Behavioural Biology B11: The Nervous System - Your CNS & PNS

Flashcards covering the organization, protection, cells, and major components of the Central Nervous System (CNS) and Peripheral Nervous System (PNS), including sensory and motor divisions.

Central Nervous System (CNS)

Consists of the brain and spinal cord; integrates incoming information and coordinates all voluntary and involuntary nervous functions.

Peripheral Nervous System (PNS)

Consists of ganglia and nerves that branch from the CNS; keeps the CNS in contact with the rest of the body.

Sensory Input

Information received from sensory receptors responding to external stimuli, skin, muscles, joints, and internal organs.

Somatic Nervous System

Directs voluntary movements by stimulating skeletal muscles.

Autonomic Nervous System

Regulates involuntary bodily activities such as heart rate, breathing rate, and digestive activities by controlling cardiac and smooth muscles, and glands.

Parasympathetic Nervous System

A subdivision of the autonomic nervous system that governs bodily activities during restful conditions ('rest and digest').

Sympathetic Nervous System

A subdivision of the autonomic nervous system that prepares the body for stressful or emergency situations ('fight or flight').

Neurons (nerve cells)

Excitable cells that generate and transmit messages.

Neuroglial cells (glial cells)

Outnumber neurons and provide structural support, growth factors, and insulating sheaths around axons (e.g., Schwann cells).

Nerve

Bundles of myelinated axons; predominant structures in the PNS.

Meninges

Three connective tissue membranes that protect the brain and spinal cord, consisting of the dura mater, arachnoid, and pia mater.

Dura mater

The outermost layer of the meninges.

Arachnoid

The middle layer of the meninges.

Pia mater

The innermost layer of the meninges.

Meningitis

Inflammation of the meninges, caused by bacteria and viruses, which can lead to encephalitis.

Cerebrospinal fluid (CSF)

Fluid that cushions the brain and spinal cord, provides shock absorption, support, nourishment, and waste removal.

Blood-brain barrier

Formed by tight junctions between cells in capillary walls supplying the CNS; protects the CNS by selectively controlling substances that enter the cerebrospinal fluid.

Cerebrum

The thinking, conscious part of the brain that accounts for 83% of total brain weight, separated into two hemispheres.

Corpus callosum

A band of white matter that connects the two cerebral hemispheres, allowing them to communicate.

Thalamus

The relay station of the brain for all sensory information (except smell), also directs motor activity and memory.

Hypothalamus

Maintains homeostasis by regulating vital bodily functions (e.g., heart rate, blood pressure, temperature, food intake); also a center for emotions and the 'master biological clock'.

Cerebellum

Integrates information from the motor cortex and sensory pathways to produce smooth, well-timed voluntary movements; controls equilibrium and posture.

Brainstem

Includes the Midbrain, Pons, and Medulla oblongata; relays information, integrates sensory input, and controls vital life functions.

Midbrain

Processes information about sights and sounds; controls simple reflex responses to these stimuli.

Pons

A 'bridge' that connects the spinal cord and cerebellum with the cerebrum, thalamus, and hypothalamus; assists the medulla in regulating respiration.

Medulla oblongata

Contains reflex centers to regulate breathing rhythm, heart rate, and blood pressure; serves as the pathway for sensory and motor messages.

Cerebral cortex

The thin outer layer of gray matter on each cerebral hemisphere, responsible for sensory, motor, and association functions.

Gray matter

Includes neuroglial cells, nerve cell bodies, and unmyelinated axons; found in the cerebral cortex and central spinal cord.

White matter

Consists mostly of myelinated axons, allowing for communication between various areas of the brain, and between the brain and spinal cord.

Frontal lobe

A lobe of the cerebral cortex involved in reasoning, thinking, voluntary movement, and association functions.

Parietal lobe

A lobe of the cerebral cortex containing the primary somatosensory area.

Temporal lobe

A lobe of the cerebral cortex involved in hearing and olfaction.

Occipital lobe

A lobe of the cerebral cortex primarily involved in vision.

Primary somatosensory area

A sensory area in the cerebral cortex that receives sensory information from the body.

Primary motor area

A motor area in the cerebral cortex that controls the skeletal muscles.

Premotor cortex

A motor area in the cerebral cortex that coordinates learned motor skills.

Prefrontal cortex

An association area in the cerebral cortex that enables reasoning and thinking.

Basal Ganglia (Basal Nuclei)

Millions of cell bodies organized into groups deep in the cerebrum that help execute and suppress desired voluntary motor behaviors.

Limbic System

Several brain structures (including the hippocampus and amygdala) that produce emotions and are involved in memory storage and retrieval.

Reticular Activating System (RAS)

An extensive network of neurons that runs through the medulla and projects to the cerebral cortex, filtering sensory input and keeping the cerebral cortex in an alert state.

Spinal cord

Part of the CNS, found within the vertebral column, responsible for conducting sensory and motor information and acting as a reflex center.

Dorsal horns

Regions of gray matter in the spinal cord that contain cell bodies of interneurons and receive information from sensory neurons.

Ventral horns

Regions of gray matter in the spinal cord that contain cell bodies of motor neurons of the somatic nervous system, sending information out via the ventral root.

Dorsal root ganglion

A cluster of sensory neuron cell bodies located outside the spinal cord.

Sensory (afferent) tracts

Myelinated fiber tracts in spinal cord white matter that conduct impulses toward the brain.

Motor (efferent) tracts

Myelinated fiber tracts in spinal cord white matter that carry impulses from the brain to skeletal muscles.

Ganglia (PNS)

Collections of nerve cell bodies located in the Peripheral Nervous System.

Cranial nerves

12 pairs of nerves in the PNS that take electrical impulses to and from the brain, primarily serving the head and neck.

Spinal nerves

31 pairs of mixed nerves in the PNS that extend from the spinal cord, each servicing a specific body region.

Dorsal root

The bundle of sensory fibers entering the dorsal side of the spinal cord.

Ventral root

The bundle of axons of motor neurons leaving the ventral side of the spinal cord.

Cauda equina

A collection of spinal nerves at the inferior end of the spinal cord.

Sensory Receptors

Specialized structures, often dendritic ends of sensory neurons, that respond to changes in the environment (stimuli).

Cutaneous receptors

Sensory receptors located in the skin that detect touch, pain, temperature, and pressure.

Proprioceptors

Sensory receptors located in muscles and tendons that detect stretch and tension.

Mechanoreceptors

Receptors that respond to touch, pressure, vibration, and stretch.

Thermoreceptors

Receptors sensitive to changes in temperature.

Photoreceptors

Receptors that respond to light energy (e.g., in the retina).

Chemoreceptors

Receptors that respond to chemicals (e.g., smell, taste, changes in blood chemistry).

Nociceptors

Receptors sensitive to pain-causing stimuli (e.g., extreme heat or cold, excessive pressure).

Motor Division of the PNS

The part of the PNS that consists of motor nerves, divided into the Somatic and Autonomic Nervous Systems.