Nervous System Flashcards
Response to stimuli
Responsiveness or Iriritability
It consists of neurons that carry information into and out of the Central Nervous System
Peripheral Nervous System
It consists of the brain and, in vertebrates, the spinal cord
Central Nervous System
What is the main type of tissue comprising the vertebrate nervous system
Nervous Tissue
It comprises 10% of the total number of cells in the nervous system
Neurons
Special cells that are associated with neurons. They come in many different types, and they perform many different functions
Neuroglia or glial cells
Function of Neuroglia cells
- Support for the brain (physically)
- Assist in nervous system repair and
maintenance (prune neurons) - Assist in the development of the nervous
system - Provide metabolic functions for neurons
(attach them to blood vessels)
Types of Neuroglia
- Microglia
- Astrocytes
- Oligodendrocytes
- Schwann cells
- Ependymal cells
- Satellite cells
Are small, ovoid phagocytes that monitor the health of neurons.
Microglia
Are the most abundant; they are highly branched. They cling to neurons and their synaptic endings, and cover capillaries
Astrocytes
Are glial cells that have processes that wrap
around the nerve fibers of the central
nervous system.
Oligodendrocytes
Wraps around the nerve fibers of the peripheral nervous system.
Schwann cells
Both of them produce or form myelin sheath
Oligodendrocytes and Schwann cells
A type of glial cell that lines the central cavities of the brain and spinal cord filled with cerebrospinal fluid (CSF)
Ependymal cells
Are glial cells that surround and support neuron cell bodies in the peripheral nervous system ganglia
Satellite cells
- the basic structural and functional
unit of the nervous system - electrically excitable
- unusually long compared to other
cell types; even considered
longest cells in some cases
Neuron or nerve cell
Function of Neuron or nerve cells
Transmission of nerve impulse
Parts of a myelinated neuron
- Cell body / Soma / Perikaryon / Cyton
- Dendrites
- Axon
- Node of Ranvier
Central part of the neuron and contains the nucleus and others
Cell body
They carry impulses towards the cell body.
- short, branched, processes extending from cell body
Dendrites
Carries impulses away from the cell body.
- long process extending from the cell body
Axon
Gap in the myelin sheath between the adjacent Schwann cells or Oligodendrocytes
Node of Ranvier
Structures of Neurons
- Anaxonic neuron
- Bipolar neuron
- Unipolar neuron
- Multipolar neuron
Percentage of neurons that are multipolar
More than 99%
Types of Neurons according to function
- Sensory Neurons or Afferent Neurons
- Motor or Efferent Neurons
- Interneurons or Associative Neurons or Intermediate Neurons
Transmit sensory information from receptors to the central nervous system.
Sensory Neurons or Afferent Neurons
Convey commands from the central nervous system to muscles or glands to initiate actions.
Motor or Efferent Neurons
Act as connectors within the central nervous system, facilitating communication between sensory and motor neurons and playing a role in information processing and integration.
Interneurons or Associative Neurons or Intermediate Neurons
Phases of Action Potential
- Resting (polarized) phase
- Depolarizing phase
- Repolarizing phase
- Hyperpolarizing phase
Are brain chemicals that
communicate information throughout our
brain and body. They relay signals between
nerve cells and between nerve cells and
effectors.
Neurotransmitters
Excitatory Neurotransmitters
- Dopamine
- Glutamate
- Acetylcholine
- Norepinephrine
- Epinephrine
Inhibitory Neurotransmitters
- Dopamine
- Serotinin
- Gamma-Amino Butyric Acid
It is formed when cells of the nervous system are grouped together
Nerve Tissue
Group of cell bodies outside CNS
Ganglion
Group of neurons within CNS
Nucleus
Group of nerve fibers outside CNS
Nerve
Group of nerve fibers within CNS
Tract
Refers any physical or chemical change capable of exciting an organism or its parts
Stimulus
A cell or organ having a special sensitivity to some particular kind/kinds of stimuli
Receptor
Cell, Tissue, or organ which react to stimuli
Effector
Components of Nervous System
Brain and Spinal Cord
General Function of Nervous System
Serves as information processing center
and central command post
It is protected by the cranium
Brain
It is protected by vertebral column
Spinal cord
The divisions of the Brain
- Forebrain
- Midbrain
- Hindbrain
The largest part of the brain. Controls the somatosensory, motor, language, cognitive thought, memory, emotions, hearing and vision
Cerebrum
A wide thick nerve tract connecting the cerebral hemispheres.
