Bio Chapters 16-19 :)

Flashcards covering the functions, divisions, tissues, and structures of the human nervous system based on Chapter 16 lecture notes.

Sensory Function

The process where sensory receptors detect stimuli and send signals through the Peripheral Nervous System (PNS) to the Central Nervous System (CNS).

Integration

The function of the CNS where information is processed, memories are stored, and a response is decided based on sensory input.

Motor Function

The process where the CNS sends commands through the PNS to muscles, glands, or organs to trigger an action.

Central Nervous System (CNS)

The division of the nervous system that includes the brain and spinal cord, responsible for processing information and coordinating responses.

Peripheral Nervous System (PNS)

Consists of nerves outside the CNS that transmit signals between the brain/spinal cord and the rest of the body.

Somatic Nervous System (SNS)

A division of the PNS that controls skin, skeletal muscles, and tendons; it is mostly voluntary but includes automatic reflex arcs.

Autonomic Nervous System (ANS)

An involuntary division of the PNS that regulates cardiac muscle, smooth muscle, organs, and glands.

Sympathetic Division

The 'Fight or Flight' branch of the ANS that prepares the body for emergencies, increases heart rate, and uses the neurotransmitter norepinephrine (NE).

Parasympathetic Division

The 'Rest & Digest' branch of the ANS that promotes relaxation, slows heart rate, and uses the neurotransmitter acetylcholine (Ach).

Acetylcholine (ACh)

A neurotransmitter essential for memory circuits and muscle activation.

GABA

The main inhibitory neurotransmitter in the CNS that reduces nerve activity.

Neurons

The functional units of the nervous system responsible for transmitting nerve impulses.

Neuroglia

Cells that support and nourish neurons; examples include Microglia, Astrocytes, and Oligodendrocytes in the CNS.

Schwann cells

Cells in the PNS that produce the myelin sheath for peripheral nerves.

Oligodendrocytes

Cells in the CNS that form the myelin sheath.

Interneurons

Neurons found only in the CNS that receive, process, and integrate sensory information before sending a response.

Axon

The portion of a neuron that conducts nerve impulses.

Dendrites

Short extensions off the cell body that receive signals from sensory receptors or other neurons.

Myelin Sheath

A protective covering made of lipids and proteins that wraps around some axons to increase the speed of nerve impulse transmission.

Nodes of Ranvier

Small gaps between myelin sheaths that allow for faster signal conduction.

Resting Membrane Potential

The electrical charge of a nerve cell when not sending a signal, measured at approximately $-70\,mV$.

Depolarization

The rising phase of an action potential where sodium ($Na^+$) channels open and charge moves toward $+30\,mV$.

Repolarization

The falling phase of an action potential where sodium channels close and potassium ($K^+$) channels open, bringing the charge back toward negative.

Hyperpolarization

The recovery phase where the neuron briefly becomes more negative than the resting potential before the $Na^+/K^+$ pump restores $-70\,mV$.

Saltatory Conduction

The method of signal transmission in myelinated axons where action potentials jump between nodes of Ranvier.

Synaptic cleft

The small gap that separates a sending neuron from a receiving neuron at a synapse.

Meninges

Three protective bone layers around the CNS.

Cerebrospinal Fluid (CSF)

Fluid that provides cushioning and nutrients to the brain and spinal cord.

Cerebrum

The largest part of the brain, responsible for processing sensory input, voluntary movement, and integrating thought and emotions.

Corpus callosum

The structure that connects the two hemispheres of the cerebrum.

Frontal Lobe

The cerebral lobe that controls thinking, decision-making, movement, and speech.

Parietal Lobe

The cerebral lobe that processes touch, pain, temperature, and spatial awareness.

Temporal Lobe

The cerebral lobe involved in hearing, memory, and language comprehension.

Occipital Lobe

The cerebral lobe responsible for vision processing.

Thalamus

A structure in the diencephalon that relays sensory information to the cerebrum.

Hypothalamus

A brain structure that regulates hunger, thirst, temperature, hormones, and sleep.

Pineal Gland

Produces melatonin to regulate sleep.

Cerebellum

Located under the occipital lobe, it controls posture, balance, and fine-tunes motor skills.

Medulla Oblongata

Part of the brainstem that regulates heartbeat, breathing, and reflexes like coughing and swallowing.

Limbic System

A group of brain structures (including the amygdala and hippocampus) involved in emotion, memory, and motivation.

Hippocampus

A part of the limbic system essential for learning and memory.

Amygdala

A part of the limbic system involved in fear and emotional reactions.

Gray Matter

The middle portion of the spinal cord that contains cell bodies and processes information.

White Matter

Portion of the spinal cord containing myelinated axons that form tracts to send signals.

Spinal Nerves

31 pairs of mixed nerves that emerge from the spinal cord to connect the CNS to limbs and organs.

Cranial Nerves

12 pairs of nerves that emerge directly from the brain and serve the head, neck, and internal organs.

Vagus nerve (X)

A cranial nerve that controls the heart, digestion, and breathing.

Optic nerve (II)

A cranial nerve responsible for vision.

