Anatomy

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Anatomy Physiology Review

• Campbell Biology Chapters 11, 40, 43, 45, 48, 49

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Hierarchical Organization of Body Plans

• Cells ? Tissues ? Organs ? Organ Systems

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Homeostasis

• Maintain a steady state or internal balance
  regardless of external environment
• Fluctuations above/below a set point serve as a
  stimulus these are detected by a sensor and
  trigger a response
• The response returns the variable to the set
  point

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• Negative Feedback

• Positive Feedback

• More gets you less.
• Return changing conditions back to set point
• Examples
• Temperature
• Blood glucose levels
• Blood pH
• Plants response to water limitations

• More gets you more.
• Response moves variable further away from set
  point
• Stimulus amplifies a response
• Examples
• Lactation in mammals
• Onset of labor in childbirth
• Plants ripening of fruit

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Thermoregulation

• Maintain an internal temperature within a
  tolerable range
• Endothermic animals generate heat by metabolism
  (birds and mammals)
• Ectothermic animals gain heat from external
  sources (invertebrates, fishes, amphibians, and
  nonavian reptiles)

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Balancing Heat Loss and Gain

• Organisms exchange heat by four physical
  processes radiation, evaporation, convection,
  and conduction

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• Five adaptations for thermoregulation
• Insulation (skin, feather, fur, blubber)
• Circulatory adaptations (countercurrent exchange)
• Cooling by evaporative heat loss (sweat)
• Behavioral responses (shivering)
• Adjusting metabolic heat production (antifreeze)

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Torpor and Energy Conservation

• Torpor is a physiological state in which activity
  is low and metabolism decreases
• Save energy while avoiding difficult and
  dangerous conditions
• Hibernation torpor during winter cold and food
  scarcity
• Estivation summer torpor, survive long periods
  of high temperatures and scarce water

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Cell Signaling

• Animal cells communicate by
• Direct contact (gap junctions)
• Secreting local regulators (growth factors,
  neurotransmitters)
• Long distance (hormones)

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3 Stages of Cell Signaling

1. Reception Detection of a signal molecule
   (ligand) coming from outside the cell
2. Transduction Convert signal to a form that can
   bring about a cellular response
3. Response Cellular response to the signal
   molecule

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Response
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1. Reception

• Binding between signal molecule (ligand)
  receptor is highly specific.
• Types of Receptors
• Plasma membrane receptor
• water-soluble ligands
• Intracellular receptors (cytoplasm, nucleus)
• hydrophobic or small ligands
• Eg. testosterone or nitric oxide (NO)
• Ligand binds to receptor protein ? protein
  changes SHAPE ? initiates transduction signal

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G-Protein-Coupled Receptor
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Plasma Membrane Receptors
G-Protein Coupled Receptor (GPCR) Tyrosine Kinase Ligand-Gated Ion Channels
7 transmembrane segments in membrane Attaches (P) to tyrosine Signal on receptor changes shape
G protein GTP activates enzyme ? cell response Activate multiple cellular responses at once Regulate flow of specific ions (Ca2, Na)
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G-Protein-Coupled Receptor
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Receptor Tyrosine Kinase
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Ligand-Gated Ion Channel
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2. Transduction

• Cascades of molecular interactions relay signals
  from receptors ? target molecules
• Protein kinase enzyme that phosphorylates and
  activates proteins at next level
• Phosphorylation cascade enhance and amplify
  signal

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Second Messengers

• small, nonprotein molecules/ions that can relay
  signal inside cell
• Eg. cyclic AMP (cAMP), calcium ions (Ca2),
  inositol triphosphate (IP3)

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cAMP

• cAMP cyclic adenosine monophosphate
• GPCR ? adenylyl cyclase (convert ATP ? cAMP) ?
  activate protein kinase A

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3. Response

• Regulate protein synthesis by turning on/off
  genes in nucleus (gene expression)
• Regulate activity of proteins in cytoplasm

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Signal Transduction Pathway Problems/Defects

• Examples
• Diabetes
• Cholera
• Autoimmune disease
• Cancer
• Neurotoxins, poisons, pesticides
• Drugs (anesthetics, antihistamines, blood
  pressure meds)

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Cholera

• Toxin modifies G-protein involved in regulating
  salt water secretion
• G protein stuck in active form ? intestinal cells
  secrete salts, water
• Infected person develops profuse diarrhea and
  could die from loss of water and salts

• Disease acquired by drinking contaminated water
  (w/human feces)
• Bacteria (Vibrio cholerae) colonizes lining of
  small intestine and produces toxin

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Viagra

• Used as treatment for erectile dysfunction
• Inhibits hydrolysis of cGMP ? GMP
• Prolongs signal to relax smooth muscle in artery
  walls increase blood flow to penis

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Apoptosis cell suicide

• Cell is dismantled and digested
• Triggered by signals that activate cascade of
  suicide proteins (caspase)
• Why?
• Protect neighboring cells from damage
• Animal development maintenance
• May be involved in some diseases (Parkinsons,
  Alzheimers)

