Nervous Coordination: Nervous System and Sense Organs Flashcards
Basic Plan of the Nervous System
- receive information from external and internal environments
- encode information
- transmit and process for appropriate action
- functional units of nervous systems
- May assume many sizes depending on its function and location
- Has one or more dendrites and a single axon
- nerve cell’s receptive apparatus
neurons
cause a signal to be generated and propagated
excitatory
making signal generation and propagation less likely
inhibitory
Classifications of Neurons
- Afferent (sensory)
- Efferent (motor)
- Interneurons (neither sensory nor motor)
surrounded by a single Schwann cell
unmyelinated neuron
Cell bodies are located either in the __ __ __ or in __
- central nervous system
- ganglia
vertebrate nerves are often enclosed by concentric rings of __
myelin
In the peripheral nervous system, myelin is produced by
Schwann cells
In the central nervous system, myelin is produced by
oligodendrocytes
- an electrochemical message of neurons
- alike in all neurons in all animals
- “All-or-none” phenomenon
- nerve fibers vary its signal by changing the frequency of signal conduction
- the higher the frequency (or rate) of conduction, the greater is the level of excitation
- nerve signal or
- action potential
Resting Membrane Potential:
inside axon
Large impermeable anions: high
Potassium: high
Sodium: low
Chlorine: low
Resting Membrane Potential:
outside axon
Large impermeable anions: low
Potassium: low
Sodium: high
Chlorine: high
Inside axon = __mV
-70
Outside axon = __mV
0
When at rest, the membrane of a neuron is selectively permeable to __
K+
The permeability to __ is nearly zero because __ __ are closed in a resting membrane
- Na+
- Na+ channels
__ ions tend to diffuse __ through the membrane, following the gradient of potassium concentration.
- Potassium
- outward
Because large anions cannot pass through the membrane, __ __ potassium ions are drawn back into the cell
positively charged
A resting cell membrane has a very low permeability to Na+ but due to the __ __ __ and __ __, some Na+ leaks through it into the cell, even in the resting condition
- high concentration gradient
- electrical attraction
decayed resting membrane potential of the fiber is prevented by __ __
sodium pumps
In CNS, __ help to maintain the correct balance of ions surrounding neurons by storing excess potassium produced during neuronal activity
astrocytes
- rapidly moving change in electrical membrane potential
- very rapid and brief depolarization of the membrane of the nerve fiber
- In a millisecond, the membrane potential changes from rest so that the outside becomes negative compared with the inside
action potential
once started the action potential moves along the nerve fiber automatically and unchanged in intensity, much like the burning of a fuse
Self-propagating
______ open suddenly for less than a millisecond, permitting Na+ to diffuse into the axon from the outside moving down the concentration gradient for Na and depolarizes the membrane.
Voltage-gated Na+ channels
The _______ is highly correlated with __ of the axon
- speed of conduction
- diameter
__ __ conduct slowly because internal resistance to current flow is high
Small axons
__ __ for most invertebrates for quick response such as in locomotion to capture prey or to avoid capture
Large axons
High conduction velocities in invertebrates is because of the
cooperative relationship between axons and investing layers of myelin
- action potential leaps from node to node, bypassing the insulated portions of the fiber
- Faster than continuous conduction
saltatory conduction
junction between nerves
synapses
Two (2) kinds of synapses
- Electrical synapses
- Chemical synapses
- mechanical link between two neurons that allows for the conduction of electricity
- show no time lag and consequently are important for escape reactions
electrical synapse
electrical synapse is demonstrated in both
- invertebrate
- vertebrate
- Much complex than electrical impulses
- contain packets or vesicles of specialized chemicals called neurotransmitters
chemical synapse
specialized chemicals in chemical synapse
neurotransmitters
Neurons bringing action potentials toward chemical synapses
presynaptic neurons
Neurons carrying action potentials away
postsynaptic neurons
appendages that are designed to receive communications from other cells
Dendrites
ends of the neuron that are associated with the signaling of the neuronal impulses
synaptic knobs
key organelles involved in synaptic functions such as uptake, storage and stimulus-dependent release of neurotransmitter
Synaptic vesicles
membrane of a neuron that releases neurotransmitter into the synaptic cleft between nerve cells
presynaptic membrane
membrane that receives a signal (binds neurotransmitter) from the presynaptic cell and responds via depolarisation or hyperpolarisation
postsynaptic membrane
The space between two neurons across which the impulse is transmitted by a neurotransmitter
