Nervoussystempresentation 1193558738696238 3

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Information about Nervoussystempresentation 1193558738696238 3

Published on November 7, 2007

Author: MARIANGG

Source: slideshare.net

The Nervous System (Chapter 48) Samuel Black, Glasha Marcon, Csilla T óth, Kina Winoto

Background Information Neuron = a nerve cell, makes up nerves Axon = a nerve fiber THEREFORE, a nerve is made of many axons and neurons

Neuron = a nerve cell, makes up nerves

Axon = a nerve fiber

THEREFORE, a nerve is made of many axons and neurons

Organization of Nervous Systems Nerves, which make up nervous systems, are organized in the following way…

Hierarchy of Nervous Systems: Peripheral Nervous System Somatic Nervous System Automatic Nervous System Sympathetic Division Parasympathetic Division Enteric Division

Peripheral Nervous

System

Central Nervous System (CNS) What is it? Simplest version = a small brain and longitudinal nerve cords BASICALLY, a brain and a mode of transporting “messages” to the brain (i.e. a spinal cord) Ganglia = segmentally arranged clusters of neurons (found in complex CNSs)

What is it?

Simplest version = a small brain and longitudinal nerve cords

BASICALLY, a brain and a mode of transporting “messages” to the brain (i.e. a spinal cord)

Ganglia = segmentally arranged clusters of neurons (found in complex CNSs)

Peripheral Nervous System (PNS) What is it? Nerves that connect the CNS with the rest of an organism’s body Examples: sensory receptors, spinal nerves, cranial nerves

What is it?

Nerves that connect the CNS with the rest of an organism’s body

Examples: sensory receptors, spinal nerves, cranial nerves

Somatic Nervous System What is it? It consists of peripheral nerve fibers that deliver sensory information to the CNS. It also consists of motor nerve fibers that extend to skeletal muscle.

What is it?

It consists of peripheral nerve fibers that deliver sensory information to the CNS.

It also consists of motor nerve fibers that extend to skeletal muscle.

Autonomic Nervous System (ANS) What is it? The ANS regulates the body’s internal environment by controlling smooth and cardiac muscles and vital organs. Examples: lungs, heart, intestines

What is it?

The ANS regulates the body’s internal environment by controlling smooth and cardiac muscles and vital organs.

Examples: lungs, heart, intestines

Sympathetic Division (part of the ANS) What is it? This division is activated during the “flight-or-fight” response as the heart beats faster, the liver converts glycogen to glucose, and the lungs adapt to support increased gas exchange. Examples/organs involved: heart, liver, lungs

What is it?

This division is activated during the “flight-or-fight” response as the heart beats faster, the liver converts glycogen to glucose, and the lungs adapt to support increased gas exchange.

Examples/organs involved: heart, liver, lungs

Parasympathetic Division (part of the ANS) What is it? This division promotes calming and a return to the “rest and digest” mode as the heart slows down, the liver starts creating more glycogen, and digestion begins. Examples/organs involved: heart, liver, stomach

What is it?

This division promotes calming and a return to the “rest and digest” mode as the heart slows down, the liver starts creating more glycogen, and digestion begins.

Examples/organs involved: heart, liver, stomach

Enteric Division (part of the ANS) What is it? It consists of networks of neurons in the digestive tracts, pancreas, and gallbladder. It controls these organs’ secretions. Examples/organs involved: intestines, pancreas, and gallbladder

What is it?

It consists of networks of neurons in the digestive tracts, pancreas, and gallbladder.

It controls these organs’ secretions.

Examples/organs involved: intestines, pancreas, and gallbladder

Information Processing: Typical Nerve Pathway Sensory input Integration (brain analyzes) Motor output

Reflexes 1 2 3 4 5 6

1

Neurons Dendrites Axon hillock Axon Myelin sheath Synaptic terminal

Message Sending in Neurons (summary) Message is received via dendrite Axon hillock creates a signal, usually a chemical messenger called a neurotransmitter. Signal travels down axon. Message is transferred to connected neuron via synaptic terminal

Message is received via dendrite

Axon hillock creates a signal, usually a chemical messenger called a neurotransmitter.

Signal travels down axon.

Message is transferred to connected neuron via synaptic terminal

Neurons from a chemical point of view Neurons, like all cells, have an electrical potential difference, or a voltage, across their plasma membrane. Or in other words, there is electricity in neurons.

Neurons, like all cells, have an electrical potential difference, or a voltage, across their plasma membrane. Or in other words, there is electricity in neurons.

Resting Potential What is it? The resting potential of a neuron is the voltage when the neuron is not transmitting signals Normal resting potential of a neuron is between -60 mV and -80 mV It is maintained by ionic gradients.

What is it?

The resting potential of a neuron is the voltage when the neuron is not transmitting signals

Normal resting potential of a neuron is between -60 mV and -80 mV

It is maintained by ionic gradients.

Resting Potential (continued) A closer look: Ion channels help maintain the resting potential of a neuron through the diffusion of K + and Na + . These channels are ALWAYS open to keep the potential at equilibrium.

