A&P 2 Chapter 20 review

Compare and contrast blood, interstitial fluid, and lymph

. Blood, the carrier of nutrients, wastes, and gases, circulates within blood vessels through the body, exchanging materials with the interstitial fluid. . Interstitial fluid, formed by filtration from blood, is the fluid surrounding body cells in the tissue spaces and is essential to proteinless plasma. . Lymph is the protein-containing fluid that enters the lymphatic capillaries (from the tissue spaces); hence, its composition is the same as that of the interstitial fluid.

5 structures without lymph vessels

. CNS . bone . cartilage . epidermis . teeth

Outermost layer composed of connective tissue

Capsule

Appendix

. tubular offshoot of the first part of the large intestine and contains a high concentration of lymphoid follicles . function is destroy bacteria preventing them from breaching intestinal wall & generate memory lymphocytes

Interstitial fluid that enters lymph vessels is called ___1___. These fluids are lost from the ___2___ end of the capillary because of ___3___ pressure.

1. Lymph 2. Arteriole 3. Capillary hydrostatic pressure

Lymphoid organs

> Grouped into 2 functional categories . Primary lymphoid organ - where T & B cells mature (red bone marrow and the thymus) T cells originate in RBM but mature in the thymus, while B cells originate in RBM and mature in RBM . Secondary lymphoid organs - where mature lymphocytes first encounter their antigens and are activated. Include lymph nodes, spleen, and mucosa associated lymphoid tissue (MALT) that form the tonsils , peyer's patches in the small intestine , and the appendix.

Lymph nodes are densely clustered in all the following body areas except a: the brain b: the axillae c: the groin d: the cervical region

A

The red pulp area of the spleen are sites of a: splenic sinusoids , macrophages, and RBCs b: clustered lymphocytes c: connective tissue septa

A

Entry of lymph into the lymphatic capallaries is promoted by which of the following? a: 1 way mini-valves formed by overlapping endothelial cells b: the respiratory pump c: the skeletal muscle pump d: greater fluid pressure in the interstitial space

A & D

Vessel that brings fluid into node

Afferent vessels

Mass of lymphoid tissue at the end of cecum

Appendix

Capillary bulk exchange and how lymph is formed

At the arteriole end of the blood capillaries there is high hydrostatic pressure , which causes the filtering of fluids and solutes out of the blood into tissue. As blood proceeds in the capillaries to the venule end the capillary hydrostatic pressure drops (due to unfiltered plasma proteins, mainly albumins) is high and is a pulling pressure that causes interstitial fluid & waste re-absorption of 90%of the fluid that left in the filtering step. The remaining 10% of the interstitial fluid is picked up by the lymphatics

The lymphoid organ that functions properly during youth and then begins to atrophy is the a: spleen b: thymus c: palatine tonsils d: bone marrow

B

Lymphatic vessels a: serve as sites for immune surveillance b: filter lymph c: transport leaked plasma proteins & fluids to the cardiovascular system d: are represented by vessels that resemble arteries, capallaries, and veins

C

The structural framework of lymphoid organs is? a: areolar connective tissue b: hematopoetic tissue c: reticular tissue d: adipose tissue

C

Cortex

. 1 of 2 distinct regions in a lymph node . contains follicles with germinal centers, heavy with dividing B-cells . dendritic cells nearly encapsulate follicles . deep cortex houses T-cells

Outer region with densely packed collections of lymphocytes called follicles and germinal centers

Cortex

Collections of lymphoid tissue (MALT) that gaurd mucosal surfaces include all of the following except a: appendix follicles b: the tonsils c: peyer's patches d: the thymus

D

Why do lymph nodes swell during an illness?

Large amounts of cellular debri accumulate and slow fluid flow through nodes

There are no lymphatic arteries. Why isn't this a problem?

Lymph is generated in the body tissues and only flows back toward the heart, so there is no need for arteries to carry lymph away from the heart

Lymphatic vessels through which lymph flows from the interstitial compartment of tissues to the point where it si returned to the blood stream

Lymphatic capillaries capture interstitial fluid ----> increased pressure forces open the valves & more interstitial fluid is collected by the lymphatic capillaries ----> lymphatic capillaries unite into lymphatic collecting vessels ----> lymphatic collecting vessels unite to form larger vessels called lymphatic trunks ----> lymphatic trunks merge to form the 2 largest vessels called right lymphatic duct and thoracic duct ----> right lymphatic duct drains lymph from the upper & arm right side of the head and thorax ----> thoracic trunk recieves lymph from the rest of the body and arises as a large sac called cisternae chyli ----> lymph is returned to main circulation at the junction of the subclavian vein & jugular vein on both sides of the body

Giant WBCs that destroy bacteria by phagocytosis

Macrophages

Central, innermost region of lymph node

Medulla

Why do people who have a splenectomy later have difficulty fighting infection?

The spleen is a site for lymphocyte proliferation and also cleans the blood of bacteria and viruses

Deep to sternum in mediastinum

Thymus

Where T lymphocytes become immunocompetent

Thymus

Ring of tissue around entrance to pharynx

Tonsils

(a) Which anatomical characteristic ensures that the flow of lymph through lymph node is slow? (b) Why is this desirable?

a. The anatomical characteristic that ensures slow passage of lymph through a lymph node is the fact that there are fewer efferent vessels draining the node than afferent vessels feeding it. b. This feature is desirable to allow time for the lymphocytes and macrophages to perform their protective functions.