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• Endocrine System Hormone-secreting cells
  Tissues
• Endocrine glands ductless, secrete hormones
  directly into body fluids
• Hormones chemical signals that cause a response
  in target cells (receptor proteins for specific
  hormones)
• Affects 1 tissue, a few, or most tissues in body
• Or affect other endocrine glands (tropic
  hormones)
• Regulation by Positive Negative Feedback

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Pheromones Hormones Local Regulators
Chemical signal from 1 individual to another individual Chemical signal from endocrine gland through blood to target cell Chemical signal from one cell to an adjacent cell
Eg. ant trail sex phermones Eg. peptide, steroid hormones Eg. cytokines, growth factors, nitric oxide (NO)
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Types of Hormones

• Peptide

• Steroid

• Water-soluble
• Bind to receptors on plasma membrane triggers
  signal transduction pathway
• Affects protein activity already present in cell
• Rapid response
• Short-lived
• Eg. oxytocin, insulin, epinephrine

• Lipid-soluble
• Enters cell binds to intracellular receptors
• Causes change in gene expression (protein
  synthesis)
• Slower response
• Longer life
• Eg. androgens (testosterone), estrogen,
  progesterone, cortisol

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Epinephrine one hormone ? many effects

1. Liver cells break down glycogen and release
   glucose

1. Blood vessels to skeletal muscles dilate

1. Blood vessels to intestines constrict

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Master Glands
Hypothalamus
Pituitary Gland
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Master Glands

• Receives info from nerves and brain
• Initiates endocrine signals

Hypothalamus

• Posterior pituitary gland
• Oxytocin contract uterine muscles, eject milk in
  nursing
• Antidiuretic Hormone (ADH) promote H2O retention
  by kidneys

Pituitary Gland

• Anterior pituitary gland
• Follicle-stimulating hormone (FSH) development
  of ovarian follicles (eggs) promote sperm
  production
• Luteinizing hormone (LH) trigger ovulation
  stimulate testosterone production in testes

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Hypothalamus regulation of Anterior Pituitary
gland
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• Negative feedback systems
• Thyroid hormones
• Blood Ca2 levels
• Blood glucose levels
• Positive feedback system
• Oxytocin (birthing process release of
  milk/suckling)

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Insulin Glucagon Control blood glucose levels
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Organization of the Nervous System

• Central nervous system (CNS) brain spinal
  cord
• Peripheral nervous system (PNS) nerves
  throughout body
• Sensory receptors collect info
• Sensory neurons body ? CNS
• Motor neurons CNS ? body (muscles, glands)
• Interneurons connect sensory motor neurons
• Nerves bundles of neurons
• Contains motor neurons /or sensory neurons

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Neuron dendrite cell body axon
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Neuron

• cell body contains nucleus organelles
• dendrites receive incoming messages
• axons transmit messages away to other cells
• myelin sheath fatty insulation covering axon,
  speeds up nerve impulses
• synapse junction between 2 neurons
• neurotransmitter chemical messengers sent across
  synapse
• Glia cells that support neurons
• Eg. Schwann cells (forms myelin sheath)

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Schwann cells and the myelin sheath
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Membrane Potential difference in electrical
charge across cell membrane
Microelectrode
70 mV
Voltage recorder
Reference electrode
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The Na/K pump (using ATP) maintains a negative
potential inside the neuron.
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Action potentials (nerve impulses) are the
signals conducted by axons

• Resting potential membrane potential at rest
  polarized
• ?Na outside, ?K inside cell
• Voltage-gated Na channel CLOSED
• Nerve impulse stimulus causes a change in
  membrane potential
• Action potential neuron membrane depolarizes
• All-or-nothing response

K channels open
Na channels open
Na enters cell
K leaves cell
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Conduction of an action potential
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Saltatory conduction nerve impulse jumps between
nodes of Ranvier (unmyelinated gaps) ? speeds up
impulse
Saltatory conduction speed 120 m/sec
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Cell communication neurotransmitter released at
synapsesAxon (presynaptic cell) ? Dendrite
(postsynaptic cell)
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Neurotransmitters

• Chemicals released from vesicles by exocytosis
  into synaptic cleft
• Diffuse across synapse
• Bind to receptors on neurons, muscle cells, or
  gland cells
• Broken down by enzymes or taken back up into
  surrounding cells
• Types of neurotransmitters
• Excitatory speed up impulses by causing
  depolarization of postsynaptic membrane
• Inhibitory slow impulses by causing
  hyperpolarization of postsynaptic membrane

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• Acetylcholine (ACh) stimulates muscles, memory
  formation, learning
• Nicotine binds to ACh receptors ? inhibit cells
  ? increase heart rate
• Sarin nerve gas inhibits Ach breakdown ? ACh
  builds up ? paralysis and death
• Botulinum toxin (Botox) block ACh receptors on
  muscle cells ? prevent muscle contraction