synaptic cleft
transmit the actions of bound neurotransmitters, thus enabling cell-to-cell communication in the nervous system
Neurotransmitter receptors
Evolution of Nervous System in Invertebrates
Development of Centralized Nervous Systems
Evolution of Nervous System:
Hydra
nerve network
Evolution of Nervous System:
Planaria
- anterior ganglia
- nerve trunks
Evolution of Nervous System:
Earthworm
- bilateral brain
- segmental ganglia
Evolution of Nervous System:
Grasshopper
segmental ganglia
- small organ of balance and orientation in some aquatic invertebrates
- consisting of a sensory vesicle or cell containing statoliths
statocysts
- simple photo-receptors (light-detecting organs)
- consist of a single lens and several sensory cells
- used to detect movement
Ocelli
- proximal segments of peripheral nerves
- emerging from the foramina of the spine with interchanging and intertwining nerves from different spinal levels that then form individual nerves more distally
nerve plexuses
simplest nervous system showing differentiation into a peripheral nervous system and a central nervous system which coordinates everything
Planaria:
- two anterior ganglia
- two main nerve trunks
The basic plan of molluscan nervous systems is a series of __ __ of __ __
- three pairs
- well-defined ganglia
animals with ganglia burgeoned into textured nervous centers of
great complexity (in octopuses, contain more than 160 million cells)
cephalopods
ganglia of cephalopods
- highly developed sense organs
- capable of learning
arthropods elaborates __ __ and learning have been documented in hymenopteran insects (bees, wasps, and ants) despite having a small brain
social behavior
- pair of easily discernible neuropils comprising thousands of densely packed parallel neurons running on either side of the central complex from back to front and downward through the protocerebrum
mushroom bodies
basic plan of the vertebrate NS which terminates anteriorly in a large mass or brain
Hollow dorsal nerve cord
a concept that implies an increase in brain or neocortex size relative to body size, size of lower brain areas, and/or evolutionary time
Encephalization
__ and __ __ compose the
CNS
- brain
- spinal cord
During early embryonic development, the spinal cord and brain begin as an __ __ __, which by folding and enlarging becomes a long, hollow neural tube
ectodermal neural groove
- special type of neural circuit that begins with a sensory neuron at a receptor and ends with a motor neuron at an effector
- Refers to many neurons that work in group
- Contains at least two neurons
reflex arc
Typical Parts of the Reflex Arc
- receptor
- afferent (sensory)
- central nervous system
- efferent (motor)
- effector
- home to neural cell bodies, axon terminals, and dendrites, as well as all nerve synapses
- abundant in the cerebellum, cerebrum, and brain stem
- forms a butterfly-shaped portion of the central spinal cord
Gray matter
- extends downward from the base of your brain
- made up of nerve cells and groups of nerves that carry messages between your brain and the rest of your body
spinal cord
- emerges from the dorsal root of the spinal nerves
- carry sensory messages from various receptors at the periphery towards the central nervous system for a response
dorsal root ganglion (DRG)
- space between two neurons where the message transfers between them
- there is only one point where the message transfers between neurons
monosynaptic synapse
nerve cells that are activated by sensory input from the environment
sensory neurons
transmit impulses from the spinal cord to skeletal and smooth muscles, and so directly control all of our muscle movements
motor neuron
group of muscles at the front of your thigh
quadriceps muscle
in blood vessel walls, they detect blood pressure and convert mechanical stretch into action potentials to be sent to the central nervous system
Stretch receptors
largest sesamoid bone in the human body and is located anterior to knee joint
patella
attaches the bottom of the kneecap (patella) to the top of the shinbone (tibia)
patellar tendon
- connect spinal motor and sensory neurons
- can also communicate with each other, forming circuits of various complexity
interneurons
- response to a stimulus acting over a reflex arc
- Involuntary; breathing, heartbeat, diameter of blood vessels, sweat secretion
- Some are innate; others are acquired through learning
reflex act
Center of the nervous system in all vertebrate animals and most invertebrate animals
brain
called the brain “great raveled knot”
Sir Charles Sherrington
what did Sir Charles Sherrington call the brain
“great raveled knot”
animal with the largest brain
sperm whale
Three (3) principal divisions of the brain of early vertebrates
- prosencephalon (forebrain)
- mesencephalon (midbrain)
- rhombencephalon (hindbrain)
- comprise more than 99% of the neurons in humans
- major neuron type found in the CNS and the efferent division of the PNS
Multipolar neurons
prosencephalon