Sensory receptors

Specialized cells or nerve endings that detect and respond to specific environmental stimuli by converting them into electrical signals (nerve impulses).

Sensory transduction

The process where sensory receptors convert environmental stimuli into nerve impulses.

Exteroceptors

Sensory receptors that respond to external stimuli such as touch, temperature, pain, and special senses.

Interoceptors

Sensory receptors that detect internal body conditions, including blood pressure, chemical levels, and internal pain.

Proprioceptors

Mechanoreceptors located in muscles, tendons, joints, and the inner ear that detect body position and movement to help maintain muscle tone and balance.

Mechanoreceptors

Receptors that detect mechanical forces such as touch, pressure, vibration, stretch, hearing, and balance.

Thermoreceptors

Receptors specialized to detect temperature changes, specifically hot or cold.

Nociceptors

Pain receptors that detect damaging stimuli like extreme temperatures, mechanical force, or chemicals.

Photoreceptors

Sensory receptors found in the retina that detect light for vision.

Chemoreceptors

Receptors that detect chemical stimuli such as smell, taste, blood $pH$, and oxygen levels.

Free nerve endings

Unencapsulated structures that detect pain, temperature, and some touch.

Encapsulated nerve endings

Receptors surrounded by connective tissue designed to enhance sensitivity, such as Pacinian corpuscles for deep pressure.

Specialized receptor cells

Separate cells that synapse with sensory neurons, such as photoreceptors in the eye or hair cells in the ear.

Sensation

The process of detecting, transmitting, and interpreting stimuli from the environment or body leading to conscious awareness.

Perception

The conscious awareness of a sensation created when the cerebral cortex interprets sensory signals.

Sensory adaptation

A decrease in the response of sensory receptors to a constant stimulus over time to prevent sensory overload.

Somatic sensations

Sensory signals associated with the skin, muscles, joints, and internal organs (viscera).

Cutaneous Receptors

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

Prostaglandins

Chemicals released by damaged tissues that bind to nociceptors to signal pain.

Gustation

The technical term for the sense of taste.

Olfaction

The technical term for the sense of smell.

Primary Tastes

The five tastes detected by humans: Sweet, Sour, Bitter, Salty, and Umami (savory).

Papillae

The visible bumps on the tongue where taste buds are primarily located.

Olfactory Epithelium

A layer of tissue in the roof of the nasal cavity containing olfactory cells.

Flavor perception

The combined effect of taste and smell, where smell accounts for approximately $80\%$ of what we perceive as taste.

Sclera

The white, fibrous outer layer of the eye that provides protection and support.

Cornea

The clear, front part of the sclera that allows light to enter the eye and refracts light rays.

Choroid

The middle layer of the eye containing dark pigment to absorb stray light and prevent scattering.

Iris

The structure that regulates the amount of light entering the eye by controlling the size of the pupil.

Ciliary body

A structure that holds the lens in place and controls its shape for focusing (accommodation).

Retina

The innermost layer of the eye containing the photoreceptors (rods and cones) for sight.

Aqueous humor

The watery fluid located in the anterior compartment of the eye in front of the lens.

Vitreous humor

The fluid in the posterior compartment of the eye that maintains eye shape and holds the retina in place.

Rods

Photoreceptors that are very sensitive to light and make black-and-white vision possible, especially in low light.

Cones

Photoreceptors that require bright light and are responsible for color vision.

Fovea centralis

The part of the retina that makes acute (sharp) vision possible.

Visual Accommodation

The process of the lens changing shape to focus on objects at different distances; the lens is flat for distant objects and round/thick for near objects.

Blind Spot

The area where the optic nerve exits the eye; it lacks photoreceptors and detects no visual information.

Nearsightedness (Myopia)

A condition where distant objects appear blurry because the eye is elongated, causing light to focus in front of the retina.

Farsightedness (Hyperopia)

A condition where close objects appear blurry because the eye is too short, causing light to focus behind the retina.

Astigmatism

Blurred or distorted vision due to an unevenly shaped cornea or lens that causes improper light refraction.

Pinna / Auricle

The visible part of the outer ear that collects and directs sound waves into the auditory canal.

Tympanic Membrane

The eardrum, which vibrates in response to sound waves and transmits them to the middle ear.

Ossicles

Three small bones in the middle ear (malleus, incus, and stapes) that amplify and transfer sound vibrations.

Eustachian Tube

A tube that equalizes air pressure across the tympanic membrane.

Cochlea

A spiral-shaped, fluid-filled structure in the inner ear that converts sound vibrations into nerve impulses.

Organ of Corti

The structure within the cochlea containing hair cells (sensory receptors) that detect sound vibrations.

Vestibule

The central part of the inner ear containing the utricle and saccule, which detect linear movement and head position for balance.

Semicircular Canals

Three fluid-filled loops oriented along different axes ($x$, $y$, and $z$) that detect rotational (angular) movement.

Crista ampullaris

The sensory structure within each semicircular canal that contains hair cells to detect fluid movement.

Gland

A structure made up of one or more cells that make and secrete chemical substances.

Exocrine Gland

A gland that secretes substances through a duct that opens to an external environment (EXO = OUTSIDE).