Bio - Ch 35 Nervous System
Impulses
The messages carried by the nervous system are electrical signals called impulses
What is the difference between grey matter and white matter
The outer layer of the cerebrum is called the cerebral cortex and consists of grey matter which consists mainly of densely packed nerve cell bodies. The inner layer of the cerebrum consists of white matter, which is made up of bundles of axons with myelin sheaths
What happens when the nerve senses that the core temperature has dropped below 35 C?
The hypothalamus produces chemical that signals cells throughout the body to speed up their activities. Heat is produced by this increase in cellular activity
How does a reflex arc work?
The peripheral nervous system transmits impulses from sense organs to the CNS and back to muscles or glands.
Neuron
The cells that transmit impulses
What happens when the nerve system senses that the core temperature gone to high above 35 C?
The hypothalamus slows down cellular activities, minimizing the production of heat
Threshold
The level of stimulation required to trigger a neural impulse
What do the eleven organ systems do as a whole?
The eleven organ systems have a different set of functions, but they all work together, to maintain homeostasis
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.
Cells
Basic unit of life
What are the five general categories of sensory receptors?
pain receptors, thermorereceptors, mechanoreceptors, chemoreceptors, and photoreceptors
How does a moving impulse work?
1.) At Rest 2.) At the leading edge of the impulse, gates in the sodium channels open. The membrane becomes more permeable to Na+ ions 3.) As the action potential passes, gates in the potassium channels open, allowing K+ ions to flow out and restoring negative potential inside the axon 4.) The action potential continues to move along the axon
Cochlea
A coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses
Stimulant
A drug that increases the action of the central nervous system, the heart, and other organs
Fetal Alcohol Syndrome
A group of birth defects caused by the effects of alcohol on an unborn child
Organ Systems
A group of organs that work together in performing vital body functions.
Addiction
A physiological or psychological dependence on a drug
Reflex Arc
A relatively direct connection between a sensory neuron and a motor neuron that allows an extremely rapid response to a stimulus, often without conscious brain involvement.
Reflex
A simple, automatic, inborn response to a sensory stimulus, such as the knee-jerk response.
Organs
A structure consisting of several tissues adapted as a group to perform specific functions.
Somatic Nervous System
A subdivision of the peripheral nervous system. Enables voluntary actions to be undertaken due to its control of skeletal muscles
Myelin Sheath
Axon is surrounded by a clear membrane known as the Myelin Sheath.
Hypothalamus
Brain structure that acts as a control center for recognition and analysis of hunger, thirst, fatigue, anger, and body temperature
Thalamus
Brain structure that receives messages from the sense organs and relays the information to the proper region of the cerebrum for further processing
cones
Color vision
Depressants
Drugs that reduce neural activity and slow body functions.
How do Stimulants affect our body?
Increase heart rate, blood pressure, and breathing rate. In addition, stimulants increase the release of neurotransmitters at some synapses in the brain
Cerebrum
Largest part of brain, associated with higher order functioning including control of voluntary behaviour, e.g. Thinking, planning, perceiving, understanding language.
Synapse
Location at which a neuron can transfer an impulse to another cell
Axon
Long fiber that carries impulses away from the cell body. Axon ends in a series of small swellings called axon terminals, located some distance from the cell body.
What are the eleven organ systems?
Nervous System, Integumentary System, Respiratory System, Digestive System, Excretory System, Skeletal System, Muscular System, Circulatory System, Endocrine System, Reproductive System, Immune System
Sensory Receptors
Neurons that are specialized to detect a stimulus such as light, pressure, or heat
Sensory Neurons
Neurons that carry incoming information from the sensory receptors to the brain and spinal cord.
Motor neurons
Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.
rods
Retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond.
How do depressants affect our body?
Slow down heart rate and breathing rate, lower blood pressure, relax muscles, and relieve tension
Dendrites
Spreading out from the cell body are short, branched extensions called dendrites. Dendrites carry impulses from the environment or from other neurons toward the cell body
Pupil
The adjustable opening in the center of the eye through which light enters.
