Transcript Chapter 10: Circulatory System and Lymphatic

UNIT B: Human Body Systems
Chapter 8: Human Organization
Chapter 9: Digestive System
Chapter 10: Circulatory System and
Lymphatic System: Section 10.6
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
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.
In 2013, Lance Armstrong confessed to long-term blood
doping and the use of banned substances. Blood doping
involves artificially boosting the blood’s 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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What is the composition of
blood, including blood cells?
What organs and structures
control the flow of blood
throughout the body?
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Chapter 10: Circulatory System and Lymphatic System
Section 10.6
10.6 The Lymphatic System
The lymphatic system consists of lymphatic vessels and the
lymphoid organs. It is closely associated with the circulatory
system.
The lymphatic system has three main functions:
• Lymphatic capillaries absorb excess tissue fluid and return it
to the bloodstream
• Lymphatic capillaries absorb fats from the digestive tract and
transport them to the bloodstream
• Lymphoid organs defend the body against disease
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Chapter 10: Circulatory System and Lymphatic System
Section 10.6
Figure 10.21 Lymphatic
system. Lymphatic vessels
drain excess fluid from the
tissues and return it to the
circulatory system. Lymphatic
vessels, like circulatory veins,
have valves to prevent
backward flow.
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Chapter 10: Circulatory System and Lymphatic System
Lymphatic Vessels
Lymphatic vessels form a one-way
system that begins with the
lymphatic capillaries.
Lymphatic capillaries (tiny,
closed-ended vessels) absorb
excess tissue fluid called lymph.
• Tissue fluid contains water,
solutes (nutrients, electrolytes,
oxygen), and cellular products
(hormones, enzymes, wastes)
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Section 10.6
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Chapter 10: Circulatory System and Lymphatic System
Movement of Lymph in Lymphatic Vessels
The lymphatic capillaries join to
form lymphatic vessels that merge
before entering one of two ducts:
• Thoracic duct: returns lymph
collected from the left side of the
body into the left subclavian vein
• Right lymphatic duct: returns
lymph collected from the right
side of the body into the right
subclavian vein
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Section 10.6
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Chapter 10: Circulatory System and Lymphatic System
Movement of Lymph in Lymphatic Vessels
• Lymph percolates through various lymph
nodes, where foreign material can be
recognized by the immune system
• Movement of lymph in the lymphatic
capillaries is dependent on skeletal muscle
contraction
• One-way valves in the vessels prevent
lymph from flowing backward
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Section 10.6
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Chapter 10: Circulatory System and Lymphatic System
Section 10.6
Edema
Edema is localized swelling caused by the accumulation of
tissue fluid that has not been collected by the lymphatic
system.
• Occurs if too much tissue fluid is made and/or if not
enough is drained away
• Can lead to tissue damage and death
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Chapter 10: Circulatory System and Lymphatic System
Section 10.6
Lymphoid Organs
Lymphoid organs contain large numbers of lymphocytes
(white blood cells involved in adaptive immunity).
There are two types of lymphoid organs:
• Primary lymphoid organs: red bone marrow and
thymus, where lymphocytes develop and mature
• Secondary lymphoid organs: lymph nodes and spleen,
where lymphocytes become activated
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Chapter 10: Circulatory System and Lymphatic System
Section 10.6
Figure 10.22 The lymphoid organs. The thymus (a) and red bone marrow (b)
are the primary lymphoid organs. Blood cells, including lymphocytes, are
produced in red bone marrow. B cells mature in the bone marrow. T cells mature
in the thymus. The lymph nodes (c) and the spleen (d) are secondary lymphoid
organs. Lymph is cleansed in the nodes, and blood is cleansed in the spleen.
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Chapter 10: Circulatory System and Lymphatic System
Primary Lymphoid Organs
Red bone marrow
• Contains a network of connective tissue
fibres, along with stem cells that can
divide and produce blood cells
• Lymphocytes begin development in the
bone marrow
o B lymphocytes (B cells) begin in
bone marrow and then migrate to
secondary lymphoid organs to mature
o T lymphocytes (T cells) begin in
bone marrow and then migrate to the
thymus, where they mature and
differentiate
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Section 10.6
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Chapter 10: Circulatory System and Lymphatic System
Primary Lymphoid Organs
Thymus
• Connective tissue divides the thymus
into lobules, which are filled with T
cells and supporting cells
• Lobules are lined with epithelial cells
that secrete hormones called
thymosins, which are involved in the
differentiation of T cells
• T cells that react to the body’s own
cells undergo apoptosis (programmed
cell death)
• T cells that leave the thymus can react
to foreign molecules
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Section 10.6
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Chapter 10: Circulatory System and Lymphatic System
Secondary Lymphoid Organs
Spleen
• Consists of blood vessels and sinuses
where macrophages remove old and
defective blood cells
• Also contains small areas of lymphoid
tissue, where lymphocytes can react
to foreign invaders in the blood
• May be surgically removed due to
trauma or disease, however the body
becomes more susceptible to certain
types of infections
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Section 10.6
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Chapter 10: Circulatory System and Lymphatic System
Secondary Lymphoid Organs
Lymph nodes
• Occur along lymphatic vessels
• Connective tissue divides nodes into
nodules, each of which contain B
cells, T cells, and a sinus
• As lymph passes through the sinuses,
macrophages engulf pathogens in the
lymph
• Cancer cells can enter the lymph
nodes and lymphatic vessels and
move through to other regions of the
body, where they produce secondary
tumours (metastasis)
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Section 10.6
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Chapter 10: Circulatory System and Lymphatic System
Section 10.6
Check Your Progress
1. Summarize the three functions of the lymphatic system.
2. Describe edema and its causes.
3. Identify and compare two primary and two secondary
lymphoid organs.
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Chapter 10: Circulatory System and Lymphatic System
Section 10.6