential, the activation gate closes the channel.
(b) depolarizing stimulus arrives at the channel - activation gate opens.
(c) Sodium enters the cell
(d) Approx EQUILIBRIUM POTENTIAL for sodium (Na) +30 - The inactivation gate closes and Na+ entry stops.
Fig. 8.11 Positive feedback
The addition of positive charge further depolarizes the inside of the cell and starts a positive feedback loop [p. 16] (Fig. 8.11). More Na+ channels open, and more Na+ enters, further depolarizing the cell. As long as the cell remains depolarized, activation gates in Na+ channels remain open.
Fig. 8.12 Refractory periods following an action potential
Action potentials will not fire during an ______ ______ period.
absolute refractory
Electrical Signals: Trigger Zone
______ ______ enters trigger zone.
* Voltage-gated ______ channels open and ______ enters axon.
* Positive charge spreads along adjacent sections of
axon by local current flow.
* Local current flow causes new section of the membrane to depolarize.
* The ______ period prevents ______ ______; loss of ______ repolarizes the membrane.
Graded potentials / Na+ / Na+ / refractory / backward conduction / K+
A ______ stimulus releases little neurotransmitter.
A ______ stimulus causes more action potentials and releases more neurotransmitter.
weak / strong
Speed of action potential in neuron influenced by what two things?
(1) Diameter of axon - Larger axons are faster.
(2) Resistance of axon membrane to ion leakage out of the cell - Myelinated axons are faster.
MS is autoimmune disease where the immune system attacks myelin.
Electrical synapses, or gap junctions, are different
from chemical synapses because they couple
neurons electrically.
* The two neurons are connected by membrane
proteins called connexons that form a tunnel
through which ions (current!) and small molecules
can pass.
* Transmission at electrical synapses is very fast and
bidirectional.
* Can synchronize cells so they “act as one.”
Fig. 8.19(a) ESSENTIALS Synaptic communication
Fig. 8.23 ESSENTIALS Fast and Slow Postsynaptic Responses
Ionotropic: Chemically gated ion channel
Metabotropic: G-protein coupled receptor
Fig. 8.20 Synthesis and recycling of acetylcholine
Dopamine mediates sense of pleasure and “reward”
* Cocaine elevates dopamine by blocking reuptake.
* Methamphetamines reduce dopamine.