Homeostasis
The process by which organisms keep internal conditions relatively constant despite changes in external environments. Homeostasis in the body is maintained by feedback loops
How does a neuron maintain resting potential?
The sodium-potassium pump in the neuron cell membrane uses the energy of ATP to pump Na+ out of the cell and, at the same time to pump K+ in. This ongoing process maintains resting potential.
lens
The transparent structure behind the pupil that changes shape to help focus images on the retina.
menings
Three layers of connective tissue membrane that protect the brain and spinal cord
What happens when two neurons are joined together?
When an impulse reaches the end of the axon of one neuron, neurotransmitters are released into the synaptic cleft. The neurotransmitters blind to receptors on the membrane of an adjacent dendrite
Alcohol
a depressant that slows down the rate at which the CSN functions
Marijuana
a drug, often smoked, whose effects include euphoria, impairment of judgment and concentration and occasionally hallucinations; rarely reported as addictive
Muscle Tissue
along with bones, enables the body to move
drug
any substance other than food that changes the natural structure or function of the body
Cerebrospinal Fluid
bathes the brain and spinal cord and acts as a shock absorber that protects the CNS
Cocaine
causes the sudden release in the brain of a neurotransmitter called dopamine (Stimulant)
Specialized Cells
cells uniquely suited to perform a particular function
What are the levels of organization in a multicellular organism including tissues, organ systems, cells, and organs?
cells, tissues, organs, and organ systems
Neurotransmitters
chemicals used by a neuron to transmit an impulse across a synapses to another cell
Hypothalamus
contains nerve cells that monitor both the temperature of the skin at the surface of the body and the temperature of organs in the body's core
What does the neuron system do?
controls and coordinates functions throughout the body and responds to internal and external stimuli
The cerebellum
coordinates balance and body movements
Thermore Recep
detect variations in temeratutre
Resting Potential
electrical charge across the cell membrane of a resting neuron
What are the four lobes the brain is separated into?
frontal, parietal, temporal, occipital
Epithelial Tissues
glands and tissues that cover interior and exterior body surfaces
What two functions does the human ear have?
hearing and detecting positional changes associated with movement
What is the CNS
it is the control center of the body
Opiates
mimic natural chemcials in the brain known as endorphins, which normally help to overcome sensations of pain
Feedback Inhabitation
or negative feedback, is the process in which a stimulus produces a response that opposes the original stimulus (Like an automatic thermostat)
Connective Tissues
provides support for the body and connects its parts
What does the central nervous system do?
relays messages, processes information, and analyzes information
Pain Recep
respond to chemicals released by damaged cells
Action Potential
reversal of charges, from negative to positive, also called a nerve impulse
Chemo recp
sensative to chemicals in external enviornments
photo recep
sensative to light
Mechanore Recep
sensative to touch, pressure, stretching of muscles, sound, and motion
What can the peripheral nervous system be divided into?
sensory division and motor division
Taste buds
sensory organs that contain the receptors for taste
What are the three types of neurons?
sensory, motor, interneuorn
What is the motor division further divided into?
somatic and autonomtic nervous system
Brain Stem
structure that connects the brain and spinal cord; includes the medulla oblongata and the pons. Each of these regions regulates the flow of info between the brain and the rest of the body
What does the CNS consist of
the brain and spinal cord
Drug Abuse
the intentional improper or unsafe use of a drug
Cell body
the largest part of a typical neuron - contains nucleus and much of the cytoplasm
Automatic Nervous System
the part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes.
Semicircular Canals
three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with body movement
What does the sensory division do?
transmits impulses from sense organs to the central nervous system
What does the motor division do?
transmits impulses from the central nervous system to the muscles or glands
Nervous Tissue
transmits nerve impulses throughout the body
A neuron remains in its resting state until what?
until it receives a stimulus large enough to start a nerve impulse. The impulse causes a movement of ions across the cell membrane.
When does an impulse begin?
when a neuron is stimulated by another neuron or by the environment