smell
mesencephalon
vision
rhombencephalon
hearing and balance
- compact section of a nerve cell that contains the nucleus and the cytoplasm
- located either in CNS or in ganglia
cell body
Myelin sheath is made up of what substances
protein and fatty substances
Ratio of glial cells to nerves cells
3:1
axons with myelin sheath conducts __
faster
high conducting velocity
endotherms
conducting velocity fluctuates
ectotherms
Two pairs of nerve roots extend from each segment of the spinal cord
- ventral roots
- dorsal roots
anterior roots
ventral roots
posterior roots
dorsal roots
allow motor neurons to exit the spinal cord
ventral roots (anterior roots)
allow sensory neurons to enter the spinal cord
dorsal roots (posterior roots)
protect the central nervous system (CNS)
- meninges
- Cerebrospinal fluid (CSF)
Polysynaptic reflex use what neurons
interneurons
utilizes interneurons which pass signals between the sensory and motor neurons, ultimately creating multiple synaptic connections
polysynaptic reflex
Amount of neurons in the brain
86 billion
- where the most complex brains are found
- largest and most complex one among invertebrates
- squids (Theutidae)
- octopods (Octopoda)
Looks like an extension of spinal cord
rhombencephalon (hindbrain)
Three parts of the hindbrain
- medulla oblongata
- cerebellum
- pons
- bottom-most part of your brain
- where the brain and spinal cord connect, making it a key conduit for nerve signals to and from the body
- helps control vital processes like heartbeat, breathing and blood pressure
medulla oblongata
- controls numerous vital and largely subconscious activities such as heartbeat, respiration, vascular tone, gastric secretions, and swallowing
- bottom, stalklike portion of your brain
brain stem
What does the brain stem control
subconscious activities
Ex. of subconscious activities the brain stem control
- heartbeat
- respiration
- gastric secretions
- swallowing
- handles unconscious processes and jobs, such as your sleep-wake cycle and breathing
- contains several junction points for nerves that control muscles
- carry information from senses in your head and face
- thick bundle of fibers that carry impulses from one side of
the cerebellum to the other
pons
What do pons control
unconscious processes and jobs
Ex. of unconscious processes and jobs
- sleep-wake cycle
- breathing
Pons connect what
medulla and cerebellum to other brain regions
important for making postural adjustments in order to maintain balance
cerebellum
What does the cerebellum control
- equilibrium
- posture
- movement
have most complex cerebellum
primates (esp. humans)
have weakly developed cerebellum
- amphibians
- non-avian reptiles
have well developed cerebellum
agile bony fishes
- home to sensory processing, endocrine structures, and higher reasoning
- largest region of your brain
prosencephalon (forebrain)
Two main divisions of the forebrain
- Diencephalon
- Telencephalon
Diencephalon
- thalamus
- hypothalamus
Telencephalon
cerebrum
- major relay station
- analyzes and passes sensory information to higher brain centers
thalamus
- acts as body’s smart control coordinating center
- keep the body in a stable state called homeostasis
- directly influence the autonomic nervous system
- manage hormones
hypothalamus
what does the hypothalamus regulate
- reproductive function
- sexual and emotional behavior
Four lobes of the brain
- Frontal lobe
- Parietal lobe
- Occipital lobe
- Temporal lobe
- largest lobes in the human brain
- important for voluntary movement, expressive language and for managing higher level executive functions
frontal lobes
Frontal lobe function
- voluntary movement
- expressive language
- managing higher level executive functions
- home to the brain’s primary somatic sensory cortex
- interprets input from other areas of the body
- responsible for integrating sensory information, including touch, temperature, pressure and pain
parietal lobe
Parietal lobe function
- integrating sensory information
(touch, temperature, pressure, pain)
visual processing area of the brain
occipital lobe
Occipital lobe function
- visual perception (color, form and motion)
- memory formation
- most commonly associated with processing auditory information and with the encoding of memory
temporal lobe
Temporal lobe function
- processing auditory information
- encoding of memory
- thick bundle of nerve fibers that connects the two hemispheres in your brain
- ensures both sides of the brain can communicate and send signals to each other
corpus callosum
- where the optic nerves cross
- primary importance to the visual pathway
optic chiasm
- Largest part of the brain
- control muscle functions and also control speech, thought, emotions, reading, writing, and learning
cerebrum
Two divisions of the anterior portion of the forebrain
- Paleocortex
- Neocortex
Paleocortex
limbic system
Neocortex
cerebral cortex
“nose brain”
rhinencephalon
- mediates several species-specific behaviors that relate to fulfilling needs such as feeding and sex
