Topic 9 Review
Name:
1. What are the basic levels of organization? Briefly describe each level.
Cells -> Tissues -> Organs -> Organ Systems-> Organisms
2. What is the basis of the endocrine system?
Involves glands that produce chemicals called hormones that are released into the
bloodstream and carried to specific glands
A hormone may affect one or more regions throughout the body
Hormones are relatively slow acting, but can have long-lasting effects
3. What is the basis of the nervous system? List the three types of cells that can
receive nerve impulses.
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Functional unit is the neuron (nerve cell)
Senses stimuli and transmits signals from one part of the body to another
part
Includes other neurons, glands, muscles and the brain
Neurons, Muscle Cells, and endocrine cells
4. What is homeostasis? Use the terms related to homeostatic controls (set
point), sensors, and response.
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Process by which animals maintain a relatively constant internal
environment, even when the external environment changes significantly
“steady state”
Homeostatic control systems function by having a set point (body
temperature), sensors to detect any stimulus above or below the set point,
and a physiological response that helps return the body to its set point
5. Compare and contrast negative-feedback systems and positive-feedback
systems.
C. Negative Feedback
• Animal response to the stimulus in a way that reduces the stimulus
• Ex: in response to exercise, the body temperature rises, which initiates
sweating to cool the body
Positive Feedback
• Involves a change in some variable that triggers mechanisms that amplify
rather than reverse the change
• Very unstable
• Ex: uterine contractions
6. What is thermoregulation?
Thermoregulation—refers to how animals maintain their internal temperature
within a tolerable range
Topic 9 Review
7.
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Compare and contrast endotherms and ectotherms.
Endotherms (warm blooded)
Ex: mammals and birds
Are warmed mostly by heat generated by metabolism
Ectotherms (cold blooded)
Ex: most invertebrates, fishes, amphibians, reptiles
Generate relatively little metabolic heat, gaining most of their heat from
external sources
In general, ectotherms tolerate greater variation in internal temperature,
while endotherms are active at a greater range of external temperatures
Endothermy is more energetically expensive than ectothermy
The body temperature of a poikilotherm varies with its environment, while
that of a homeotherm is relatively constant
8. What is countercurrent exchange?
This is the method by which many birds and mammals reduce heat loss
Heat transfer involves antiparallel arrangement of blood vessels such that warm
blood from the core of the animal, en route to the extremities, transfers heat to
colder blood returning form the extremities.
Heat that would have been lost to the environment is conserved in the blood
returning to the core of the animals
9. Compare and contrast hibernation and estivation. These are both types of
what process?
Torpor is a physiological state in which activity is low and metabolism decreases
Torpor enables animals to save energy while avoiding difficult and dangerous
conditions
Hibernation is long-term torpor that is an adaptation to winter cold and food
scarcity
• Estivation, or summer torpor, enables animals to survive long periods of high
temperatures and scarce water supplies
• Daily torpor is exhibited by many small mammals and birds and seems
adapted to feeding patterns
10. What are innate immune responses? Provide examples and briefly describe
the examples.
Innate immunity is present before any exposure to pathogens and is effective from
the time of birth
It involves nonspecific responses to pathogens
Innate immunity consists of external barriers plus internal cellular and chemical
defenses
Topic 9 Review
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11. What are phagocytic white blood cells? What are the different types?
A white blood cell engulfs a microbe, then fuses with a lysosome to destroy
the microbe
• There are different types of phagocytic cells:
Neutrophils engulf and destroy microbes
Macrophages are part of the lymphatic system and are found throughout the
body
Eosinophils discharge destructive enzymes
Dendritic cells stimulate development of acquired immunity
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12. What are antimicrobial proteins? What is it composed of?
• Antimicrobial Peptides and Proteins - Peptides and proteins function in
innate defense by attacking microbes directly or impeding their reproduction
• Interferon proteins provide innate defense against viruses and help activate
macrophages
• About 30 proteins make up the complement system, which causes lysis of
invading cells and helps trigger inflammation
13. What is an inflammatory respsonse?
Following an injury, mast cells release histamine, which promotes changes in
blood vessels; this is part of the inflammatory response
These changes increase local blood supply and allow more phagocytes and
antimicrobial proteins to enter tissues
Pus, a fluid rich in white blood cells, dead microbes, and cell debris, accumulates at
the site of inflammation
14. What are histamines and what are they released by?
Following an injury, mast cells release histamine, which promotes changes in
blood vessels
15. What are natural killer cells?
All cells in the body (except red blood cells) have a class 1 MHC protein on their
surface
Cancerous or infected cells no longer express this protein; natural killer (NK) cells
attack these damaged cells
16. Compare and contrast antigens and antibodies.
An antigen is any foreign molecule to which a lymphocyte responds
• A single B cell or T cell has about 100,000 identical antigen receptors. All
antigen receptors on a single lymphocyte recognize the same epitope,
or antigenic determinant, on an antigen
• B cells give rise to plasma cells, which secrete proteins called
antibodies or immunoglobulins
Topic 9 Review
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17. Compare and contrast B lymphocytes and T lymphocytes.
