Divisions of the Nervous System Flashcards
what is the nervous system
- complex system of cells, chemicals, and organs that work together to produce behavior, thoughts, and actions.
- extensive network of specialized cells which carries information to and from all parts of the body
Functions of the Nervous System
- Senses the external and internal environment
- Communicates information to various body parts (especially the brain & spinal cord)
- Coordinates movements (involuntary and voluntary)
The Central Nervous System (CNS)
- the part of the nervous system consisting of the brain and spinal cord
What is the central nervous system composed of?
neurons and glial cells that control life-sustaining functions in the body, thought, emotion, and behavior
brain
- Core of the nervous system
- Makes sense of information received from senses
- Makes decisions and sends commands to muscles and the rest of the body
- master of human sexual behavior (such as attractiveness being a psychological factor)
spinal cord
long bundle of neurons that carries messages between the body and the brain;
responsible for life-saving reflexes
Outer (white) section of the SC
- composed mainly of myelinated axons and nerves
- Carries messages from the body to the brain, and from the brain to the body
Inner (gray) section of the SC
- mainly composed of cell bodies of neurons, separated by glial cells
- Primitive “brain” responsible for fast, life-saving reflexes
reflex arc
the connection of afferent neurons to interneurons to efferent neurons, resulting in a reflex action
Afferent (sensory) neuron
- neuron that carries information from senses to CNS
- Afferent neurons access the spinal cord
Efferent (motor) neuron
- neuron that carries messages from CNS to muscles and glands
- exit the spinal cord
Interneuron
- neuron that connects afferent (sensory) neurons to efferent (motor) neurons
- Makes up the bulk of neurons in the spinal cord and brain
What is the purpose of the reflex arc?
Because the message is not carried to the brain, this allows the body to respond much faster to stimuli – allowing for very fast reflexes
how does the The Spinal Cord Reflex in Action happen when touching a finger to a flame
- Flame stimulates pain receptors (sensory neurons)
- Sensory neurons excite interneurons in dorsal gray
portion of spinal cord - Interneurons excite motor neurons in ventral gray
portion of spinal cord - Motor nerves exit the spinal cord → excite muscle →
finger pulls away from flame
Peripheral nervous system (PNS)
all nerves and neurons that are not contained in the brain and spinal cord, but run through the body itself
Somatic nervous system
carries sensory information and controls movement of skeletal muscles
Voluntary or skeletal muscles
muscles that control the bones of the body and allow us to move
Autonomic nervous system (ANS)
- division of the PNS consisting of nerves that control all involuntary muscles, organs, and glands
- Automatically controls processes we aren’t aware of
Involuntary muscles
muscles not under our direct control, which are controlled by clumps of neurons on or near spinal column
Sympathetic Division (Fight or Flight)
The sympathetic division of the ANS is responsible for reacting to stressful events and bodily arousal.
Primarily located in the middle of the spinal column (near the top of rib cage to the waist)
“Fight or flight”
Allows us to deal with stressful events or emotions such as anger, fear, extreme joy or excitement
Parasympathetic Division (Rest and Digest)
responsible for restoring the body to its normal functioning after arousal and for the day-to-day functioning of organs and glands, which is active for most of the day.
Primarily located at top and bottom of spinal column
The Endocrine Glands
glands that secrete chemicals called hormones directly into the bloodstream
hormones
chemicals released into bloodstream by endocrine glands
Generally slower in reaching target organs– may not occur until hours, weeks, or years later
How do hormones interact with the nervous system and affect behavior?
They stimulate muscles, organs, or other glands of the body
Surges in some hormones can trigger emotional reactions
They can influence brain activity, producing excitatory or inhibitory effects
The Pituitary Gland
secretes human growth hormone
influences, controls, and balances hormones from all other endocrine glands (master gland)
Located below and controlled by the hypothalamus
Pineal gland
endocrine gland located near the base of the cerebrum
plays an important role in several biological rhythms
Secretes melatonin
melatonin
hormone that helps tracks day length and seasons
melatonin in animals
responsible for seasonal behaviors (breeding, molting)
humans
regulates sleep-wake cycle
Thyroid gland
endocrine gland found in the neck
involved in regulating growth and metabolism
Secretes thyroxin
thyroxin
hormone that regulates metabolism (how fast the body burns available energy), which is crucial role in body and brain development
Pancreas
endocrine gland that controls blood sugar levels
Secretes insulin and glucagon
Insulin
allows sugar to be absorbed into the body to turn into energy
effect of Too little insulin
diabetes (too much blood sugar in body)
effect of Too much insulin
hypoglycemia (low blood sugar)
Can cause excessive hunger
Gonads
sex glands that secrete hormones which regulate sexual development, behavior, reproduction
Include ovaries (female gonads) and testes (male gonads)
Adrenal glands
endocrine glands located on top of each kidney
secrete over 30 different hormones called coriticoids (which deal with stress, regulate salt intake, and provide a secondary source of sex hormones
Secretes cortisol
cortisol
Releases glucose into the bloodstream during stress (physical and emotional)
Releases fatty acids from fat cells to provide energy to muscles
Provides energy to the brain