Corpus Callosum
Function of Frontal Lobe
- Motor control
- Problem solving
- Speech production
Function of Temporal Lobe
- Auditory processing
- Language comprehension
- Memory / Information retrieval
Function of Parietal Lobe
- Touch perception
- Body orientation and sensory discrimination
Function of Occipital Lobe
- Sight
- Visual reception and Visual interpretation
Function of Cerebellum
- Balance and coordination
Function of Brainstem
Involuntary responses
Acts as relay station for impulses travelling to and from spinal cord, brainstem, cerebellum and cerebrum
Thalamus
- Monitors water concentration, hormone
concentrations and body temperature - associated withfeelings of rage,
aggression, hunger and thirst. - plays an important role as an intermediary
between the nervous system and the
endocrine system
Hypothalamus
- involved in the processing of emotions
such as fear, anger and pleasure - determines what memories are stored
and where the memories are stored in
the brain
Amygdala
- Formation, storage and organization of
new autobiographical and fact memories - Emotionalresponses
- Navigation
- Spatial orientation
Hippocampus
It is composed of parts of the
forebrain, including the hypothalamus ,
amygdala and hippocampus.
Limbic System
The small region of the brain that connects the forebrain with the hindbrain. It allows continuity of relay of information from the forebrain to the hindbrain and vise versa
Midbrain
Main parts/ Function of midbrain
- Superior colliculi (vision)
- Inferior colliculi (hearing)
- Tegmentum (consciousness)
- Cerebral peduncle (motor function)
- Red nucleus (motorfunction)
- Substantia nigra (motor function)
The most posterior region of the brain
Hindbrain
The second largest part of the brain
Cerebellum
- helps control posture and balance
- coordinates voluntary movements
Cerebellum
- serves as a bridge between the cerebellar hemispheres
- also involved in production of chemicals the body needs for sleep
Pons
- controls breathing, heart rate, and a variety of reflexes
- relay of nerve signals between the brain and spinal cord
- coordination of body movements
Medulla Oblongata
Acts as regulatory system for sleep, waking, and alertness
Reticular Formation
What is the brainstem composed of
Midbrain, Pons, and Medulla Oblongata
It contains centers that regulate several functions that are vital for survival, which include blood pressure, heartbeat, respiration, digestion, and certain reflex actions such as swallowing and vomiting.
Brainstem
Is an elongate tube that extends from the base of the brain to the lumbar region of the vertebral column. It is protected by the vertebral column, meninges and CSF.