White blood cells called lymphocytes recognize and respond to antigens, foreign
molecules
Lymphocytes that mature in the thymus above the heart are called T cells, and
those that mature in bone marrow are called B cells.
• B cell receptors bind to specific, intact antigens
• The B cell receptor consists of two identical heavy chains and two identical
light chains
• The tips of the chains form a constant (C) region, and each chain contains a
variable (V) region, so named because its amino acid sequence varies
extensively from one B cell to another
• Secreted antibodies, or immunoglobulins, are structurally similar to B cell
receptors but lack transmembrane regions that anchor receptors in the
plasma membrane
• Each T cell receptor consists of two different polypeptide chains
• The tips of the chain form a variable (V) region; the rest is a constant (C)
region
• T cells can bind to an antigen that is free or on the surface of a pathogen
18. What is clonal selection?
In the body there are few lymphocytes with antigen receptors for any particular
epitope
The binding of a mature lymphocyte to an antigen induces the lymphocyte to divide
rapidly
This proliferation of lymphocytes is called clonal selection
19. Compare and contrast effector cells and memory cells.
Two types of clones are produced: short-lived activated effector cells and longlived memory cells
20. What is the MHC? What are the two classes? Where are they found?
T cells bind to antigen fragments presented on a host cell
These antigen fragments are bound to cell-surface proteins called MHC molecules
• MHC molecules are so named because they are encoded by a family of genes
called the major histocompatibility complex.
• In infected cells, MHC molecules bind and transport antigen fragments
to the cell surface, a process called antigen presentation
• A nearby T cell can then detect the antigen fragment displayed on the
cell’s surface
• Depending on their source, peptide antigens are handled by different
classes of MHC molecules
• Class I MHC molecules are found on almost all nucleated cells of the body
• They display peptide antigens to cytotoxic T cells
• Class II MHC molecules are located mainly on dendritic cells, macrophages,
and B cells
Topic 9 Review
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Dendritic cells, macrophages, and B cells are antigen-presenting cells that
display antigens to cytotoxic T cells and helper T cells
21. How is the specificity of the B and T cells obtained? What do B cells make?
Differences in the variable region account for specificity of antigen receptors
The immunoglobulin (Ig) gene encodes one chain of the B cell receptor
Many different chains can be produced from the same Ig chain gene by
rearrangement of the DNA
Rearranged DNA is transcribed and translated and the antigen receptor formed
22. Compare and contrast primary and secondary immune response.
The first exposure to a specific antigen represents the primary immune response
During this time, effector B cells called plasma cells are generated, and T cells are
activated to their effector forms
In the secondary immune response, memory cells facilitate a faster, more efficient
response
23. What are the two branches of acquire immunity? Briefly describe them
Acquired immunity has two branches: the humoral immune response and the cellmediated immune response
Humoral immune response involves activation and clonal selection of B cells,
resulting in production of secreted antibodies
Cell-mediated immune response involves activation and clonal selection of
cytotoxic T cells
Helper T cells aid both responses
24. What role do helper T cells play in acquired immunity?
A surface protein called CD4 binds the class II MHC molecule
This binding keeps the helper T cell joined to the antigen-presenting cell while
activation occurs
Activated helper T cells secrete cytokines that stimulate other lymphocytes
25. What role do cytotoxic T cells play in acquired immunity?
Cytotoxic T cells are the effector cells in cell-mediated immune response
Cytotoxic T cells make CD8, a surface protein that greatly enhances interaction
between a target cell and a cytotoxic T cell
Binding to a class I MHC complex on an infected cell activates a cytotoxic T cell and
makes it an active killer
The activated cytotoxic T cell secretes proteins that destroy the infected target cell
26. List and briefly describe the three modes of antibody action.
Neutralization occurs when a pathogen can no longer infect a host because it is
bound to an antibody
Opsonization occurs when antibodies bound to antigens increase phagocytosis
Antibodies together with proteins of the complement system generate a membrane
attack complex and cell lysis
Topic 9 Review
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27. Compare and contrast active and passive immunity.
