Animal Nervous Systems Overview

Nervous System

Allows animals to sense and respond to environment.

Neuron

Basic functional unit of the nervous system.

Peripheral Nervous System

Includes nerves outside the brain and spinal cord.

Central Nervous System

Consists of the brain and spinal cord.

Sensory Receptors

Detect stimuli through changes in membrane potential.

Brain

Integrates information from various sensory sources.

Dendrites

Receive signals from other neurons.

Cell Body

Contains the nucleus and organelles of a neuron.

Axon

Transmits electrical signals away from the cell body.

Sensory Neurons

Send information about external and internal environments.

Interneurons

Process information and transmit it to other regions.

Motor Neurons

Produce motor responses based on received information.

Action Potential

Brief electrical signal transmitted along axon branches.

Neurotransmitters

Chemical signals used for neuron communication.

Membrane Potential

Charge difference across a neuron's plasma membrane.

Resting Membrane Potential

Negative voltage across the membrane at rest.

Na+/K+ Pump

Maintains resting membrane potential by ion movement.

Depolarization

Membrane becomes less negative during excitation.

Threshold Potential

Membrane potential needed to trigger an action potential.

All-or-None Principle

Action potentials do not vary in strength.

Frequency Coding

Information is coded by action potential frequency.

Glial Cells

Support neurons without transmitting electrical signals.

Action Potential Propagation

Travels unidirectionally towards axon terminals.

Saltatory propagation

Fast transmission of action potentials along axons.

Hodgkin & Huxley

Researchers who studied action potentials in squid axons.

Synapse

Junction where neurons communicate via chemical signals.

Postsynaptic membrane

Membrane receiving signals from neurotransmitters.

Voltage-gated Na+ channels

Channels that open during action potential depolarization.

Excitatory synapses

Transmit relevant information between nerve cells.

Inhibitory synapses

Filter out unimportant information between neurons.

EPSP

Excitatory Post-Synaptic Potential, increases membrane potential.

IPSP

Inhibitory Post-Synaptic Potential, decreases membrane potential.

Temporal summation

Summation of EPSPs/IPSPs over time.

Spatial summation

Summation of EPSPs/IPSPs across different locations.

Nervous system organization

Structure coordinating responses to sensory information.

Central Nervous System

Includes brain and spinal cord.

Cerebral cortex

Region governing advanced cognitive functions.

Frontal lobe

Responsible for decision-making and planning.

Parietal lobe

Involved in body awareness and spatial orientation.

Temporal lobe

Processes auditory information and sound.

Occipital lobe

Responsible for processing visual information.

Gray matter

Superficial layer of cortex with densely packed neurons.

Neuronal surface area

Highly folded cortex increases neuron capacity.

Neurotransmitter-filled vesicles

Fuse with postsynaptic membrane during signal transmission.

Cerebral cortex

Outer layer of the brain, involved in complex functions.

White matter

Myelin-covered axons facilitating communication in the brain.

Thalamus

Relays sensory information to the cerebral cortex.

Hypothalamus

Regulates autonomic nervous system and endocrine functions.

Cerebellum

Coordinates complex motor tasks and integrates sensory information.

Peripheral Nervous System

Connects the central nervous system to limbs and organs.

Somatic division

Controls voluntary movements and external stimuli responses.

Autonomic division

Regulates involuntary bodily functions without conscious awareness.

Sympathetic nervous system

Prepares body for 'fight or flight' response.

Parasympathetic nervous system

Promotes 'rest and digest' functions.

Sensory receptors

Detect environmental stimuli and convert them to signals.

Chemoreceptors

Detect chemical stimuli and cause cell depolarization.

Mechanoreceptors

Respond to physical forces and open ion channels.

Photoreceptors

Convert light energy into electrical signals in the eye.

Gustatory cells

Taste receptors responding to chemicals in saliva.

Olfactory cells

Smell receptors responding to chemical odors.

Rods

Photoreceptors for low-light vision, detect shades of gray.

Cones

Photoreceptors for color vision, sensitive to light wavelengths.

Single-lens eyes

Provide sharp images by focusing light on photoreceptors.

Statoliths

Starch-filled organelles aiding plant gravity orientation.

Sensory transduction

Conversion of physical stimuli into action potentials.

Action potential

Electrical signal generated by neuron response to stimuli.

Eye comparison

Differences in visual systems among various species.

Inhibitory synapses

Filter out unimportant information from signals.

EPSP

Excitatory Post-Synaptic Potential.

IPSP

Inhibitory Post-Synaptic Potential.

Temporal summation

Summation of signals over time.

Spatial summation

Summation of signals over space.

Nervous system organization

Includes central and peripheral components.

Central Nervous System

Comprises the brain and spinal cord.

Peripheral Nervous System

Includes cranial and spinal nerves.

Somatic division

Voluntary control of body movements.

Autonomic division

Involuntary control of internal functions.

Sympathetic nervous system

Prepares body for 'fight-or-flight' response.

Parasympathetic nervous system

Promotes 'rest-and-digest' functions.

Cerebral cortex

Governs advanced cognitive functions.

Parietal lobe

Involved in body awareness.

Temporal lobe

Processes auditory information.

Occipital lobe

Processes visual information.

Gray matter

Densely packed neuron cell bodies.

White matter

Myelin-covered axons facilitating communication.

Thalamus

Relays sensory information to the cortex.

Hypothalamus

Regulates autonomic and endocrine functions.

Cerebellum

Coordinates complex motor tasks.

Sensory receptors

Detect environmental physical properties.

Chemoreceptors

Detect chemical stimuli in the environment.

Mechanoreceptors

Detect physical forces and pressure.

Photoreceptors

Detect light and convert it to signals.

Gustatory cells

Respond to chemicals in saliva for taste.

Olfactory cells

Respond to chemical odors for smell.

Rods

Detect light intensity; sensitive in low light.

Cones

Detect color; sensitive to specific light wavelengths.

Opsin

Light-sensitive protein in photoreceptors.

Statoliths

Provide plant roots orientation relative to gravity.