Spinal Cord
Functions of Spinal Cord
- Connects the brain with PNS
- Controls responses that do not involve the brain
Arises from the surface of the Brain
Cranial Nerves
Arises from the Spinal Cord
Spiral Nerve
How many pairs of nerves does the Cranial Nerve have
12 pairs
How many pairs of nerves does the Spinal Nerve have
31 pairs
What is the largest cranial nerve
Trigeminal Nerve
What is the longest nerve
Vagus
What is the shortest nerve
Olfactory
Nerves in the Spinal Cord
- Cervical Nerves
- Thoracic Nerves
- Lumbar Nerves
- Sacral Nerves
- Coccyligeal Nerves
How many pairs of nerves does the Cervical nerve have
8 pairs
How many pairs of nerves does the Thoracic nerve have
12 pairs
How many pairs of nerves does the Lumbar nerve have
5 pairs
How many pairs of nerves does the Sacral nerve have
5 pairs
How many pairs of nerves does the Coccygeal nerve have
1 pair
Referred to as “the system that never sleeps” and is composed of nerves which has opposite effects on various parts of the body involved the involuntary actions
Autonomic Nervous System
It controls voluntary responses that control skeletal muscle contraction
Somatic Nervous System
- controls the exchange of information
between receptors, CNS and the
skeletal muscle - controls all voluntary responses
Functions of Somatic Nervous System
The most common cause of dementia in elderly
Alzheimer’s disease
A serious and often debilitating mental illness
Schizophrenia
One of the most common mental disorders
Depression
Are cells, tissues or organs
having a special sensitivity to some
particular stimulus
Receptors
2 ways to classify receptors
- Based on location or source
- Type of stimulus it can detect
A receptor sensitive to stimuli from external environment
Exteroreceptors
A receptor sensitive to stimuli from internal environment
Interoceptors
A receptor sensitive to both external and internal stimuli and are responsible for relaying information about our body’s
spatial position to the brain (muscle length and tension, limb position)
Proprioceptors
A receptor that detect deformation of the receptors or adjacent cells; provide sensations of touch, pressure, vibration, proprioception, hearing, equilibrium, blood pressure, and stretching of internal organs
Mechanoreceptors
A receptor that detect change in temperature
Thermoreceptors
A receptor that can respond to stimuli resulting from physical or chemical damage to tissue
Nociceptors
A receptor that detects light that strikes the retina of the eye
Photoreceptors
A receptor that detects chemicals in mouth (taste), nose (smell), and body fluids
Chemoreceptors
A receptor that can sense the osmotic pressure of body fluids
Osmoreceptors
A receptor that is sensitive to pressure changes and are considered mechanoreceptors
Baroreceptors
Are sites of sensory receptors which collect information from the external environment and relay it to the NS then to the effectors.
Sense Organs
A receptor located within the skin or underlying tissues
Cutaneous (skin) receptors
Dense collections of myelinated fibers
White matter
Mostly soma and unmyelinated fibers
Gray matter
Sensitive to heat, cold or pain
(thermoreceptors, nociceptors and mechanoreceptors).
Free nerve endings
Respond to
touch and low-frequency vibration
Meissner’s corpuscles (tactile corpuscles)
Detect stretch, deformation with joints,
and warmth (sensitive to pressure).
Ruffini Endings
Very sensitive mechanoreceptor for
touch that is located at the base of the hair
Root hair plexus
The largest skin receptor, very quick to
adapt to skin displacement (sensitive
to pressure).
Pacinian Corpuscle
Mechanoreceptors, sensitive to cold,
more superficially located than Ruffini endings
Krause end bulbs
Located superficially in the dermis,react slowly to pressure (sustained pressure)
Merkel’s disks
Total or partial loss of feeling
Anesthesia
Sensation of pricking and tingling followed by numbnesss.
Paresthesia
An abnormal or pathological increase in sensitivity to
sensory stimuli, as of the skin to touch
Hyperesthesia
A deadening or absence of the sense of pain without loss of
consciousness.
Analgesia
Exaggerated sense of pain
Hyperalgesia
3 distinct layer of tissue that composes the Eye
- Fibrous coat
- Vascular coat
- Retina and a lens
Thick fibrous
connective tissue that forms the
outer layer of the eyeball
Fibrous Coat
A part of the vascular coat. It is the white part of the eye
Sclera
A part of the vascular coat. The transparent front part; covered by a thin conjunctiva
Cornea
The highly vascular, opaque and incomplete layer between the retina and the sclera
Fibrous Coat
A part of the Fibrous coat. The
pigmented part at the back of the
eyeball that is rich in blood vessels
Choroid
A part of the vascular coat. The layer innert o the junction of sclera and cornea; has muscles that control the size of
the eyeball
Ciliary Body
A part of the vascular coat. It is the colored part of the eye; has a pupil and
muscles (radial and circular) that regulate the
diameter of the pupil
Iris
It is the opening
(circular black area) in the center of the iris. Its diameter changes in response to light.
