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

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. UNIT B Chapter 10: Circulatory System and Lymphatic System TO PREVIOUS SLIDE 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 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.

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 UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System

UNIT B Section 10.6 Chapter 10: Circulatory System and Lymphatic System TO PREVIOUS SLIDE Figure 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.

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) UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System 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 UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System Movement of Lymph in Lymphatic Vessels

UNIT B TO PREVIOUS SLIDE Section 10.6 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

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 UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System Edema

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 UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System Lymphoid Organs

UNIT B Section 10.6 Chapter 10: Circulatory System and Lymphatic System TO PREVIOUS SLIDE Figure 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.

UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System 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 Primary Lymphoid Organs

UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System 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

Secondary Lymphoid Organs UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System 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

Secondary Lymphoid Organs UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System 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)

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. UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System

UNIT B TO PREVIOUS SLIDE Section 10.6 Chapter 10: Circulatory System and Lymphatic System