Active immunity develops naturally in response to an infection
It can also develop following immunization, also called vaccination
In immunization, a nonpathogenic form of a microbe or part of a microbe elicits an
immune response to an immunological memory
Passive immunity provides immediate, short-term protection
• It is conferred naturally when IgG crosses the placenta from mother to fetus
or when IgA passes from mother to infant in breast milk
• It can be conferred artificially by injecting antibodies into a nonimmune
person
28. What is HIV?
Acquired immunodeficiency results from exposure to chemical and biological agents
Acquired immunodeficiency syndrome (AIDS) is caused by a virus
• Human immunodeficiency virus (HIV) infects helper T cells
• The loss of helper T cells impairs both the humoral and cell-mediated
immune responses and leads to AIDS
• HIV eludes the immune system because of antigenic variation and an ability
to remain latent while integrated into host DNA
• People with AIDS are highly susceptible to opportunistic infections and
cancers that take advantage of an immune system in collapse
• The spread of HIV is a worldwide problem
• The best approach for slowing this spread is education about practices that
transmit the virus
29. What are endocrine glands?
Endocrine signals (hormones) are secreted into extracellular fluids and travel via
the bloodstream
Endocrine glands are ductless and secrete hormones directly into surrounding
fluid
Hormones mediate responses to environmental stimuli and regulate growth,
development, and reproduction
30. What are hormones?
• Animal hormones are chemical signals that are secreted into the circulatory
system and communicate regulatory messages within the body. Hormones
reach all parts of the body, but only target cells are equipped to respond
31. List and briefly describe the two types of receptors of hormone action.
Cell- surface receptors – bind the hormone, and a signal transuction pathway is
triggered. A signal transduction pathway consists of a series of molecular events
that initiate a response to the signal. Example: The binding of epinephrine to liver
cells causes a cascade that leads to the conversion of glycogen to glucose
Intracellular receptors – are bound by hormones that are lipid-soluble. The receptor
then acts as a transcripton factor, causing a change in gene expression. Example:
Topic 9 Review
Name:
Testosterone and estrogen enter the nuclei of target cells, bind the DNA, and
stimulate transcription of certain genes.
32. What is a neuron?
Neurons are nerve cells that transfer information within the body
Neurons use two types of signals to communicate: electrical signals (long-distance)
and chemical signals (short-distance)
33. What are the parts to a neuron? Be able to diagram a neuron.
Fig. 48-4
Dendrites
Stimulus
Nucleus
Presynaptic
Axon cell
Cell hillock
body
Axon
34. What is a synapse?
A synapse is a junction between an axon and another cell
The synaptic terminal of one axon passes information across the synapse in the
form of chemical messengers called neurotransmitters
35. What are neurotransmitters?
Topic 9 Review
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36. Compare and contrast the central nervous system and peripheral nervous
system.
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A central nervous system (CNS) where integration takes place; this
includes the brain and a nerve cord
A peripheral nervous system (PNS), which brings information into
and out of the CNS
The CNS is composed of the brain and spinal cord
The peripheral nervous system (PNS) is composed of nerves and
ganglia
The PNS transmits information to and from the CNS and regulates
movement and the internal environment
37. What are sensory neurons, interneurons, and motor neurons?
Sensors detect external stimuli and internal conditions and transmit information
along sensory neurons
Sensory information is sent to the brain or ganglia, where interneurons integrate
the information
Motor output leaves the brain or ganglia via motor neurons, which trigger muscle
or gland activity
38. Compare membrane potential and resting potential.
Every cell has a voltage (difference in electrical charge) across its plasma membrane
called a membrane potential
Messages are transmitted as changes in membrane potential
The resting potential is the membrane potential of a neuron not sending signals
39. Study the image on pg. 245 concerning the conduction of an action potential.
Be able to explain the following terms: refractory period and threshold.
