UNIT B: Human Body Systems

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UNIT B Human Body Systems

• Chapter 8 Human Organization
• Chapter 9 Digestive System
• Chapter 10 Circulatory System and Lymphatic
  System Section 10.7
• Chapter 11 Respiratory System
• Chapter 12 Nervous System
• Chapter 13 Urinary System
• Chapter 14 Reproductive System

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Chapter 10 Circulatory System and Lymphatic
System
UNIT B
Chapter 10 Circulatory System and Lymphatic
System

• In this chapter, you will learn about the
  structure and function of the circulatory system
  and lymphatic system.

What is the composition of blood, including blood
cells? What organs and structures control the
flow of blood throughout the body?
In 2013, Lance Armstrong confessed to long-term
blood doping and the use of banned substances.
Blood doping involves artificially boosting the
bloods ability to bring more oxygen to muscles.
Aerobic capacity and endurance improve where
there are additional red blood cells available to
carry oxygen.
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10.7 Innate and Adaptive Immunity
UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• The lymphatic system works with the immune system
  to protect the body from pathogens, toxins, and
  other invaders.
• Immunity is a condition where the body is
  protected from various threats (pathogens,
  toxins, cancer cells). There are two main types
  of immunity.
• Innate immunity Fully functional without
  previous exposure to substances
• Adaptive immunity Initiated and amplified after
  specific recognition of substances

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Innate Immunity
UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• Mechanisms of innate immunity can be divided into
  at least four types
• Physical and chemical barriers
• Inflammatory response
• Phagocytes and natural killer cells
• Protective proteins

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• Physical and Chemical Barriers

• Physical barriers
• Skin and mucous membranes lining the respiratory,
  digestive, and urinary tracts are physical
  barriers to pathogens
• Chemical barriers
• Oil glands in the skin secrete chemicals that
  weaken or kill certain bacteria
• The acidic pH of the stomach kills many types of
  bacteria or inhibits their growth
• Bacteria that reside in the intestine and other
  areas remove nutrients and block binding sites
  that could be used by pathogens

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• Inflammatory Response

• Inflammatory response
• A series of events that is initiated when there
  is damage to tissues by physical trauma, chemical
  agents, or pathogens
• Inflamed areas have four signs redness, heat,
  swelling, pain
• Mostly due to capillary changes in the damaged
  area
• At least three types of cells in the skin and
  connective tissue play a role in the inflammatory
  response
• Mast cells
• Macrophages
• Dendritic cells

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System
Figure 10.23 Inflammatory response. Due to
capillary changes in a damaged area and the
release of chemical mediators, such as histamine
by mast cells, an inflamed area exhibits redness,
heat, swelling, and pain. The inflammatory
reaction can be accompanied by other reactions to
the injury. Macrophages and dendritic cells,
present in the tissues, phagocytize pathogens, as
do neutrophils, which squeeze through capillary
walls from the blood. Macrophages and dendritic
cells release cytokines, which stimulate the
inflammatory and other immune reactions. A blood
clot can form to seal a break in a blood vessel.
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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• Inflammatory Response

• Mast cells
• Reside in the skin, lungs, and intestinal tract
• Respond to damage by releasing histamine
• Histamine causes capillaries in the area to
  dilate and become more permeable, allowing fluids
  to escape to tissues and cause swelling
• Swollen area stimulates free nerve endings,
  causing pain
• Increased blood flow causes skin to redden and
  warm

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• Inflammatory Response

• Macrophages and Dendritic Cells
• Both are phagocytic cells
• Release various proinflammatory cytokines, which
  are chemical messengers that influence other
  immune cells
• Interleukin-8 attracts other immune cells to the
  scene
• Colony-stimulating factor causes bone marrow to
  produce more white blood cells

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• Phagocytes and Natural Killer Cells

• Phagocytes
• Engulf pathogens into an endocytic vesicle, which
  fuses with a lysosome in the cell pathogen is
  destroyed by compounds in the lysosome
• Includes neutrophils and monocytes
• Neutrophils the first white blood cells to enter
  an inflamed area may accumulate to form pus
• Monocytes migrate from blood and differentiate
  into macrophages in tissues if inflammatory
  reaction continues

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• Phagocytes and Natural Killer Cells

• Natural killer (NK) cells
• Large, granular cells that kill some
  virus-infected and cancer cells by cell-to-cell
  contact
• NK cells induce target cells to undergo apoptosis
• Seek out and kill cells that lack a type of
  self molecule, called MHC-I (major
  histocompatibility class I), on their surface
• Some virus-infected and cancer cells lack MHC-I,
  which makes them susceptible to destruction by NK
  cells

