EEMB 7 - Chapter 38: Nervous and Sensory Systems

nerve net

a weblike system of neurons, characteristic of radially symmetric animals, such as hydras

nerves

a fiber composed primarily of the bundled axons of neurons

central nervous system (CNS)

the portion of the nervous system where signal integration occurs; in vertebrate animals, the brain and spinal cord

peripheral nervous system (PNS)

the sensory and motor neurons that connect to the central nervous system

reflexes

an automatic reaction to a stimulus, mediated by the spinal cord or lower brain

gray matter

regions of dendrites and clustered neuron cell bodies within the CNS.

white matter

tracts of myelinated axons within the CNS

motor system

an efferent branch of the vertebrate peripheral nervous system composed of motor neurons that carry signals to skeletal muscles in response to external stimuli; entirely within the CNS

autonomic nervous system

an efferent branch of the vertebrate peripheral nervous system that regulates the internal environment; unconscious sensory and motor functions

enteric nervous system

within the autonomic nervous system, a distinct network of neurons that exerts direct and partially independent control over the digestive tract, pancreas, and gallbladder

sympathetic division

a division of the autonomic nervous system; generally increases energy expenditure and prepares the body for action; "fight or flight" system

parasympathetic division

a division of the autonomic nervous system; generally enhances body activities that gain and conserve energy, such as digestion and reduced heart rate

biological clock

an internal timekeeper that controls an organism's biological rhythms; marks time with or without environmental cues but often requires signals from the environment to remain tuned to an appropriate period; regulated by the hypothalamus

lateralization

segregation of functions in the cortex of the left and right cerebral hemispheres

neuronal plasticity

the capacity of a nervous system to change with experience

short-term memory

the ability to hold information, anticipations, or goals for a time and then release them if they become irrelevant

long-term memory

the ability to hold, associate, and recall information over one's lifetime

sensory reception

the detection of a stimulus by sensory cells

sensory receptor

an organ, cell, or structure within a cell that responds to specific stimuli from an organism's external or internal environment

perception

the interpretation of sensory system input by the brain

amplification

the strengthening of stimulus energy during transduction; enables animals to detect and respond to weak stimuli

sensory adaptation

the tendency of sensory neurons to become less sensitive when they are stimulated repeatedly

mechanoreceptors

a sensory receptor that detects physical deformation in the body's environment associated with pressure, touch, stretch, motion, or sound by forms of mechanical energy

electromagnetic receptors

a receptor of electromagnetic energy, such as visible light, electricity, or magnetism

thermoreceptors

a receptor stimulated by either heat or cold

nociceptors

a sensory receptor that responds to noxious or painful stimuli; also called a pain receptor

chemoreceptors

a sensory receptor that responds to a chemical stimulus, such as a solute or an odorant

olfaction

the sense of smell

hair cells

a mechanosensory cell that alters output to the nervous system when hairlike projections on the cell surface are displaced; rely on these cells to detect motion

utricle

in the vertebrate ear, a chamber in the vestibule behind the oval window that opens into the three semicircular canals, detecting horizontal accelerations (e.g., car)

saccule

in the vertebrate ear, a chamber in the vestibule behind the oval window that participates in the sense of balance, detecting vertical accelerations (e.g., elevation)

photoreceptors

an electromagnetic receptor that detects the radiation known as visible light

compound eyes

a type of multifaceted eye in insects and crustaceans consisting of up to several thousand light-detecting, focusing ommatidia; effective at detecting movement

ommatidia

One of the facets of the compound eye of arthropods and some polychaete worms that has its own light-focusing lens that captures light from tiny part of visual field

single-lens eyes

the camera-like eye found in some jellies, polychaete worms, spiders, and many molluscs where light enters through pupil and iris expands or contracts to change diameter of pupil to let in more or less light

pupil

the opening in the iris, which admits light into the interior of the vertebrate eye; muscles in the iris regulate its size

functional imaging

allows medical personnel and researchers to match specific function with activity in certain areas of the brain by measuring changes in blood flow

arousal

state of awareness of external world

sleep

state in which external stimuli are received by not consciously perceived; an active state for your brain

limbic system

neural system located below the cerebral hemispheres; associated with emotions and drives

hypothalamus

the ventral part of the vertebrate forebrain; functions in maintaining homeostasis, especially in coordinating the endocrine and nervous systems; also known as the body's thermostat as it regulates body temperature to reach homeostasis

thalamus

an integrating center of the vertebrate forebrain; neurons with cell bodies in this area relay neural input to specific areas in the cerebral cortex and regulate what information goes to the cerebral cortex

amygdala

a limbic system structure involved in memory and emotion, particularly fear and aggression.

