Brain Central nervous system (CNS) Spinal cord Peripheral nervous system (PNS) Afferent division Efferent division Sensory stimuli Visceral stimuli Somatic nervous system Autonomic nervous system Motor neurons Sympathetic nervous system Parasympathetic nervous system Skeletal muscle Smooth muscle Cardiac muscle Glands Effector organs (made up of muscle and gland tissue) ( Input to CNS from periphery) ( Output from CNS to periphery)
The nervous and endocrine systems can be compared.
The nervous system transmits electrical impulses to skeletal muscles and the exocrine glands.
It is “wired”, sending electrical signals through distinct, highly organized pathways. These pathways have interconnected parts.
The endocrine system secretes hormones (chemical messengers) into the circulating blood to distant sites in the body.
These glands are not connected. They are scattered throughout the body.
An afferent neuron sends signals toward the CNS. It generates action potentials from sensory receptors at its peripheral end. It has a long axon and is found mainly in the PNS.
An efferent neuron sends signals away from the CNS to an effector organ. It has a long peripheral axon in the PNS.
An interneuron is found entirely within the CNS. It lies between afferent and efferent neurons.
Central nervous system (spinal cord) Peripheral nervous system Axon terminals Cell body Afferent neuron Central axon Peripheral axon (afferent fiber) R eceptor Interneuron Efferent neuron Effector organ (muscle or gland) Axon (efferent fiber) Axon terminals * Efferent autonomic nerve pathways consist of a two-neuron chain b etween the CNS and the effector organ. Cell body
Glial cells do not send signals. They support interneurons physically, metabolically, and functionally. There are four main kinds.
The astrocyte has many functions:
holding neurons together
guiding neurons during development
establishing a blood-brain barrier
repairing brain injuries
playing a role in neurotransmitter activity
taking up excess K + from the brain ECF
The oligodendrocyte forms myelin sheaths around axons in the CNS.
Microglia are the immune defense of the CNS.
They are scavengers.
Ependymal cells line the internal cavities of the CNS.
The brain stem is continuous with the spinal cord.
It consists of the midbrain, pons, and medulla. It controls life-sustaining processes such as breathing and digestion.
The cerebellum is attached to the top rear part of the brainstem.
It maintains balance, enhances muscle tone, and coordinates/plans skilled voluntary muscle activity.
The diencephalon is on top of the brain stem. It houses the:
hypothalamus - It controls many homeostatic functions that maintain the stability of the internal environment.
thalamus - It performs some primitive sensory processing.
The cerebrum is on top of the lower brain regions. It is highly developed in humans.
The cerebral cortex is its highly convoluted, outer layer of gray matter. It covers an inner core of white matter.
The cerebrum has an inner core of basal nucleii located deep within the white matter.
The electroencephalogram is a record of postsynaptic activity of cortical neurons.
It consists of various wave patterns.
It is used as a clinical tool in diagnosis of cerebral dysfunction.
It can distinguish various sleep stages.
It is used for legal determination of brain death.
The basal nucleii have an inhibitory role in motor control. Their functions include:
inhibiting muscle tone throughout the body
selecting and maintaining purposeful muscle activity while inhibiting useless movement
monitoring and controlling slow, sustained contractions
The thalamus is a relay station. It is also a synaptic integrating center for processing sensory input on its way to the cerebral cortex.
The hypothalamus regulates many homeostatic functions.
controlling body temperature
controlling thirst and urine production
controlling food intake
controlling anterior pituitary hormone secretion
production of posterior pituitary hormones
controls uterine contractions and milk ejection
serves as an ANS coordinating center
plays a role in emotional and behavioral patterns
The limbic system functions with the higher cortex.
It plays a key role in emotion.
It works with the higher cerebral cortex to control behavioral patterns.
The limbic system has reward and punishment centers.
The neurotransmitters in the pathways for emotional behavior include norepinephrine, dopamine, and serotonin.
The functions of the cerebellum include body balance and the planning and executing of voluntary movement.
The vestibulocerebellum maintains balance and controls body movement.
The spinocerebellum enhances muscle tone and coordinates skilled, voluntary movements.
The cerebrocerebellum plays a role in planning and initiating voluntary movement.
Top Front of brain Corpus callosum Cerebral cortex Thalamus (wall of third ventricular cavity) Pineal gland Cerebellum Part of the limbic system Bridge that connects the two halves of the thalamus Hypothalamus Pituitary gland Brain stem Spinal cord
Unfolded Regulation of muscle tone, coordination of skilled voluntary movement Planning and initiation of voluntary activity Maintenance of balance, control of eye movements Vestibulocerebellum Spinocerebellum Cerebrocerebelum
Motor cortex Spinocerebellum Informed of motor command Makes adjustments as necessary Motor command to muscles Informed of actual performance Activates receptors in muscles and joints Movement Skeletal muscles
The brain stem is the medulla, pons, and midbrain.
It is a vital link between the spinal cord and higher brain regions.
Most of the cranial nerves are connected to the brain stem.
It has centers to control heart and blood vessel function.
It plays a role in modulating the sense of pain.
It plays a role in regulating muscle reflexes involved in equilibrium and posture.
The reticular formation ranges from the brainstem to the thalamus. It controls cortical alertness and direct attention.
It has sleep centers.
Major Functions 1. Sensory perception 2. Voluntary control of movement 3. Language 4. Personality traits 5. Sophisticated mental events, such as thinking memory, decision making, creativity, and self-consciousness 1. Inhibition of muscle tone 2. Coordination of slow, sustained movements 3. Suppression of useless patterns of movements 1. Relay station for all synaptic input 2. Crude awareness of sensation 3. Some degree of consciousness 4. Role in motor control 1. Regualtion of many homeostatic functions, such as temperature control, thirst, urine output, and food intake 2. Important link between nervous and endocrine systems 3. Extensive involvement with emotion and basic behavioral patterns 1. Maintenance of balance 2. Enhancement of muscle tone 3. Coordination and planning of skilled voluntary muscle activity 1. Origin of majority of peripheral cranial nerves 2. Cardiovascular, respiratory, and digestive control centers 3. Regulation of muscle reflexes involved with equilibrium and posture 4. Reception and integration of all synaptic input from spinal cord; arousal and activation of cerebral cortex 5. Role in sleep-wake cycle Brain component Cerebral cortex Basal nuclei Thalamus Hypothalamus Cerebellum Brain stem (midbrain, pons, and medulla)