At resting potential
1. Most voltage-gated Na+ and K+ channels are closed, but some K+ channels
(not voltage-gated) are open
When an action potential is generated
2. Voltage-gated Na+ channels open first and Na+ flows into the cell
3. During the rising phase, the threshold is crossed, and the membrane potential
increases
4. During the falling phase, voltage-gated Na+ channels become inactivated;
voltage-gated K+ channels open, and K+ flows out of the cell
5. During the undershoot, membrane permeability to K+ is at first higher than at
rest, then voltage-gated K+ channels close; resting potential is restored
During the refractory period after an action potential, a second action potential
cannot be initiated
The refractory period is a result of a temporary inactivation of the Na+ channels
Topic 9 Review
Name:
40. Briefly explain what happens in the synapse using the image on pg. 246.
At electrical synapses, the electrical current flows from one neuron to another
At chemical synapses, a chemical neurotransmitter carries information across the
gap junction
Most synapses are chemical synapses
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The presynaptic neuron synthesizes and packages the neurotransmitter in
synaptic vesicles located in the synaptic terminal
The action potential causes the release of the neurotransmitter
The neurotransmitter diffuses across the synaptic cleft and is received by
the postsynaptic cell
Direct synaptic transmission involves binding of neurotransmitters to ligandgated ion channels in the postsynaptic cell
Neurotransmitter binding causes ion channels to open, generating a
postsynaptic potential
41. List the four common neurotransmitters.
-Acetylcholine is a common neurotransmitter in vertebrates and invertebrates
In vertebrates it is usually an excitatory transmitter
-Biogenic amines include epinephrine, norepinephrine, dopamine, and
serotonin
• They are active in the CNS and PNS
-Two amino acids are known to function as major neurotransmitters in the CNS:
gamma-aminobutyric acid (GABA) and glutamate
-Several neuropeptides, relatively short chains of amino acids, also function as
neurotransmitters
• Neuropeptides include substance P and endorphins, which both affect our
perception of pain
• Opiates bind to the same receptors as endorphins and can be used as
painkillers
Acetylcholine, epinephrine, norepinephrine, dopamine, and serotonin
42. What is a reflex?
reflex is the body’s automatic response to a stimulus
– For example, a doctor uses a mallet to trigger a knee-jerk reflex
43. Compare and contrast gray and white matter.
The brain and spinal cord contain
– Gray matter, which consists of neuron cell bodies, dendrites, and
unmyelinated axons
– White matter, which consists of bundles of myelinated axons
44. What are glia?
Cells that support neurons.
Topic 9 Review
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45. List and briefly describe the three important types of glia.
Three important kinds of glia are astrocytes, which provide support for neurons;
oligodendrocytes, which form myelin sheaths in the CNS; and Schwann Cells, which
form myelin sheaths in the PNS.
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Astrocytes provide structural support for neurons, regulate
extracellular ions and neurotransmitters, and induce the formation of
a blood-brain barrier that regulates the chemical environment of the
CNS
Radial glia play a role in the embryonic development of the nervous
system
46. What is the autonomic nervous system? What are the two divisions? Briefly
describe them.
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The autonomic nervous system regulates the internal environment in an
involuntary manner
The autonomic nervous system has sympathetic, parasympathetic, and
enteric divisions
The sympathetic and parasympathetic divisions have antagonistic effects on
target organs
The sympathetic division correlates with the “fight-or-flight” response
The parasympathetic division promotes a return to “rest and digest”
The enteric division controls activity of the digestive tract, pancreas, and
gallbladder
47. What is the general function of the following parts of the brain:
Structure
Function
Brainstem
The brainstem coordinates and conducts information
between brain centers
The brainstem has three parts: the midbrain, the pons, and
the medulla oblongata
The midbrain contains centers for receipt and integration of
sensory information
The pons regulates breathing centers in the medulla
The medulla oblongata contains centers that control several
functions including breathing, cardiovascular activity,
swallowing, vomiting, and digestion
The brainstem and cerebrum control arousal and sleep
The core of the brainstem has a diffuse network of neurons
called the reticular formation
This regulates the amount and type of information that
Topic 9 Review
Cerebellum
Thalamus
Hypothalamus
Cerebrum
Cerebral cortex
Corpus Collosum
Name:
reaches the cerebral cortex and affects alertness
The hormone melatonin is released by the pineal gland and
plays a role in bird and mammal sleep cycles
The cerebellum is important for coordination and error
checking during motor, perceptual, and cognitive functions
It is also involved in learning and remembering motor skills
The thalamus is the main input center for sensory
information to the cerebrum and the main output center for
motor information leaving the cerebrum
The hypothalamus regulates homeostasis and basic survival
behaviors such as feeding, fighting, fleeing, and reproducing
As a human brain develops further, the most profound
change occurs in the forebrain, which gives rise to the
cerebrum
The outer portion of the cerebrum called the cerebral
cortex surrounds much of the brain
A thick band of axons called the corpus callosum provides
communication between the right and left cerebral cortices
The right half of the cerebral cortex controls the left side of
the body, and vice versa