Chapter 19 (the lymphatic system)

Pharyngeal Tonsils

(Adenoids) : In the posterior wall of the nasopharynx.

Thoracic Duct

(The larger one ) - Drains lymph from the rest of the body.

Right Lymphatic Duct

(the smaller one) - Drains lymph from right arm & right side of head & chest.

Mucosa- Associated Lymphatic Tissue (MALT)

- a collection of small lymphoid tissues that protect the body from inhaled or ingested pathogens; appendix, tonsils, peyer's patches (all located in the digestive tract) and lymph nodes in bronchi.

Where does the one-way network begin with the lymphatic vessels?

-It begins with microscopic lymphatic capillaries that weave between tissue cells and blood capillaries. - excess fluid and proteins from the interstitial fluid enter easily.

After lymph goes from the lymph capillaries, into larger lymphatic collecting vessels, and into lymphatic trunks.... Lymph is eventually collected into ?

1 of 2 large ducts

Functions of the Spleen:

1- Proliferation of Lymphocytes (cells) during the immune response. 2- Cleanses blood of old/defective blood cells, debris, foreign matter, bacteria, viruses, and toxins. 3- Stores breakdown products of RBCs for later reuse. 4- Site of erythrocytes (RBCs) production in the FETUS. 5- Stores blood thrombocytes (WBCs)

Functions of the lymphatic system

1- return excess fluid to the blood 2- Fight infections; provide resistance to disease

Because the Spleen's capsule is thin

A direct blow may cause it to rupture.

Lymph ENTERS the nodes via _______ lymphatic vessels.

Afferent

Lymphedema

Anything that prevents the normal return of lymph to blood results in severe, localized swelling called Lymphedema.

What is the function of Lymph Nodes?

As lymph is transported back to the bloodstream, it is filtered through clusters of lymph nodes.

Most of the fluid that is forced out of the blood is reabsorbed where?

At the Venous End.

At the arterial end of a capillary bed, what type of pressures force fluid out of the blood?

At the arterial end of a capillary bed, HYDROSTATIC and OSMOTIC PRESSURES force fluid out of the blood.

Hydrostatic and Osmotic pressures force fluid out of the blood at which end ?

At the arterial end of a capillary bed.

Why do Lymph Nodes exist?

Because pathogens & cancer cells enter lymph easily & spread thru body....

Thymus Anatomy

Bi-Lobed gland in lower neck that is most important in childhood.

Lymph EXITS the nodes via ____ vessels

Efferent .... allowing time for its cleansing.

lymph is eventually collected into 1 of 2 large ducts that empty that do what?

Empty into the venous circulation at the junction of the jugular (internal) & subclavian veins in the neck.

Tonsils Anatomy

Form a ring of lymphatic tissue around the entrance to the Pharynx ; where they appear as swellings of the mucosa; they are named according to location

From the lymph capillaries where does lymph flow into?

From the lymph capillaries, lymph flows next into larger lymphatic collecting vessels, and from there into lymphatic trunks.

Lymphatic vessels form a one- way network in which fluid flows only toward the ?

Heart

Where do lymphocytes arise?

In the red bone marrow

What is the flow of lymph maintained by?

It is maintained by the contraction of skeletal muscles, pressure changes in the chest (thoracic)(breathing), and pulsations in nearby arteries

The fluid that remains behind (3L/day) in the tissue space must eventually be returned where? and why?

It must be returned to the blood for the cardiovascular system to continue functioning.

Function of Thymus

It produces hormones that enable T cells (Lymphocytes) to function against specific pathogens during the immune response.

Macrophages

Large cells that phagocytize foreign substances and help to activate T cells (initiating the immune response)

Lingual Tonsils

Lies at the base of the tongue

Once fluid is inside of Lymphatic vessels, it is called

Lymph

"Swollen glands"

Lymph nodes may get overwhelmed by the pathogens they are filtering, become inflamed, swollen & painful.

The fluid that remains in the tissue space must eventually be returned to the blood for the cardiovascular system to continue functioning, this is the job of the?

Lymphatic Vessels

Returning excess fluid to blood is the first function of what?

Lymphatic Vessels.

Anything that prevents the normal return of lymph to blood results in severe, localized swelling called....

Lymphedema.

Lymph organs consist of 2 main types of cells

Lymphocytes Macrophages

How do lymph nodes activate the immune system?

Lymphocytes (B & T cells) in the nodes monitor lymph for the presence of antigens (foreign proteins) & mount an immune attack against them.

How do lymph nodes Filter lymph?

Macrophages in the nodes remove and destroy microbes and debris that entered lymph from infected tissue, preventing them from entering the blood.

T cells

Manage immune response; directly attack & destroy foreign cells

Palatine Tonsils

On either side at the posterior end of the oral cavity. They are the largest, and the most often infected, tonsils.

Types of tonsils

Palatine Lingual Pharyngeal

The flow of lymph is slow or fast?

Slow

2 types of lymphocytes

T cells and B cells

Spleen Anatomy?

The largest lymphoid organ, it is the size of a fist

Fluid only flows towards the heart because?

The lymphatic vessels for a one-way network in which fluid flows only toward the heart.

A system of drainage vessels that collect excess interstitial fluid to return it to the bloodstream

The lymphatics

Function of the tonsils

The tonsils gather and remove many pathogens entering the pharynx in inhaled air or food.

Lymphocytes in the Lymph Organs function

They are the main warriors of the immune system

Function of Lymphoid Organs

They fight infection; provide resistance to disease (2nd function of the system )

What is the first function of Lymphatic Vessels

They return excess fluid to blood.

This lymphoid organ does not directly fight against antigens, its only function is t- cells maturation

Thymus

What are the 2 basic functions of the lymph nodes?

To filter lymph & Activate the immune system

Examples of Lymphoid Organs include:

Tonsils, Thymus, spleen, peyer's patches, appendix.

Backflow of lymph is prevented by

Valves

Lymph organs are clusters of lymphatic tissue in the body. All are made of what type of tissue?

a type of reticular connective tissue

A splenectomy causes problems because

because the liver and bone marrow take over most of the spleen's functions.

B cells

develop into plasma cells which in turn secrete antibodies that immobilize the foreign substance (antigens) until it can be phagocytized.

The thymus is the only lymphoid organ that does NOT

directly fight antigens (its only function is T-lymphocytes maturation)

UNLIKE lymph nodes, the spleen, thymus, tonsils, and peyer's patches DO NOT

filter lymph ! (pathogens & debris)

Lymph are considered lymph when?

fluid is inside lymphatic vessels,

At the arterial end of a capillary bed, hydrostatic and osmotic pressures force what out of what?

force fluid out of the blood.

where is the spleen located?

in the left side of the abdominal cavity (LUQ) left upper quadrant. Just inferior to the diaphgram.

What is the size of the Thymus

the size of the thymus varies with age. -prominent in infants, it enlarges during child-hood, but stops growing in adolosenes, and then begins to atrophy, being almost entirely replaces by fibrous tissue in old age !

When a direct blow causes it to rupture....

the spleen must be removed quickly ( a splenectomy), and the splenic artery is tied off.

How many Lymph nodes are there?

there are hundreds of these bean-shaped nodes along lymphatic vessels.