- an old cortical area in which olfactory fibers are projected
paleocortex
site of spatial learning and memory
hippocampus
- comprises the largest part of the cerebral cortex and makes up approximately half the volume of the human brain
- commands higher functions, such as sensory perception, emotion, and cognition
neocortex
- large “silent” regions concerned with integrative functions that are not directly connected to sense organs or muscles
- occupy about 80% of the cortex
association areas
- primarily responsible for speech and abstract thinking
- controls the right side of the body
left brain
- responsible for image processing, spatial thinking
- controls movement in the left side of the body
right brain
refers to parts of the nervous system outside the brain and spinal cord
peripheral nervous system
- associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation
- sort of relay station for auditory and visual information
midbrain
Midbrain carries signals from __ to __ center
- lower brain
- higher brain
Two functional divisions of the peripheral nervous system (PNS)
- Sensory (afferent division)
- Motor (efferent division)
Two components in efferent division
- Somatic nervous system
- Autonomic nervous system
carry information from sensory receptors found all over the body towards the central nervous system
Afferent neurons
carry motor information away from the central nervous system to the muscles and glands of the body in order to initiate an action
Efferent neurons
component of the peripheral nervous system associated with the voluntary control of the body movements via the use of skeletal muscles
somatic nervous system
component of the peripheral nervous system that regulates involuntary physiologic processes including heart rate, blood pressure, respiration, digestion, and sexual arousal
autonomic nervous system
12 Cranial Nerves
1 - Olfactory
2 - Optic
3 - Oculomotor
4 - Trochlear
5 - Trigeminal
6 - Abducens
7 - Facial
8 - Vestibulocochlear
9 - Glossopharyngeal
10 - Vagus
11 - Spinal Accessory
12 - Hypoglossal
Cranial Nerves mnemonics
Ooo To Touch And Feel Very Good Velvet Such Heaven
Type of nerves of the 12 cranial nerves
1 - sensory
2 - sensory
3 - motor
4 - motor
5 - both
6 - motor
7 - both
8 - sensory
9 - both
10 - both
11 - motor
12 - motor
Cranial Nerve Types mnemonics
Some say marry money but my brother says big brains matter more
mixed nerves that interact directly with the spinal cord to modulate motor and sensory information from the body’s periphery
spinal nerve
Two motor neurons of the autonomic NS
- Preganglionic autonomic neurons
- Postganglionic autonomic neurons
Subdivisions of the autonomic nervous system
- Parasympathetic NS
- Sympathetic NS
- network of nerves that relaxes your body after periods of stress or danger
- helps run life-sustaining processes, like digestion, during times when you feel safe and relaxed
parasympathetic nervous system
- network of nerves that helps your body activate its “fight-or-flight” response
- system’s activity increases when you’re stressed, in danger or physically active.
sympathetic nervous system
- network of vessels that clear waste from the central nervous system, mostly during sleep
- promote efficient elimination of soluble proteins and metabolites from the central nervous system
glymphatic nervous system
- have specialized sensory receptors designed for detecting environmental status and change
- biological transducers; specific for one kind of stimulus
- provide senses of sight, hearing, smell, taste, and touch, respectively, to aid the survival, development, learning, and adaptation of humans and other animals
Sense organs
Sense organs
- eyes
- ears
- nose
- tongue
- skin
states that an individual’s mind cannot access objects in the natural environment except through the nerves
Law of Specific Nerve Energies
first described the Law of Specific Nerve Energies
Johannes Muller in 1830s
- near the external surface
- keep an animal informed about its external environment
exteroceptors
- internal parts of the body
- receive stimuli from internal organs
interceptors
- in muscles, tendons, joints
- sensitive to changes in tension of muscles and provide an organism with a sense of body position
proprioceptors
Form of energy to which the receptors respond
- chemical
- mechanical
- light
- thermal
oldest and most universal sense in the animal kingdom
chemoreception
in unicellular forms, locate food and adequately oxygenated water and to avoid harmful substances
Contact chemical receptors
orientation behavior; toward or away from a chemical source
Chemotaxis
in metazoans; often developed into a remarkable degree of sensitivity
Distance chemical receptors
guides feeding behavior, location and selection of sexual mates, territorial and trail marking, and alarm reactions of numerous animals
Distance chemoreception
sensory hairs in which insect chemoreceptors are located
Sensilla
- present on the mouthparts, legs, wing margins, and ovipositor in females.