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Neurotransmitters Other Examples

• Epinephrine (adrenaline) fight-or-flight
• Norepinephrine fight-or-flight
• Dopamine reward, pleasure (high)
• Loss of dopamine ? Parkinsons Disease
• Serotonin well-being, happiness
• Low levels ? Depression
• GABA inhibitory NT
• Affected by alcohol

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Vertebrate brain is regionally specialized

• Major Regions forebrain, midbrain, hindbrain

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• Forebrain ? cerebrum
• Midbrain ? brainstem
• Hindbrain ? cerebellum

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Human Brain
Structure Function
Cerebrum Information processing (learning, emotion, memory, perception, voluntary movement) Right Left cerebral hemispheres Corpus callosum connect hemispheres
Brainstem Oldest evolutionary part Basic, autonomic survival behaviors Medulla oblongata breathing, heart blood vessel activity, digestion, swallowing, vomiting Transfer info between PNS CNS
Cerebellum Coordinate movement balance Motor skill learning
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Types of Immunity
Innate Immunity Adaptive Immunity
Non-specific All plants animals Pathogen-specific Only in vertebrates Involves B and T cells
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Plant Defenses

• Nonspecific responses
• Receptors recognize pathogen molecules and
  trigger defense responses
• Thicken cell wall, produce antimicrobial
  compounds, cell death
• Localize effects

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Pathogens(such as bacteria,fungi, and viruses)
Barrier defenses
INNATE IMMUNITY(all animals)
SkinMucous membranesSecretions
Internal defenses
Phagocytic cellsNatural killer
cellsAntimicrobial proteinsInflammatory response
Rapid response
Humoral response
ADAPTIVE IMMUNITY(vertebrates only)
Antibodies defend againstinfection in body
fluids.
Cell-mediated response
Cytotoxic cells defendagainst infection in body
cells.
Slower response
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• Antimicrobial Proteins
• Interferons (inhibit viral reproduction)
• Complement system (30 proteins, membrane attack
  complex)

• Barrier Defenses
• Skin
• Mucous membranes
• Lysozyme (tears, saliva, mucus)

Innate Immunity (non-specific)

• Natural Killer Cells
• Virus-infected and cancer cells

• Inflammatory Response
• Mast cells release histamine
• Blood vessels dilate, increase permeability
  (redness, swelling)
• Deliver clotting agents, phagocytic cells
• Fever

• Phagocytic WBCs
• Neutrophils (engulf)
• Macrophage (big eaters)
• Eosinophils (parasites)
• Dendritic cells (adaptive response)

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Phagocytosis
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Inflammatory Response
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Lymphatic System involved in adaptive immunity
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Adaptive Response

• Lymphocytes (WBCs) produced by stem cells in
  bone marrow
• T cells mature in thymus
• helper T, cytotoxic T
• B cells stay and mature in bone marrow
• plasma cells ? antibodies

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• Antigen substance that elicits lymphocyte
  response
• Antibody (immunoglobulin Ig) protein made by B
  cell that binds to antigens

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Antigen-presenting cell
Cell-Mediated Immune Response (T Cells)
Humoral Immune Response (antibodies)
Helper T cell
B cell
Cytotoxic T cell
Plasma cell
tag for destruction
Identify and destroy
Infected cell
Antibodies
pathogen
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Major Histocompatibility Complex (MHC)

• Proteins displayed on cell surface
• Responsible for tissue/organ rejection (self
  vs. non-self)
• B and T cells bind to MHC molecule in adaptive
  response
• Class I all body cells (except RBCs)
• Class II displayed by immune cells non-self

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Immunological Memory

• Primary immune response 1st exposure to antigen
• Memory cells
• Secondary immune response repeat exposure ?
  faster, greater response

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B cells thatdiffer inantigenspecificity
Antigen
Antigenreceptor
Antibody
Plasma cells
Memory cells
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• Immunizations/vaccines induce immune memory to
  nonpathogenic microbe or toxin
• Passive immunity via antibodies in breast milk
• Allergies hypersensitive responses to harmless
  antigens
• Autoimmune Diseases
• Lupus, rheumatoid arthritis, Type I diabetes,
  multiple sclerosis
• HIV infect Helper T cells
• AIDS severely weakened immune system

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Latency
AIDS
Relative anti-HIV antibodyconcentration
800
Relative HIVconcentration
600
Helper T cell concentration(in blood (cells/mm3)
Helper T cellconcentration
400
200
0
0
9
1
2
3
4
5
6
7
8
10
Years after untreated infection
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Cancer and Immunity

• The frequency of certain cancers increases when
  adaptive immunity is impaired
• 20 of all human cancers involve viruses
• The immune system can act as a defense against
  viruses that cause cancer and cancer cells that
  harbor viruses
• In 2006, a vaccine was released that acts against
  human papillomavirus (HPV), a virus associated
  with cervical cancer