A closer look:

Ion channels help maintain the resting potential of a neuron through the diffusion of K + and Na + . These channels are ALWAYS open to keep the potential at equilibrium.

Gated Ion Channels These channels open and close in response to stimuli. There are 3 types: Stretch-gated ion channels Ligand-gated ion channels Voltage-gated ion channels

These channels open and close in response to stimuli.

There are 3 types:

Stretch-gated ion channels

Ligand-gated ion channels

Voltage-gated ion channels

What is it? It is the signal that carry information along axons It only lasts 1-2 milliseconds Action Potential

What is it?

It is the signal that carry information along axons

It only lasts 1-2 milliseconds

Production of Action Potentials This process involves the opening and closing of many gates and is best represented with the following diagram…

This process involves the opening and closing of many gates and is best represented with the following diagram…

1. Resting state 2. Depolarization 3. Rising phase of the action potential 4. Falling phase of the action potential 5. Undershoot

1. Resting state

Action Potential in Axons 1 2 3

1

Action Potential in Axons (summary) In the axon hillock, an action potential is created and spreads Na + , which triggers the depolarization of the neighboring regions in the axon. From this depolarization, the action potential is started again, which yet again triggers depolarization in neighboring regions. This process is repeated down the length of the axon.

In the axon hillock, an action potential is created and spreads Na + , which triggers the depolarization of the neighboring regions in the axon.

From this depolarization, the action potential is started again, which yet again triggers depolarization in neighboring regions.

This process is repeated down the length of the axon.

Neurotransmitters Acetylcholine Most common neurotransmitter in invertebrates and vertebrates Biogenic amines Derived from amino acids, involved in indirect synaptic transmission Amino Acids Gamma aminobutyric acid, glycine, glutamate, and aspartate Gases NO and CO act as local regulators

Acetylcholine

Most common neurotransmitter in invertebrates and vertebrates

Biogenic amines

Derived from amino acids, involved in indirect synaptic transmission

Amino Acids

Gamma aminobutyric acid, glycine, glutamate, and aspartate

Gases

NO and CO act as local regulators

Impulse Propagation Each action potential is regenerated along the entire length of the axon through depolarization which triggers a new action potential Action potentials normally move in only one direction The speed at which an action potential propagates along an axon relates to the diameter of the axon (faster) and myelinated neurons which only depolarize at Ranvier nodes

Each action potential is regenerated along the entire length of the axon through depolarization which triggers a new action potential

Action potentials normally move in only one direction

The speed at which an action potential propagates along an axon relates to the diameter of the axon (faster) and myelinated neurons which only depolarize at Ranvier nodes

Neuron Communication Chemical Neurotransmitters A presynaptic neuron synthesizes a neurotransmitter and packages it in synaptic vesicles When an impulse reaches the terminal end it depolarizes the terminal membrane, opening voltage-gated calcium channels in the membrane. The increase in Ca 2+ causes the release of neurotransmitters by exocytosis

Chemical Neurotransmitters

A presynaptic neuron synthesizes a neurotransmitter and packages it in synaptic vesicles

When an impulse reaches the terminal end it depolarizes the terminal membrane, opening voltage-gated calcium channels in the membrane. The increase in Ca 2+ causes the release of neurotransmitters by exocytosis

The Synapse The following occurs at the synapse: After the Ca 2+ influx occurs the synaptic vesicles fuse with the presynaptic membrane The vesicles release neurotransmitters into the synaptic cleft The neurotransmitters bind to the open receptor of the ligand-gated ion channel Both Na + and K + then diffuse through the channels

The following occurs at the synapse:

After the Ca 2+ influx occurs the synaptic vesicles fuse with the presynaptic membrane

The vesicles release neurotransmitters into the synaptic cleft

The neurotransmitters bind to the open receptor of the ligand-gated ion channel

Both Na + and K + then diffuse through the channels

Graded Potentials Occurrences at synaptic inputs on cell bodies Excitatory postsynaptic potentials (EPSPs) When the membrane depolarizes in the presence of Na + and K + the membrane potential reaches a point between E Na and E K Brinings the membrane potential toward the threshold Inhibitory postsynaptic potentials (IPSPs) A different neurotransmitter only binds to K + selective channels The postsynaptic membrane hyperpolarizes, which moves the membrane further from the threshold

Occurrences at synaptic inputs on cell bodies

Excitatory postsynaptic potentials (EPSPs)

When the membrane depolarizes in the presence of Na + and K + the membrane potential reaches a point between E Na and E K

Brinings the membrane potential toward the threshold

Inhibitory postsynaptic potentials (IPSPs)

A different neurotransmitter only binds to K + selective channels

The postsynaptic membrane hyperpolarizes, which moves the membrane further from the threshold

Nervous System Variations Variations in nervous system occur throughout the animal kingdom Simplest nervous systems were radial around a gastrovascular cavity More complex systems contain nerve nets and nerves More evolved: Cephalization: centralization of nerves in brain with ganglia extensions

