Chapter 22: The Lymphatic System

1
Chapter 22 The Lymphatic System
2

• Pathogens
• Microscopic organisms that cause disease
• Viruses, bacteria, fungi, parasites
• The Lymphatic System
• Protects us against disease

3
What are the major components of the lymphatic
system and their functions?
4
Components of Lymphatic System

• Lymph
• Lymphatic vessels (lymphatics)
• Lymphoid tissues and organs
• Lymphocytes, phagocytes, and other immune system
  cells

5
Organization of the Lymphatic System
Figure 221
6
Functions of Lymphatic System

• production, maintenance and distribution of
  lymphocytes
• return of fluid and solutes from peripheral
  tissue to blood
• Distribution of hormones, nutrients and waste
  products from their tissue of origin to general
  circulation

7
Lymphocyte Production

• Lymphocytes are produced
• in lymphoid tissues (e.g., tonsils)
• lymphoid organs (e.g., spleen, thymus)
• and in red bone marrow

8

• Lymphatics
• Vessels that carry lymph from peripheral tissue
  to venous system
• Lymphatic vessels travel with veins

9

• Lymphatic Capillaries
• Differ from blood capillaries
• start as pockets rather than tubes
• have larger diameters
• have thinner walls

10

• Endothelial cells loosely bound together with
  overlap
• Overlap acts as one-way valve
• allows fluids, solutes, viruses, and bacteria to
  enter
• prevents return to intercellular space

11
Lymphatic Capillaries
Figure 222
12

• Lacteals
• special lymphatic capillaries in small intestine
• Transport lipids from digestive tract
• Lymph flows from lymphatic capillaries to larger
  lymphatic vessels containing one-way valves

13

• Vessels join to form large lymphatic trunks
• Trunks empty into 2 major collecting vessels
• thoracic duct
• right lymphatic duct

14
Lymphatic Vessels and Valves
Figure 223
15
Lymphatic Ducts and the Venous System
Figure 224
16
What are the structures and functions of
lymphoid tissues and organs?
17

• Lymphoid Tissues
• Connective tissues dominated by lymphocytes
• Lymphoid Nodule
• Areolar tissue with densely packed with dividing
  lymphocytes
• Lymph nodes, spleen, respiratory tract (tonsils),
  digestive tract (Peyers patches) and urinary
  tract

18
Lymphoid Organs

• Lymph nodes
• Thymus
• Spleen

19
Lymph Node

• Filter
• purifies lymph before return to venous
  circulation
• Removes
• debris
• pathogens
• 99 of antigens

20
The Thymus

• Located in mediastinum behind sternum
• Deteriorates after puberty
• Produces hormones that cause T lymphocytes to
  mature
• Thymosins

21
The Thymus
Figure 228
22
The Spleen

• largest lymphoid organ
• located along lateral border of the stomach
• Removes abnormal blood cells
• Stores recycled iron
• Initiation of immune responses by activating B
  cells and T cells

23
Structure of the Spleen

• Inside fibrous capsule
• red pulp
• which contains many red blood cells
• fixed and free macrophages
• white pulp
• resembles lymphoid nodules

24
The Spleen
Figure 229
25
What is the difference between nonspecific and
specific defense, and the role of lymphocytes
in the immune response?
26
Lymphocytes

• Lymphatic system cells respond to
• environmental pathogens
• toxins
• abnormal body cells, such as cancers
• 2 categories of defenses
• nonspecific defenses
• specific defenses

27
Specific Defenses

• Lymphocytes
• part of the immune response
• Identify, attack, and develop immunity
• ability to resist infection and disease
• protect against specific pathogens

28
Nonspecific Defenses

• Block or attack any potential infectious organism
• Cannot distinguish one attack from another
• Always work the same way against any type of
  invading agent

29
What are the bodys nonspecific defenses and
their functions?
30
Types of Nonspecific Resistance

• Physical barriers
• Phagocytic cells
• Immunological surveillance
• Interferons
• Complement
• Inflammation
• Fever

31
Nonspecific Defenses
Figure 2210
32
Physical Barriers

• Keep hazardous materials outside the body
• skin, mucous membranes, linings of tracts

33
Phagocytes

• Attack and remove dangerous microorganisms
• WBC that engulf large objects
• Can be fixed or free

34
Natural Killer cells

• Lymphocytes (NK cells)
• Immunological Surveillance
• Constantly monitors tissues
• recognize cells with abnormal membranes
• release perforin

35
Interferons

• Trigger production of antiviral proteins in
  normal cells
• Antiviral proteins
• do not kill viruses
• block replication in cell

36
Complement (C) Proteins

• Complements action of antibodies
• Plasma contains 11 specific C proteins
• Stimulation of inflammation
• Attraction of phagocytes
• Enhancement of phagocytosis

37
Inflammation

• Cardinal Signs
• Swelling, Redness, Heat, Pain
• Temporary barrier against pathogens
• Slows spread of pathogens
• Mobilization of defenses

38
Fever

• A high body temperature
• increases body metabolism
• accelerates defenses
• inhibits some viruses and bacteria
• Pyrogens causes the hypothalamus to raise body
  temperature
• circulating pathogens, toxins, or antibody
  complexes