BIOL125 Lecture Notes - Lecture 8: Diphtheria Toxin, Nucleolus, Myosatellite Cell
8 Jun 2018
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Overview Nervous System Structure and Divisions
• 3.1. Overview of structure, function and location
o Structure
• The nervous system consists of the brain, spinal cord, sensory organs and all
the nerves that connect these organs with the rest of the body
• Made up of neural tissue
▪ Collections of neurons, neuroglia (support cells), associated blood
vessels and protective CT
▪ Neuron is the basic functional unit -groups of neurons arranged with cell
bodies together and axon bundled together
o Functions
• Body's quick messaging system (endocrine generally slow messaging system)
• Receives and interprets information about internal and external environment
- sensory ability via sensory receptors
• Uses information from multiple sources to develop coordinated responses -
integration/control centre ability
• Plans and executes responses from effectors (glands and muscle) - muscle
motor command (output ability)
• Coordinates or affects activities of other body systems
• Provides an immediate response to stimuli e.g. reflexes
o Location
• The brain and spinal cord form the control centre known as the CNS, where
information is evaluated and decisions made
• The sensory nerves and sense organs of the PNS monitor conditions inside
and outside of the body and send this information to the CNS
o Terminology
• Neural tissue - collection of neurons, neuroglia (support cells), associated
blood vessels and protective CT
• Neuron is the basic functional unit - groups of neurons arranged with cell
bodies together and axons bundled together
• Within the CNS
▪ Cortex of nucleus
• Grey matter
• Where cell bodies are grouped together
▪ Tract, fasciculus, lemniscus
• White matter
• Locations where myelinated axons are bundled
o Divisions of the NS
• Divided structurally (anatomically) or functionally
▪ Structurally
• CNS and PNS
• CNS cells and tissues contained within axial skeleton bones
▪ Functionally
• PNS divided in afferent/sensory division and efferent/motor
division
• Somatic (conscious) control and autonomic
(involuntary/subconscious) control
o 3.1.1. The functional divisions of the nervous system
• 3.1.1.1. sensory and motor
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▪ Sensory/afferent division brings sensory information to the CNS from
the peripheral sensory receptors: A = access CNS
▪ Motor/efferent division takes commands from CNS to effectors: E = exit
CNS
▪ Receptors detect changes in the internal and external environment and
respond to specific stimuli e.g. heat, cold, light touch receptors in skin,
and CO2 concentration and blood pressure receptors in arterial walls
▪ Receptors may be cytoplasmic extensions of a single cell e.g.
thermoreceptors or complex receptor organs e.g. eyes, ears
▪ Effectors are muscles, glands and adipose tissue - when stimulated they
change activity to cause desired effect e.g. to restore homeostasis
• 3.1.1.2. somatic and autonomic
▪ Somatic
• Controls contraction of skeletal muscle
• Voluntary/conscious control and involuntary/autonomic control
• Voluntary control allows for desired movement in the body
• Autonomic control examples
• Reflexes
• Contraction of diaphragm while asleep
• Respiratory muscles of inhalation and forced exhalation
• Contraction of bladder wall muscle if bladder is too full
• Autonomic control overrides conscious control to prevent damage
to body
▪ Autonomic
• Regulates smooth muscle, cardiac muscle, gland secretions and
adipose tissue at a subconscious level
• Two divisions
• Parasympathetic
• Controls everyday activity
• E.g. regular heart and breathing rate, digestion, sexual
arousal
• Sympathetic
• Activated in stressful conditions in the body
• e.g. emotional fear response -> increased heart and
breathing rate and increased pupil size - flight, fright,
fight response
o 3.1.2. The differences between the central nervous system and the peripheral
nervous system
• CNS
▪ Comprising of the brain, brainstem and spinal cord, plus supporting cells
and tissues e.g. astrocytes and oligodendrocytes
▪ Integrates, processes and coordinates both incoming sensory
information and outgoing motor commands
▪ e.g. when you trip on a path the CNS integrates incoming information
regarding position of the body in space and current balance, then
coordinated the correction for loss of balance via motor commands to
muscles
▪ Brain - regulates higher functions emotions, memory, learning and
intelligence
▪ Medulla oblongata - controls autonomic functions (breathing, dilation
and constriction of blood vessels, heart rate, etc.)
find more resources at oneclass.com
find more resources at oneclass.com
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Overview nervous system structure and divisions: 3. 1. Locations where myelinated axons are bundled: divisions of the ns, divided structurally (anatomically) or functionally. Structurally: cns and pns, cns cells and tissues contained within axial skeleton bones. Functionally: pns divided in afferent/sensory division and efferent/motor division. Somatic (conscious) control and autonomic (involuntary/subconscious) control: 3. 1. 1. The functional divisions of the nervous system: 3. 1. 1. 1. sensory and motor. Sensory/afferent division brings sensory information to the cns from the peripheral sensory receptors: a = access cns: motor/efferent division takes commands from cns to effectors: e = exit. Sympathetic: activated in stressful conditions in the body, e. g. emotional fear response -> increased heart and breathing rate and increased pupil size - flight, fright, fight response, 3. 1. 2. The differences between the central nervous system and the peripheral nervous system: cns, comprising of the brain, brainstem and spinal cord, plus supporting cells and tissues e. g. astrocytes and oligodendrocytes.