- have a single pore at the tip and recognize four classes of compounds: sugar (attractive), bitter (repelling), salts, and water
Taste sensilla
Four classes of compounds the taste sensilla recognize
- sugar (attractive)
- bitter (repelling)
- salts
- water
- located on the head on two pairs of olfactory organs: the antennae and the maxillary palps
- pores on the cuticular walls allow odorant and pheromone molecules from the environment to contact the olfactory receptor neurons
Olfactory sensilla
- substances which are secreted to the outside by an individual and received by a second individual of the same species
- affect the physiology or behavior of another individual of the same species
Pheromones
Where does the taste receptor in mammals occur
tongue
Taste sensation categories
- sweet
- salty
- acid
- bitter
- umami
taste buds lifespan
5 - 10 days in mammals
- most highly developed in mammals
- endings are located in a special epithelium covered by a thin film of mucus
- positioned deep in the nasal cavity
olfaction
flavor of foods depends on what?
odors reaching the olfactory epithelium during throat passage
additional olfactory organ in many terrestrial vertebrates which responds to pheromones
vomeronasal organ
Other term for vomeronasal organ
Jacobson’s organ
- sensitive to quantitative forces such as touch, pressure, stretching, sound, vibration, and gravity
- respond to motion
mechanoreceptors
found in receptors of invertebrates (esp. insects) that are sensitive to both touch and vibration
Tactile hairs
in vertebrates; concentrated in areas especially important exploring and interpreting the environment
Superficial touch receptors
register deep touch and pressure in mammalian skin
Pacinian corpuscles
unspecialized nerve fiber endings that respond to a variety of stimuli signaling possible or real damage to tissues
Pain receptors
Pain receptors also respond to __ __ of a tissue and __ __
- mechanical movement
- temperature changes
Pain fibers respond to small peptides, such as substance P and bradykinins, which are released by injured cells
Slow pain
more direct response of the nerve endings to mechanical or thermal stimuli
Fast pain
- sensory system found in fishes and aquatic amphibians
- measure the relative movements between their body and the surrounding water at each of up to several thousand sensory organs, the neuromasts
lateral-line system
- receptor cells located on the body surface in aquatic amphibians and canals
- running beneath the epidermis of fishes
neuromasts
specialized receptor for detecting sound waves in the surrounding environment
ear
part of the ear that contains organs of the senses of hearing and equilibrium
labyrinth or inner ear
Subdivisions of the labyrinth
- vestibular labyrinth
- cochlear labyrinth
What does the vestibular labyrinth contain
- two sacs (utricle and saccule)
- three semicircular canals
Two sacs in the vestibular labyrinth
- utricle
- saccule
fluid-filled membrane that contains the receptors for hearing
cochlear labyrinth
specialized sense organs for monitoring gravity and low-frequency vibrations in invertebrates
Statocysts
light-sensitive receptors
Photoreceptors
Photoreceptors
- simple light-sensitive cells (invertebrates)
- developed camera-type eye (vertebrates & cephalopods)
Two different principles in more highly organized eyes
- Single-lens
- Multifaceted
eyes of cephalopod mollusks and vertebrates
single-lens
eyes in arthropods
multifaceted
Eyes that are built like a camera:
front
- light-tight chamber and
- lens system
Eyes that are built like a camera:
back
light-sensitive surface
(the retina)
- responsible for your sense of sight
- part of the eye responsible for converting the light that enters your eye into electrical signals that can be decoded by the vision-processing center of the brain
Rods and cones
responsible for color vision
cones
light-sensitive pigments in both rods and cones
Rhodopsins
Rhodopsin molecule consists of
- opsin
- retinal
large protein in rhodopsin
opsin
small carotenoid molecule and a derivative of vitamin A in rhodopsins
retinal
contains much rhodopsin and is very sensitive to weak light
dark-adapted eye
- most of the rhodopsin is split into retinal and opsin
- takes approximately half an hour to accommodate to darkness
light-adapted eye
Cones require __ to __ times more light for stimulation than rods
50 - 100
have pure rod retinas
nocturnal animals
- have only cones
- virtually blind at night
diurnal forms
Speculated that humans see color by relative excitation of three kinds of photoreceptors
Thomas Young
Three types of cones in humans
- blue
- green
- red
- system that determines the movements of the gastrointestinal tract
- regulates gastric acid secretion, changes in local blood flow and the gut hormones release
- interacts with the immune system in the gut
enteric nervous system
What are the spinal nerves
- cervical nerves (C1-C8)
- thoracic nerves (T1-T12)
- lumbar nerves (L1-L5)
- sacral nerves (S1-S5)
- coccygeal nerves (CO1)
