Nervous System and Sensory Receptors

A comprehensive set of flashcards covering the anatomy and functions of the nervous system, sensory receptors, and the brain structure.

Nervous System

Main functions include communication with the body and coordination of body movements.

Neurons

Nerve cells that act as the functional units of the nervous system, propagating action potentials or electrical impulses.

Nervous System

Main functions include communication with the body and coordination of body movements.

Neurons

Nerve cells that act as the functional units of the nervous system, propagating action potentials or electrical impulses.

Neuroglia

Support cells in the nervous system that do not conduct electrical impulses but assist neurons.

Central Nervous System (CNS)

Consists of the brain and spinal cord.

Peripheral Nervous System (PNS)

Includes all nervous tissue outside the CNS, such as cranial and spinal nerves.

Somatic Nervous System

Part of the PNS that controls skeletal muscle and is under conscious control.

Autonomic Nervous System

Part of the PNS that controls smooth muscle, cardiac muscle, and glands, functioning automatically.

Afferent Neurons

Neurons that carry impulses toward the CNS.

Efferent Neurons

Neurons that carry impulses away from the CNS.

Dendrites

Structures that receive information and convey it to the neuron’s nucleus.

Axon

Structure that transmits information away from the neuron’s cell body.

Myelin

An insulating sheet made of fat, not present in all neurons, which speeds up electrical impulses.

Schwann Cells

Neuroglia in the PNS that produce myelin for peripheral axons.

Gray Matter

Regions of the CNS that contain neuronal cell bodies and are devoid of myelin.

Nodes of Ranvier

Gaps in the myelin sheath that are critical for the propagation of action potentials.

Multipolar Neuron

Neurons with many dendrites and one axon; the most common type (99%) in the CNS.

Bipolar Neuron

Neurons with two extensions (one axon and one dendrite) from the cell body.

Unipolar Neuron

Neurons with one process that splits into two branches; primarily found in PNS ganglia.

Astrocytes

Neuroglia that connect neurons to blood vessels and exchange nutrients.

Oligodendrocytes

Neuroglia in the CNS that produce myelin and provide structural support.

Microglia

Phagocytic neuroglia that clean up cellular debris in the CNS.

Ependymal Cells

Ciliated cells that line the central canal of the spinal cord and ventricles of the brain.

Resting Neuron Potential

The electrical potential of a neuron at rest, typically around -70 mV.

Voltage Gated Channels

Ion channels that open in response to changes in membrane potential.

Threshold Stimulus

The minimum stimulus required to trigger an action potential, usually around -55 mV.

Depolarization

The process where sodium ions enter the neuron, making the inside positive up to 30 mV.

Repolarization

The process where potassium ions exit the neuron, restoring the negative internal charge.

Hyperpolarization

When the membrane potential falls below -70 mV due to excessive potassium exiting the cell.

Synapse

The junction between two neurons where neurotransmitters are released.

Neurotransmitters

Chemicals that transmit signals across the synapse between neurons.

Excitatory Neurotransmitters

Substances that bring the postsynaptic membrane closer to action potential.

Inhibitory Neurotransmitters

Substances that push the postsynaptic membrane further from action potential.

Convergence

When multiple neurons send signals to one neuron.

Divergence

When one neuron sends signals to multiple neurons.

Meninges

Three layers of protective tissue that cover the brain and spinal cord.

Dura Mater

The outermost layer of the meninges, made of dense connective tissue.

Arachnoid Mater

The middle layer of the meninges, web-like in structure.

Pia Mater

The innermost layer of the meninges directly attached to the brain.

Cerebrospinal Fluid (CSF)

Fluid that cushions the brain, produced by ventricles and reenters by arachnoid granulations.

Cerebrum

The largest part of the brain responsible for sensory perception and movement.

Cerebellum

Part of the brain that coordinates voluntary movements and balance.

Brainstem

The part of the brain that controls basic life functions and connects to the spinal cord.

Thalamus

A brain structure that relays sensory and motor signals to the cerebral cortex.

Hypothalamus

Brain region that controls autonomic functions and maintains homeostasis.

Reflex Arc

The neural pathway involved in a reflex action, typically involving sensory and motor neurons.

Dermatome

An area of skin served by a specific spinal nerve.

Cauda Equina

A bundle of spinal nerves extending below the spinal cord.

Cranial Nerves

Twelve pairs of nerves that originate from the brain, mostly mixed nerves.

Spinal Nerves

Nerves that arise from the spinal cord, consisting of both sensory and motor fibers.

Sensory Receptors

Specialized structures that convert environmental stimuli into nerve impulses.

Chemoreceptors

Receptors that respond to chemical changes such as taste and smell.

Mechanoreceptors

Receptors that respond to mechanical forces, such as touch and pressure.

Thermoreceptors

Receptors that detect changes in temperature.

Photoreceptors

Visual receptors in the eyes that respond to light.

Taste Buds

Structures on the tongue that contain sensory receptors for taste.

Olfaction

The sense of smell involving olfactory receptors in the nasal cavity.

Cochlea

A spiral-shaped organ in the inner ear responsible for hearing.

Vestibular System

Part of the inner ear involved in balance and spatial orientation.

Efferent Neurons

Also known as motor neurons, conducting impulses away from the CNS.

Craniosacral Division

The part of the parasympathetic nervous system that originates in the brainstem and sacral region.

Sympathetic Division

Part of the autonomic nervous system responsible for the 'fight or flight' response.

Parasympathetic Division

Part of the autonomic nervous system that promotes 'rest and digest' activities.

Preganglionic Fibers

Fibers that carry impulses from the CNS to autonomic ganglia.

Postganglionic Fibers

Fibers that carry impulses from autonomic ganglia to effector organs.

Gray Rami

Nerve fibers that allow postganglionic fibers to return to the spinal nerve.

Sympathetic Chain Ganglia

A series of interconnected ganglia located close to the spinal cord.

Collateral Ganglia

Sympathetic ganglia located further away from the spinal cord.

Homeostasis

The maintenance of stable internal conditions despite external changes.

Autonomic Nervous System (ANS)

A division of the PNS that controls involuntary bodily functions.

Ganglia

Clusters of nerve cell bodies located in the PNS.

Phrenic Nerve

A nerve originating from the cervical plexus that controls the diaphragm.

Utricle and Saccule

Structures in the inner ear involved in balance and equilibrium.

What are preganglionic fibers?

Preganglionic fibers are the axons of neurons that originate from the central nervous system (CNS) and extend to autonomic ganglia.

What are postganglionic fibers?

Postganglionic fibers are the axons of neurons that extend from the autonomic ganglia to the target organs or tissues.

What is the primary function of preganglionic fibers?

transmit signals from the CNS to autonomic ganglia.

What is the primary function of postganglionic fibers?

The primary function of postganglionic fibers is to carry signals from the autonomic ganglia to the target organs, eliciting a response.

How do preganglionic and postganglionic fibers differ in length?

Preganglionic fibers are typically longer than postganglionic fibers, particularly in the parasympathetic nervous system.

What is the brainstem?

is the portion of the brain connecting the brain to the spinal cord, responsible for regulating vital functions such as heart rate and breathing.

What are the three main parts of the brain?

cerebrum, cerebellum, and brainstem.

What is the function of the cerebellum?

responsible for coordination, balance, and fine motor control.

What is the cerebral cortex?

outer layer of the cerebrum, involved in higher brain functions such as thought, language, and problem-solving.

What role does the thalamus play in the brain?

acts as a relay station for sensory information, directing it to the appropriate areas of the brain for processing.