Pupil
Are biconvex, circular, transparent
structure behind the pupil an elastic structure; its shape can be varied to adjust to objects at varying distances.
Lens
The lens is held in place with the help of what ligament
Suspensory ligament
Function of the Lens
Serves to focus the light on the retina
What are the layers of the Retina
- Photoreceptor layer : rods & cones
- Intermediate layer : bipolar neurons
- Internal surface : ganglia
It is used for peripheral vision where the image produced is not sharp and in shades of gray
Rods
It is used for photopic vision, capable of color vision and are responsible for high spatial acuity
Cones
-the point on the retina where the optic
nerve leaves the eye
-no rod or cone (so no image is formed)
Blind spot (optic disc)
It contains the densest concentration of cones and is responsible for sharp central vision like what is needed when reading or doing anything that requires visual detail
Fovea centralis
It is a condition where the cornea or lens is
irregularly shaped so that it prevents light from focusing properly on the retina, thus
causing blurred vision. It is corrected with cylindrical lens.
Astigmatism
It is a condition where the shape of the lens changes causing difficulty in focusing. It is corrected with bifocal lenses or with progressive lens
Presybopia
It is a group of eye diseases that can
cause vision loss and blindness by damaging the optic nerve. The most common cause is high intraocular pressure
Glaucoma
It is a vision condition in which the eyes make repetitive, uncontrolled movements.
Nystagmus
It involves perception of chemicals in air by chemreceptors in the epithilium lining in the nasal cavity. The sense of smell is called?
Olfaction
Refers to the inability to detect odors
Anosmia
Refers to the decreased ability to detect odors
Hyposmia
Very strong sense of smell
Hyperosmia
It refers to the distorted identification of smell
Dysosmia
It refers to the altered perception of smell in the presence of an odor, usually unpleasant
Parosmia
Perception of smell without an odor present
Phantosmia
It refers to the inability to classify or contrast odors, although able to detect odors
Agnosia
Are chemicals released by animals that affect the behavior or physiology or animals of the same species
Pheromones
It is the sensory function of the tongue
Gustation
It perceives temperature and along with the rest of the mouth, it helps determine the food’s texture, oiliness, chewiness, viscosity and density and even pain like what is felt when food is hot
Tongue
It refers to the inability to taste
Ageusia
It refers to the decreased ability to taste
Hypogeusia
It refers to the distorted ability to taste
Dysgeusia
A bad taste in the moouth
Parageusia
The weakest among the five senses
Taste
Regions of the ear
- Outer ear
- Middle ear
- Inner ear
The earflap or auricle. Located in the outer ear
Pinna
Narrow tube running from the pinna to eardrum. Located in the outer ear
Auditory canal / tube / meatus
- Consists basically of very thin
sheet of skin and connective
tissue - Ultimately converts and
amplifies vibration in air to vibration in fluid - Located in the middle ear
Eardrum or Tympanic membrane
- Malleus (hammer)
- Incus (anvil)
- Stapes (stirrup)
- Located in the middle ear
Ossicles or ear bones
What connects the middle er to the pharynx
Eustachian tube
- A small fluid-filled, snail-shaped channel through the temporal bone
- Contains the receptors for transduction of the mechanical wave into an electrical signal
- Located in the inner ear
Cochlea
- Half-circular, fluid-filled tubes in
the vestibular labyrinth - Located in the inner ear
Semicircular canals
The fluid within the space (scala tympani and scala vestibuli) separating the membranous and bony labyrinths of the ear
Perilymph
The fluid contained in the
membranous labyrinth of the inner
ear (cochlear duct)
Endolymph
The receptor organ for hearing
located in the mammalian cochlea.
Organ of Corti
Specialized sense organs for monitoring gravity and low-frequency vibrations present from cnidarians to arthropods
Stratocysts
When sensory receptors reduce their sensitivity to a continuous, unchanging stimuli
Sensory Adaption