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Adaptive Immunity
UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• Adaptive immunity is activated when innate
  defences fail to prevent an infection.
• The adaptive immune system recognizes, responds
  to, and usually eliminates antigens from the
  body.
• Antigens any molecules that stimulate an
  adaptive immune response
• Adaptive defences take 5 to 7 days to become
  fully activated and last for many years

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• The adaptive immune system depends on the
  activity of B cells and T cells.
• Both cells recognize antigens because they have
  specific antigen receptors
• Each lymphocyte has only one type of receptor
• Large diversity of antigen receptors on B and T
  cells
• There are specific B cells and/or T cells for
  almost any possible antigen

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• B Cells and Antibody-Mediated Immunity

• Defence by B cells (antibody-mediated immunity)
• B cells are activated in a lymph node or the
  spleen, when their receptors bind to specific
  antigens
• Cytokines secreted by T cells stimulate B cells
  to divide
• Most cells become plasma cells, which secrete
  antibodies
• Antibodies are the secreted form of the receptor
  of the B cell that was activated
• Some cells become memory B cells, which allow for
  long-term immunity
• If the same antigen enters again, memory B cells
  divide and give rise to more plasma cells that
  can produce the antibody against the antigen

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• B Cells and Antibody-Mediated Immunity

• Antibody Structure
• Antibodies are also called immunoglobulins (Ig),
  which are Y-shaped molecules with two arms made
  of polypeptides
• Heavy (long) polypeptide chain
• Light (short) polypeptide chain
• C (constant) region set sequence of amino acids
• V (variable) region amino acid sequence varies
  between antibodies forms the antigen-binding site

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System
Figure 10.24 Structure of an antibody. a. An
antibody contains two heavy (long) polypeptide
chains and two light (short) chains arranged so
that there are two variable regions, where a
particular antigen is capable of binding with an
antibody (V variable region, C constant
region). The shape of the antigen fits the shape
of the binding site. b. Computer model of an
antibody molecule. The antigen combines with the
two side branches.
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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• B Cells and Antibody-Mediated Immunity

• Antigens combine with an antibody at the
  antigen-binding site in a lock-and-key manner
• Antigen-antibody reactions can result in immune
  complexes (antigens combined with antibodies)
• Immune complexes may mark the antigens for
  destruction by a neutrophil or macrophage
• Antibodies can neutralize toxins by preventing
  them from binding to cells

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• T Cells and Cell-Mediated Immunity

• Defence by T cells (cell-mediated immunity)
• T cells have a unique T-cell receptor but cannot
  recognize antigens on their own
• Require antigens be presented to the receptors
  by an MHC (major histocompatibility complex)
  protein on the surface of another cell
• There are two types of T cells
• Helper T cells (TH cells)
• Cytotoxic T cells (TC cells or CTLs)

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• T Cells and Cell-Mediated Immunity

• Helper T cells (TH cells)
• Only recognize antigens presented by specialized
  antigen-presenting cells (APCs) with MHC class II
  proteins on their surface
• Cytotoxic T cells (TC cells or CTLs)
• Only recognize antigens presented by various
  cells with MHC class I proteins on their surface
• Some T cells become memory T cells
• Live for many years and can quickly initiate
  immune response to an antigen previously present
  in the body

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• T Cells and Cell-Mediated Immunity

• Cell-mediated immunity by TC cells
• Activated TC cells bound to a virus-infected or
  cancer cell release perforin, which forms pores
  in the plasma membranes of the abnormal cell
• This allows enzymes called granzymes to enter the
  target cell and induce apoptosis

Figure 10.25 Cell-mediated immunity. a. How a TC
cell destroys a virus-infected cell or cancer
cell.
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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

• T Cells and Cell-Mediated Immunity

• TC cells are capable of moving on to kill other
  target cells

Figure 10.25 Cell-mediated immunity. b. The
scanning electron micrograph shows cytotoxic T
cells attacking and destroying a cancer cell
(target cell).
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Check Your Progress
UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System

1. Name one physical and one chemical barrier to
   infection.
2. List the four cardinal signs of inflammation, and
   explain why each one occurs.
3. Contrast the way that macrophages typically kill
   pathogens with the method used by natural killer
   cells.
4. Compare the specific functions of helper T cells
   and cytotoxic T cells.

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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System
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UNIT B
Section 10.7
Chapter 10 Circulatory System and Lymphatic
System
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