The lymphatic system consists of lymphatic ___

and lymphoid ___.

The lymphatic system consists of lymphatic

vessels and lymphoid tissues. 

 What is the basic function of the lymphatic vessels?

The basic function of the lymphatic vessels is

to collect materials from the interstitial fluid

and transport these materials through lymph

nodes and to the blood.

What kind of materials are collected from

the interstitial fluid and transported in

lymphatic vessels? 

Water, protein molecules, and various larger

particles are collected from the interstitial

fluid and transported in lymphatic vessels. 

Of what is lymphoid tissue composed? 

Lymphoid tissue is composed of lyphocytes,

macrophages, and dendritic cells in a frame-

work of recticular connective tissue. 

Lymphoid tissue is found in tiny structures

called ___ and larger structures called ___. 

Lymphoid tissue is found in tiny structures

called lymphoid nodules and larger structures

called lymphoid organs. 

Why is the protein composition of interstitial

fluid different from that of blood plasma? 

Because plasma proteins are too large to leave

blood capillaries, blood plasma has a higher

protein composition than interstitial fluid. 

Name three places in the body that do not

have lymphatic capillaries.

Lymphatic capillaries are absent from

bone marrow, cornea, and the central

nervous system. 

What is the functional significance of

overlapping endothelial cells in lymphatic

capillaries? 

Overlapping endothelial cells act as

one-way valves into the capillaries. 

How is lymph moved along the lymph vessels? 

Lymph is moved along the lymph vessels mainly

by pressure from outstide structures. These

include the contraction of skeletal muscles,

pulsations of nearby arteries, and the contraction

of digestive tract muscles. In the largest

lymphvessels, contractions of smooth muscle

push lymph. 

All the lymphatic vessels eventually empty

into one of two major lymphatic ducts.

What are they? 

All the lymphatic vessels eventually empty

either into the right lymphatic duct or the

thoracic duct. 

Which lymphatic duct receives lymph from

the upper-right quadrant of the body? 

The right lymphatic duct receives lymph from

the upper-right quadrant of the body. 

Into which duct does the thoracic duct empty? 

The thoracic duct empties into the left

subclavian vein. 

From which parts of the body does the inferior

thoracic duct receive lymph? 

The inferior thoracic duct receives lymph from

the abdomen and legs. 

What are chylomicrons? 

Chylomicrons are particles made from the

combinations of proteins and fat absorbed

by the system. 

Why are intestinal lypmphatic capillaries

called lacteals? 

Intestinal lymphatic capillaries are called

lateals because the lymph they carry has

a milky appearance due to the presence

of chylomicrons.

About how much lymph is returned each

day to the blood? 

About 3.6 liters of lymph is returned

each day to the blood. 

Most lymph nodes are shaped like ___

and range in size from ___ to ___. 

Most lymph nodes are shaped like a bean

and range in size from a millimeter to an

inch in size. 

Where in the body might one find

large clusters of lymph nodes? 

Large clusters of lymph nodes occur in

the inguinal, axillary, and cervical regions.

The connective tissue extensions of the

lymph node's connective tissue capsule

are called ___. 

The connective tissue extensions of the

lymph node's connective tissue capsule

are called trabeculae. 

Where, in the lymph node, do

lymphocytes multiply? 

Lymphocytes multiply in the germinal

centers located in the cortex (or outer

part) of the lymph node. 

What is the middle part of the

lymph node called? 

The middle part of the lymph

node is called the medulla. 

 Afferent vessels are located on the ___

side of the lymph node. Efferent vessels

are located on the ___ side. 

Afferent vessels are located on the convex

side of the lymph node. Efferent vessels

are located on the concave side. 

Lymph drains from the node in ___ vessels.

It enters the node via ___ vessels. 

Lymph drains from the node in efferent vessels.

It enters the node via afferent vessels. 

What are three functions of lymphatic

circulation? 

The lymphatic circulation returns interstitial

fluid and leaked proteins to the blood,

transports fats from the intestine to the blood,

and is a part of the body's defense against

infection. 

Why are the boundaries of the

lymphoid nodule indistinct? 

The boundaries of the lymphoid nodule are

indistinct because there is no fibrous

capsule surrounding the nodule. 

What happens in the central zone

of lymphoid nodules? 

Lymphoid nodules usually have a central

zone called the germinal center, which

contains dividing lymphocytes. 

Where are lymphoid nodules found? 

Lymphoid nodules are found in the

connective tissue of mucous membranes. 

By what name are lymphoid nodules

collectively known? 

Lymphoid nodules are collectively referred

to as mucosa-affilliated lymphoid tissue,

or MALT. 

What is significant about the location

of lymphoid nodules? 

Lymphoid nodules are near surfaces where

microbes could potentially enter. Therefore,

they are in a good position to defend the

body against microbes. 

What are the major structural differences

between lymphoid nodules and lymphoid organs?

Lymphoid organs are larger than lymphoid

nodules and they are surrounded with by a

fibrous connective tissue. 

Name three lymph organs. 

spleen, thymus, lymph nodes 

Where is the thymus located? 

The thymus is located posterior to the

sternum and superior to the heart. 

The thymus reaches its largest size

during what stage of life? 

The thymus reaches its largest size

during puberty. 

What is produced in the thymus? 

The thymus produces a class of cells

called T lymphocytes or T cells. 

Where is the spleen located? 

The spleen is located in the left part of the

abdominal cavity, lateral to the stomach. 

What two kinds of tissue are found in the

spleen and what happens in each? 

The spleen is composed of white pulp

(in which lymphocytes reside and multiply)

and red pulp

(where old RBCs and foreign material in

the blood are phagocytized). 

Name three functions of the spleen. 

The spleen removes abnormal blood cells,

 stores iron from recycled red blood cells,

and initiates immune defenses in response

to foreign materials in circulating blood.