hippocampus

a neural center located in the limbic system; helps process explicit memories for storage

reward system

neuronal circuit in brain that is strongly influenced by emotion; dramatically affected by drug addiction

frontal lobe

involved with thinking or conscious action; associated with reasoning, social understanding, voluntary muscle movements, and learning & recalling information

parietal lobe

involved in sensory association (integration of sensory information), especially your sense of touch

temporal lobe

a region of the cerebral cortex responsible for hearing (auditory cortex) and language (wernicke's area)

occipital lobe

a region of the cerebral cortex that processes visual information

broca's area

controls language expression (speaking); an area, usually in the left frontal lobe, that directs the muscle movements involved in speech

wernicke's area

controls language reception (understanding language); a brain area involved in language comprehension and expression; usually in the left temporal lobe

left hemisphere

controls language, math, and logic

right hemisphere

controls the left side of the body; creative, intuitive, spacial

order of sensory processing

reception, tranduction, perception, and adaptation

sensory transduction

conversion of a sensory stimulus into electrical energy in the nervous system by a change in the membrane potential

transmission

when sensory information travels through nervous system as nerve impulses or action potential

light-detecting organs

1. ocelli (eyespots) in head region

2. photoreceptors in each ocellus receive light through opening where there are no pigmented cells

3. the organism compares AP coming from two ocelli and can therefore move away from light if it wants to hide

rods

retinal receptors that are highly sensitive to light so they detect black, white, and gray; necessary for peripheral and night vision, when cones don't respond

cones

retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions; detect fine detail and give rise to color sensations.

retina

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

visual field

brain processes visual information and controls what information is captured

statocysts

a type of mechanoreceptor that functions in equilibrium in invertebrates by use of statoliths, which stimulate hair cells in relation to gravity

main functions of CNS

receive sensory signals (relay), process information, and send out motor signals (response)

type of neurons in CNS

interneurons

main functions of PNS

controls senses, movement, and unconscious processing

symptoms of sympathetic nerves

dilate pupils, inhibit salivation, increase heartbeat, dilated airways, inhibit stomach activities, inhibit gallbladder, inhibit intestine activites, secrete epinephrine & norepinephrine, and relax bladder

symptoms of parasympathetic nerves

constrict pupils, stimulate salivation, slow heartbeat, constrict airways, stimulate stomach activities, stimulate gallbladder, stimulate intestine activities, contract bladder, and stimulate genitals

iris

the colored part of the vertebrate eye, formed by the anterior portion of the choroid, that changes the diameter of the pupil to let in more or less light

cerebrum

the dorsal portion of the vertebrate forebrain, composed of right and left hemispheres; the integrating center for memory, learning, emotions, and other highly complex functions of the central nervous system

cerebellum

part of the vertebrate hindbrain located dorsally; functions in unconscious coordination of movement and balance; helps in learning and remembering motor skills and receives sensory information

outer ear function

collecting sound waves and sending it to the eardrum through the auditory canal

middle ear function

converts air pressure waves to fluid pressure waves

inner ear function

hearing and equilibrium

cerebrospinal fluid

the fluid in and around the brain and spinal cord that serves as a filtrate of the blood

blood-brain barrier

a filtering mechanism of the capillaries that carry blood to the brain and spinal cord tissue, blocking the passage of certain substances

afferent neuronal systems

the part of the nervous system that carries sensory information from the body to the central nervous system; these neurons help detect stimuli such as touch, temperature, and pain

efferent neuronal systems

the part of the nervous system that carries signals from the central nervous system (brain and spinal cord) to muscles and glands, controlling movement and bodily functions; these neurons are responsible for actions like muscle contraction and hormone release

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses by undergoing mechanosensory transduction

ependymal cells

line the ventricles of the brain and have cilia that promote circulation of the cerebrospinal fluid that fills these compartments

astrocytes

facilitate information transfer, regulate extracellular ion concentrations, promote blood flow to neurons, help form the blood-brain barrier, act as stem cells to replenish certain neurons, metabolize neurotransmitters, and modulate synaptic effectiveness

oligodendrocytes

myelinate axons in the CNS, which greatly increases the conduction speed of action potentials

microgiia

immune cells in the CNS that protect against pathogens

schwann cells

myelinate axons in the PNS

radial glia

form tracks along which newly formed neurons migrate from the neuron tube, the structure that gives rise to the CNS

forebrain

largest part of the brain, located at the front that includes the cerebrum, thalamus, hypothalamus, and other structures; responsible for higher functions such as thinking, emotion, learning, and memory, as well as regulating autonomic functions

midbrain

part of the brainstem that connects the forebrain to the hindbrain; plays a key role in processing sensory information (especially visual and auditory), controlling motor movements (particularly eye movements), and regulating arousal and alertness

hindbrain

lower part of the brainstem, consisting of the medulla oblongata, pons, and cerebellum; responsible for vital functions such as breathing, heart rate, and motor control, as well as coordination and balance

cerebral cortex

outer region of the cerebrum, containing sheets of nerve cells; gray matter of the brain; vital for perception, voluntary movement, and learning

acetylcholine

neurotransmitter that plays a key role in muscle contraction; released from motor neurons at the neuromuscular junction (synapse between motor neuron and muscle fiber) and binds to receptors on muscle cells, triggering the muscle to contract