Chapter 35 - Nervous System Flashcards
What is homeostasis?
the process by which organisms keep internal conditions relatively constant despite changes in the external environments
What are neurons?
cells that transmit electrical signals (impulse)
What is the charge inside a neuron when it’s resting?
negative (K+)
What is the charge outside a neuron when it’s resting?
positive (Na+)
What happens during action potential?
At the front of the impulse, gates of the sodium (Na+) channels open, allowing Na+ to enter the neuron. The Na+ makes the neuron positive. As the impulse passes, gates within the potassium channels open, allowing K+ ions to flow out. This restores the negative charge of the neuron after the impulse.
What is threshold?
the minimum level of a stimulus that is required to activate a neuron (all or nothing)
How is homeostasis maintained?
feedback loops or inhibition
What is feedback inhibition?
process in which a stimulus produces a response that opposes the original stimulus (negative feedback) [heating system]
What are neurons?
cells that transmit electrical signals (impulse)
What is resting potential?
the electrical charge across the cell membrane of a neuron inits resting state
What is action potential?
a nerve impulse; reversal of charges from negative to positive
What happens during action potential?
At the front of the impulse, gates of the sodium (Na+) channels open, allowing Na+ to enter the neuron. The Na+ makes the neuron positive. As the impulse passes, gates within the potassium channels open, allowing K+ ions to flow out. This restores the negative charge of the neuron after the impulse.
What is threshold?
the minimum level of a stimulus that is required to activate a neuron (all or nothing)
What is synapse?
the location at which a neuron can transfer an impulse to another cell
What happens in a synapse?
When an impulse arrives at an axon terminal, the vesicles release the neurotransmitters into the synaptic cleft. The neurotransmitter molecules diffuse across the synaptic cleft and attach themselves to receptors on the membrane of the neighboring cell. If the stimulation exceeds the cell’s threshold, a new impulse begins
What are meninges?
3 layers of connective tissue that wrap the brain and spinal cord
What is cerebrospinal fluid?
bathes the brain and spinal cord and acts as a shock absorber that protects the central nervous system
What is the cerebrum?
- largest & most prominent part of brain
- responsible for voluntary activities
- site of intelligence, learning, and judgment
What helps increase the surface area of the cerebrum?
folds and grooves
Each hemisphere of the cerebrum is divided into regions called
lobes
Each half of the cerebrum deals mainly with the ___ side of the body
opposite
The outer layer of the cerebrum is called what?
cerebral cortex
What does the cerebral cortex consist of?
gray matter
What does the cerebral cortex do?
1) processes info from sense organs
2) controls body movements
The inner layer of the cerebrum consists of what?
White matter
What does white matter do?
connects the cerebral cortex and the brain stem
What is the cerebellum?
the second largest region of the brain
What does the cerebellum do?
coordinates and balances the actions of the muscles so that the body can move gracefully and efficiently
What does the brain stem do?
connects the brain and spinal cord
What are the two regions of the brain stem?
pons and medulla oblongata
What are some of the things that the brain stem controls?
blood pressure, heart rate, breathing, and swallowing
What does the thalamus do?
Receives messages from all of the sensory receptors throughout the body and then relays the info to the proper region of the cerebrum for further processing
What does the hypothalamus do?
- control center for recognition and analysis of hunger, thirst, fatigue, anger, and body temperature
- controls the coordination of the nervous and endocrine systems
What is a reflex?
a quick, automatic response to a stimulus
What does the central nervous system consist of?
the brain and the spinal cord
What does the peripheral nervous system consist of?
nerves and associated cells not part of the brain and spinal cord
What are ganglia?
collections of nerve cell bodies
The somatic system regulates activities that are under _____ control.
conscious (ex. movement of skeletal muscle)
The autonomic nervous system regulates activities that are
automatic or involuntary
The peripheral nervous system is divided into what?
sensory division and motor
What does the sensory division of the PNS do?
transmits impulses from sense organs to the central nervous system
What does the motor division of the PNS do?
transmits impulses from the central nervous system to the muscles or glands
The motor division is divided into what?
somatic and autonomic nervous systems
The autonomic nervous system is further divided into what?
sympathetic and parasympathetic nervous systems
What do the sympathetic and parasympathetic nervous systems do?
have opposite effect on each other in the same organ; sympathetic increases activity and parasympathetic decreases activity