Variations in nervous system occur throughout the animal kingdom

Simplest nervous systems were radial around a gastrovascular cavity

More complex systems contain nerve nets and nerves

More evolved:

Cephalization: centralization of nerves in brain with ganglia extensions

Human Nervous System Diagram

The Human Brain The Brainstem Functions in homeostasis, coordination of movement, and conduction of information to higher brain centers Medulla oblongata Controls breathing, heart and blood vessel activity, swallowing, vomiting, and digestion Pons Works in conjunction with medulla: regulates breathing centers in medulla Midbrain Receipt and integration of sensory information, relays information to specific regions of forebrain, hearing (inferior colliculi) and vision (superior colliculi) Reticular formation (reticular activating system) Diffuse neuron network, which regulates sleep and arousal

The Brainstem

Functions in homeostasis, coordination of movement,

and conduction of information to higher brain centers

Medulla oblongata

Controls breathing, heart and blood vessel activity, swallowing, vomiting, and digestion

Pons

Works in conjunction with medulla: regulates breathing centers in medulla

Midbrain

Receipt and integration of sensory information, relays information to specific regions of forebrain, hearing (inferior colliculi) and vision (superior colliculi)

Reticular formation (reticular activating system)

Diffuse neuron network, which regulates sleep and arousal

The Cerebellum Important for coordination and error checking during motor, perceptual, and cognitive functions Involved with Learning Learned motor skills Coordinates movement and balance Hand-eye coordination The Diencephalon Develops into three adult regions Epithalamus Pineal gland Choroid plexus Capillaries Thalamus Main input center for motor information Information is sorted and sent to the appropriate region of the brain Receives information from the cerebrum and parts of the brain that regulate emotion and arousal Hypothalamus Homeostatic regulation Thermostat, sexual and mating behaviors, fight-or-flight, and pleasure

The Cerebellum

Important for coordination and error checking during motor, perceptual, and cognitive functions

Involved with

Learning

Learned motor skills

Coordinates movement and balance

Hand-eye coordination

The Diencephalon

Develops into three adult regions

Epithalamus

Pineal gland

Choroid plexus

Capillaries

Thalamus

Main input center for motor information

Information is sorted and sent to the appropriate region of the brain

Receives information from the cerebrum and parts of the brain that regulate emotion and arousal

Hypothalamus

Homeostatic regulation

Thermostat, sexual and mating behaviors, fight-or-flight, and pleasure

Circadian Rhythms Biological Clock (Suprachiasmatic nuclei) Hormone release Huger Heightened sensitivity

Biological Clock (Suprachiasmatic nuclei)

Hormone release

Huger

Heightened sensitivity

The Cerebrum Supports olfactory reception as well as audiotry and visual processing Divided into right and left cerebral hemispheres The left hemisphere controls and monitors the right side of the body The right hemisphere controls and monitors the left side of the body Outer covering of grey matter called cerebral cortex Most complex part of the brain Sensory information is analyzed Motor commands are issued Language is generated Internal white matter, and neurons called basal nuclei (deep within) Basal Nuclei Centers for planning and movement sequences The corpus callosum enables communication between the right and left cerebral cortices

The Cerebrum

Supports olfactory reception as well as audiotry and visual processing

Divided into right and left cerebral hemispheres

The left hemisphere controls and monitors the right side of the body

The right hemisphere controls and monitors the left side of the body

Outer covering of grey matter called cerebral cortex

Most complex part of the brain

Sensory information is analyzed

Motor commands are issued

Language is generated

Internal white matter, and neurons called basal nuclei (deep within)

Basal Nuclei

Centers for planning and movement sequences

The corpus callosum enables communication between

the right and left cerebral cortices

Lateralization of Cortical Function Right and left hemispheres become more adapt at certain skills Left Hemisphere Language, math, logic, and processing sequences Right Hemisphere Pattern recognition, face recognition, spatial relations, nonverbal thinking, emotional processing, and multi-tasking

Right and left hemispheres become more adapt at certain skills

Left Hemisphere

Language, math, logic, and processing sequences

Right Hemisphere

Pattern recognition, face recognition, spatial relations, nonverbal thinking, emotional processing, and multi-tasking

Brain Attributes Limbic system Amygdala, hippocampus, and olfactory bulb Deals with emotions Memory and Learning Short-term memory Long-term memory Long-term potentiation

Limbic system

Amygdala, hippocampus,

and olfactory bulb

Deals with emotions

Memory and Learning

Short-term memory

Long-term memory

Long-term potentiation

Nervous System Diseases and Disorders Schizophrenia Depression Alzheimer’s Disease Parkinson’s Disease

Schizophrenia

Depression

Alzheimer’s Disease

Parkinson’s Disease

Extra Credit Insect Nervous System Two main divisions Brain Ventral nerve cord Head capsule contains six pairs of ganglia, the first three pairs are fused into the brain The last three pairs are fused into the subesophageal ganglion The number of ganglia differs depending on the insect species: cockroaches have six ganglia in their abdomen

Insect Nervous System

Two main divisions

Brain

Ventral nerve cord

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