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THE LYMPHATIC

SYSTEM LAB

The lymphatic system has several primary functions: it participates in maintaining extracellular fluid balance, it absorbs fats and other substances from the digestive tract, and it functions in the immune system defense of the body. To do this, the lymphatic system is composed of a number of vessels and other structures. This exercise presents some of the basics of lymphatic anatomy and physiology.

A. Overview of the Lymphatic System

Use a chart, model, or your textbook, to find these gross features of the lymphatic system:

1. Identify these structures on the external aspect, ventral surface:

Locate some of the lymphatic vessels. These vessels are similar to veins in the structure of their walls and the presence of many valves. Lymph vessels collect lymph from interstitial spaces in the regions served and conduct it toward the blood circulation. Lymph, or lymphatic fluid, is an excess from interstitial areas. The right lymphatic duct is a large collecting vessel that receives lymph from the superior right quadrant of the body. The thoracic duct similarly conducts lymph received from the rest of the body. Each duct empties into a subclavian vein.

Lymph nodes are small, round organs located at irregular intervals in the network of lymph vessels. Like all lymph organs, they contain lymphatic tissue comprised mainly of lymphocytes (a category of white blood cells). They are distributed unevenly, with major aggregations of nodes in the neck (cervical nodes), armpit (axillary nodes), and groin (inguinal nodes).

The tonsils are lymph organs that surround the openings of the mouth, nose, and throat into the lower digestive and respiratory tracts. The palatine tonsils are on each lateral side of the opening of the mouth into the throat. The pharyngeal tonsils are at the top of the throat (pharynx) near the posterior of the nasal cavity. The lingual tonsils are on the posterior of the tongue's base.

The spleen and thymus should already be familiar to you. The spleen is located in the upper left abdominal cavity and the thymus is located in the anterior mediastinum.

B. The Lymph Node

There are numerous lymph nodes throughout the lymphatic system, as Figure 39.1 shows. Lymph usually passes through one or more lymph nodes on its path toward the blood circulation. The materials in lymph may stimulate lymphocyte development (an immune response) or may be destroyed by macrophages in the node. Identify these structures associated with the lymph node in a chart, model, or your textbook:

Afferent lymph vessels conduct lymph into a lymph node, whereas an efferent lymph vessel conducts lymph out of each node.

Within the node, lymph tissue often forms dense masses called lymph nodules. Each nodule contains a germinal center composed of rapidly dividing lymphocytes. Surrounding each node is a space through which lymph circulates; this space is called a lymph sinus. The sinuses also contain macrophages.

The fibrous capsule functions as the outer boundary and support structure for each lymph node. The inner surface of the capsule has inward extensions that separate the nodules from one another.

Figure 15-4 A diagram of a lymph node

[pic]

LYMPHATIC SYSTEM LAB REPORT

NAME(S) ______________________________________________________________ PERIOD ________

A. Multiple Choice Choose the best answer for the following.

_____1. Lymphatic tissue contains _____.

A. mainly lymphocytes

B. mainly erythrocytes

C. mainly monocytes

D. mainly thrombocytes

_____2. The large lymphatic organ found in the left hypochondriac region is the _____.

A. thymus

B. palatine tonsil

C. spleen

D. lingual tonsil

_____3. The lymph from tissues of the lower limbs is conducted by the _____.

A. right lymphatic duct

B. thoracic duct

_____4. Lymph nodes function to _____.

A. provide a site for lymphocyte maturation

B. anchor lymphatic vessels

C. provide a site for phagocytosis of foreign cells or debris

D. A and B are correct answers.

E. A and C are correct answers.

_____5. Lymph vessels that conduct lymph into a lymph node are termed _____.

A. efferent lymphatic vessels

B. efferent arterioles

C. afferent arterioles

D. afferent lymphatic vessels

_____6. The lymphatic system functions to _____.

A. maintain extracellular fluid balance

B. collect excess fluid from the interstitial spaces

C. defend the body against foreign cells and molecules

D. A, B, and C are correct answers.

_____7. Lymph drains directly into the blood at _____.

A. the right subclavian vein

B. the left subclavian vein

C. A and B are both correct answers.

_____ 8. These are specialized lymphatic structures found in the small intestines and

are involved fat absorption.

A. lymphocytes

B. lacteals

C. spleen

D. cisterni chili

B. Complete the Table

| | | |

|Lymphatic Structure |Location |Function(s) |

| | | |

|Lymphatic capillaries | | |

| | | |

| | | |

|Lymphatic vessels | | |

| | | |

| | | |

|Right lymphatic duct | | |

| | | |

| | | |

|Thoracic duct | | |

| | | |

| | | |

|Lymph node | | |

| | | |

| | | |

|Palatine tonsils | | |

| | | |

| | | |

|Pharyngeal tonsils | | |

| | | |

| | | |

|Lingual tonsils | | |

| | | |

| | | |

|Spleen | | |

| | | |

| | | |

|Thymus | | |

| | | |

C. Labeling Figure 39-1. Label the lymphatic structures indicated. The insert shows the drainage regions served by the two main lymphatic ducts. Name them using the word bank provided on the back page.

C. Labeling

1. ____________________________________

2. ____________________________________

3. ____________________________________

4. ____________________________________

5. ____________________________________

6. ____________________________________

7. ____________________________________

8. ____________________________________

9. ____________________________________

10. ____________________________________

WORD BANK

lymph vessel

right lymphatic duct (2)

spleen

thymus

cervical lymph nodes

thoracic duct (2)

inguinal lymph nodes

axillary nodes

-----------------------

(Afferent ducts)

(Efferent ducts)

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