Summary BIOL 1407 Exam 4 Study Guide

Exam 4 Outline



Chapter 28

The endocrine system, w/slower and more sustained responses/ the nervous system w/faster and less sustained
responses

 Neurons- nerve cells that transmit info via electrical/chemical signals
o Parts of a neuron
1. A cell body, containing the nucleus and other cell organelles
2. Long, thin extensions that convey signals
o 3 types of neurons & their function
1. Sensory neurons- convey signals from sensory
2. Interneurons- located entirely within the CNS, integrate data, and then relay appropriate signals
to other interneurons or to motor neurons
3. Motor neurons- convey signals from the CNS to effector cells
 3 interconnected functions of NS
1. Sensory input- the conduction of signals from sensory receptors
2. Integration- the analysis and interpretation of the sensory signals in the brain and spinal cord and the
formulation of appropriate responses
3. Motor output- the conduction signals from the integration centers through the PNS to effector cells,
such as muscle/gland cells, which perform the body’s responses
 2 Divisions of NS
o Central NS consists…
 Brain- master control center of NS
 Spinal cord- a jellylike bundle of nerve fibers that runs lengthwise inside the spine, which
conveys info to and from the brain and integrates simple responses to certain stimuli
o Peripheral NS consists...
 Nerves (bundles of neurons wrapped in connective tissue)
 Ganglia (clusters of neuron cell bodies)
 Peripheral NS has two functional components…
o Motor system
 Function- carries signals form the CNS to skeletal muscles, mainly in response to external stimuli
 Is mostly voluntary
o Autonomic nervous system composed of 3 divisions
 Function- regulates the internal environment by controlling smooth/cardiac muscles and the
organs/glands of the digestive, cardiovascular, excretory, and endocrine systems
 Is mostly involuntary
 Parasympathetic- primes the body for activities that gain and conserve energy for the body
 Sympathetic- prepares the body for intense, energy consuming activities
 Enteric- consists of networks of neurons in the digestive tract, pancreas, and gallbladder that
control secretion and peristalsis
 Neurons have two unique extensions arising from the neuron cell body
1. Dendrites- highly branched, often short, extensions that receive signals from other neurons and convey
this information toward the cell body
2. Axons- typically a much longer extension that transmits signals to other cells, which may be other
neurons or effector cells

,  A typical axon has hundreds or thousands of branches, each w/a synaptic terminal at the very end
 The junction between a synaptic terminal and another cell is called a synapse, or relay point
 At a synapse, electrical or chemical signals are transmitted to other neurons or effector cells
 Glia- supporting cells in neurons of all vertebrates and most invertebrates to function normally
 Myelin sheath- a Schwann cell, a type of glia found in the PNS, often wraps an axon along most of its length in a
thick insulating material
o Nodes of Ranvier- gaps between Schwann cells, an adaptation that increases the speed of signals along
an axon
 Blood-brain barrier- a vast network of blood vessels services the CNS and a selective mechanism, Function:
maintains a stable chemical environment for the brain
 Cerebrospinal fluid- found in and around the brain and spinal cord
o Ventricles- spaces in the brain filled with cerebrospinal fluid/ continuous with the narrow central canal
of the spinal cord
o Central canal- ventricles are continuous w/central canal of the spinal cord
 Meninges- layers of connective tissue that protects the brain and spinal cord
 Evolution of animal nervous systems
o Cephalization- the concentration of the nervous system at the head end
o Centralization-the presence of a central nervous system distinct from a peripheral nervous system
o Sponges- lack a nervous system
o Radially symmetrical animals,ex:cnidarians- have a diffuse web like system of interconnected neurons
extending throughout the body




Chapter 29

 Sensory reception
o Sensory receptors- specialized neurons or other cells that are tuned to the conditions of the external
world and internal organs; where all animals senses originate
 All sensory receptors trigger an action potential (nerve impulse)
 Send info to the central nervous sytem
 Five types and what they sense
1. Pain receptors- detect dangerous stimuli including high heat and pressure
2. Thermoreceptors- detect heat or cold
3. Mechanoreceptors- respond to mechanical energy such as touch/pressure, stretching,
motion, sound
4. Chemoreceptors- include sensory receptors in our nose and taste buds and respond to
chemicals
5. Electromagnetic receptors- respond to electricity, magnetism, various wavelengths of
light
o Sensory transduction- when the receptor cell converts one type of signal (the stimulus) to another type,
and electrical signal; produces a change in the cell’s membrane potential
o Receptor potential- changes in the flow of ions create a graded change in membrane potential in
sensory receptors cells
o Note: receptor potential vary; the stronger the stimulus, the greater the receptor potential
o Sensory adaptation- the tendency of some sensory receptors to become less sensitive when they are
stimulated repeatedly; repeated stimuli may lead to this