Intro to the Nervous System Flashcards
What is the nervous system?
One of the smallest and most complex body systems, made up of the brain, spinal cord and nerves helping to to control all our bodily functions.
-Mass of only 2kg (~3% of total body weight)
-Contains approx. 100 billion neurons
-Uses more energy than any other organ (over 20%)
-Highly organized network, 2 cell types:
- Neurons
- Neuroglia
Major components of the NS (6)
- Brain
- Spinal cord
- Cranial nerves
- Spinal nerves
- Ganglia
- Sensory receptors
2 Major Anatomical Divisions of NS
- Central Nervous System (CNS)
-Brain and spinal cord - Peripheral Nervous System (PNS)
-Cranial and spinal nerves, ganglia and sensory receptors
Nerve definition
Bundle of axons (nerve cell fibres) located outside the brain and spinal cord
Cranial Nerves (PNS)
-12 pairs of nerves (I-XII)
-Emerge from base of brain
Spinal Nerves (PNS)
-31 pairs of nerves
-Emerge from spinal cord
Ganglia (PNS)
-Clusters of neuron cell bodies
-Located outside CNS
*relay station for neurons
Sensory Receptors
-Monitor changes in environment
-Skin, eyes, nose, muscles, etc.
Functional Organization (3 Functions)
- Sensory Function (input)
- Integrative Function (control)
- Motor Function (output)
Sensory Function (Input)
-Sensory receptors detect internal and external stimuli
-Sensory (afferent) neurons transmit information to CNS
Integrative Function (Control)
-Interneurons (in CNS) analyze sensory information
-Involves perception (conscious awareness) of stimuli
Motor Function (Output)
-Motor (efferent) neurons respond to integration
-Initiate actions in effector organs (e.g. muscles, glands)
Afferent vs. Efferent Neurons
Afferent= sensory (to CNS)
Efferent= motor (response from CNS)
Divisions of the Nervous System
CNS:
-Brain and spinal cord
PNS:
-Somatic and autonomic nervous system
Autonomic System:
-Sympathetic and parasympathetic nervous system
Somatic Nervous System
- Somatic sensory neurons:
-Convey information TO CNS FROM sensory receptors for integration (input) - Somatic motor neurons:
-Convey information FROM CNS TO skeletal muscles for muscular contraction (output)
*regulates voluntary control of skeletal muscles
Autonomic Nervous System
- Sympathetic nervous system:
-Increase in activity and metabolic rate
-“Fight-or-flight” response
-Examples: dilate pupils, increase HR, inhibit intestinal activity - Parasympathetic nervous system:
-Decrease in activity and metabolic rate
-“Rest-or-digest” response
-Examples: constrict pupils, decrease HR, stimulate intestinal activity
*regulates involuntary control
2 Cell Types of the Nervous System
- Neurons
-Basic structural and functional units
-Form complex processing networks
-Transfer and process info - Neuroglia
-Smaller and more abundant
-Support, nourish and protect neurons
-Do not participate in transfer of info
*multiple neuroglia surround neurons
What is the Cerebrum
-Largest and most anterior part of the brain
-A.k.a telencephalon
-Consists of 2 hemispheres separated by a fissure
-Initiates and manages conscious thoughts and actions
Function of Cerebrum (Right vs. Left Hemispheres)
Involved in: reading, writing, speaking, doing logic calculations, making creative art, memory, planning, imagination
*right hemisphere more controls creativity, spatial ability, artistic skills
*left hemisphere more controls motor control, speech, abstract thinking
*both control movement on the contralateral side of the body
Components of the Cerebrum (4)
- Cerebral hemispheres
- White and grey matter (white= internal, grey= external)
- Gyrus and sulcus (gyrus= ridges, sulcus= folds)
- Cerebral cortex (outer layer that covers cerebrum)
2 Features of the Cerebrum
- Longitudinal fissure (separates right and left cerebral hemispheres)
- Corpus callosum (connects right and left hemispheres; “bridge”)
5 Lobes of Cerebrum and Their Functions
- Frontal lobe: executive functioning (planning, determining)
- Temporal lobe: auditory and speech
- Parietal lobe: touch and spatial recognition
- Occipital lobe: vision
- Insular lobe (insula): autonomic processes
*anterior to posterior, with insular lobe deep
Lobe Divisions of Cerebrum (3)
- Central sulcus: b/t frontal and parietal lobes (top)
- Lateral sulcus: b/t frontal and temporal lobes (side)
- Parieto-occipital sulcus: b/t parietal and occipital lobes (back)
Cerebellum Features (6)
- Folia (grey matter)
- Arbor vitae (white matter)
- Transverse fissure (b/t cerebellum and cerebrum)
- Cerebellar peduncles
- Cerebellar hemispheres
- Vermis (connects hemispheres)
*Tentorium cerebelli (restricts movement of cerebrum and cerebellum, separates cerebrum from cerebellum and brain stem)
Cerebellum Functions
-Coordinates voluntary movements
-Regulates posture and balance
Cerebellar Ataxia (Clinical Application)
-Uncoordinated movements due to lesion/damage to cerebellum and/or its cerebral connections
-Caused by stroke, alcohol misuse, tumour, multiple sclerosis, genetic disorders
CTE- Chronic Traumatic Encephalopathy (Clinical Application)
-Progressive, degenerative brain disorder
-Caused by concussions, repeated head injuries
-Involves atrophy of grey and white matter, makes the fissures bigger/more spread apart