Thoracic duct

arises as cisterna chyli , a dilated sac that drains the rest of the body

Trabeculae

connective tissue strands the extend inward and divide node into compartments

Plasma cells

daughter cells that secrete antibodies into the blood or other body fluids

Capsule

dense fibrous capsule that surrounds each lymph node, with a space underneath called subcapsular sinus

Right lymphatic duct

drains lymph from right upper limb and right side of head and thorax

Lymphatic vessels (lymphatics)

elaborate networks of drainage vessels that collect the excess protein - containing interstitial fluid and return it to the blood stream

Lymph

interstitial fluid once it enters the lymphatic vessels (lymph = clear water)

Lymph sinuses

lymphatic capillaries spanned by crisscrossing reticular fibers (subcapsular sinus & medullary sinus)

Most abundant cell type in lymph node

lymphocyte (B)

T cells (T lymphocytes)

manage immune response as T regulator cells and attack and destroy infected cells as T effector cells

Lymph capillaries

microscopic , minute lymphatic vessels that collect interstitial fluid from tissues

Macrophages

phagocytize foreign substances; and help activate T cells

Lymphatic collecting vessels

similar to veins except have thinner walls, with more internal valves and anastomose more frequently

B cell ( B lymphocytes)

when activated to a specific antigen produce plasma cells , which secrete antibodies that marl antigens for destruction by phagocytosis or other means

Compare the structure and functions of a lymph node to those of the spleen

. Lymph nodes are very small bean-shaped structures consisting of both a medulla and a cortex, which act as filters to cleanse lymph before it is allowed to reenter the blood. Each node is surrounded by a dense fibrous capsule from which connective tissue strands called trabeculae extend inward to divide the node into a number of compartments. The basic internal framework or stroma is an open network of reticular fibers that physically support lymphocytes and macrophages. The outer cortex contains densely packed spherical collections of lymphocytes called follicles, which frequently have lighter-staining centers called germinal centers. Cordlike extensions of the cortex, called medullary cords, invade the medulla. Macrophages are located throughout the node but are particularly abundant lining the sinuses of the medulla. . The spleen is the largest lymphoid organ. It functions to remove aged or defective blood cells, platelets, and pathogens from the blood and to store some of the breakdown products of RBCs or release them to the blood for processing by the liver. The spleen is surrounded by a fibrous capsule, and has trabeculae. It contains lymphocytes, macrophages, and huge numbers of erythrocytes. Venous sinuses and other regions that contain red blood cells and macrophages and process blood are referred to as red pulp, whereas areas composed mostly of lymphocytes suspended on reticular fibers are called white pulp. The white pulp clusters around small branches of the splenic artery within the organ and serves the immune functions of the organ.

White pulp

. around central arteries , mostly lymphocytes on reticular fibers . involved in immune functions

Peyer's patches

. clusters of lymphoid follicles, in wall of distal portion of small intestine . function is destroy bacteria preventing them from breaching intestinal wall & generate memory lymphocytes

3 functions of the lymphatic system

. filter and return interstitial fluid back to the circulatory system . immunity . transport fat and fat soluble substances

Lymphoid tissue

. houses and provides proliferation site for lymphocytes . surveillance vantage point for lymphocytes and macrophages . consists largely of reticular connective tissue (loose connective tissue)

Thymus

. important functions early in life . found in inferior neck, extends into mediastinum ; partially overlies heart . increases in size and most active during childhood, and stops growing during adolescence then gradually atrophies (shrinks) but still produces immunocompetent cells slowly (T&B cells) . Structure: > consists of thymic lobules with an outer cortex and inner medulla

Red pulp

. in venous sinuses and splenic cords . rich in RBCs and macrophages for disposal of worn out RBCs and bloodborne pathogens

organs / tissue of the lymphatic system

. include tissue & organs ---> diffuse lymphoid tissue and lymphoid follicles w/ germinal centers like tonsils, MALT, thymus, spleen, lymph nodes, & lymphatic vessels . NOTE : all lymphatic organs are made of reticular connective tissue with reticular fibers except the thymus

Spleen

. largest lymphoid organ, located on the left side of the abdominal cavity just beneath the diaphragm . Functions: > lymphocyte proliferation , immune surveillance and response > cleanses blood of aged cells & platelets, macrophages remove debris > recycle & store rbc breakdown products . structure: > 2 distinct areas called white pulp and red pulp

3 major components of the lymphatic system

. lymph . lymphatic vessels . lymphatic organs (tissues)

lymphatic vessels and pathways that lymph travels

. lymphatic capillaries . lymphatic collecting vessels . lymphatic trunks . lymphatic ducts . drain into junction of superior vena cava and internal jugular vein

Medulla

. mainly B-cells proliferating . medullary cords extend inward from cortex and contain B cells, T cells, and plasma cells . medullary lymph sinuses contain macrophages

5 mechanisms that help lymph flow in the lymphatic system

. milking action of skeletal muscles . pressure changes in the thoracic cavity . valves . pulsation of nearby arteries . smooth muscle contractions in lymphatic vessel walls

Lingual tonsils

. mucosa - associated lymphoid tissue . grouped at the base of tongue . function is to gather and remove pathogens in food and air

Pharyngeal tonsil

. mucosa - associated lymphoid tissue . in the posterior wall of nasopharynx . function is to gather and remove pathogens in food and air

Palatine tonsils

. mucosa - associated lymphoid tissue (MALT) . paired and at posterior end of oral cavity . largest tonsils and the ones most often infected . function is to gather and remove pathogens in food and air

MALT

. mucosal associated lymphoid tissues that are a set of distributed lymphoid tissues strategically located in mucous membranes throughout the body . functions to prevent pathogens from entering our bodies

Lymph nodes

. principal lymphoid organs of the body . embedded in connective tissue , in clusters along lymphatic vessels . near the body surface in inguinal, axillary, and cervical regions of the body . functions are filtering lymph and activating immune system . bean shaped and contain capsule, trabeculae , cortex, and medulla

Lymphoid organs and tissues

. provide structural basis of immune system . house phagocytic cell and lymphocytes . include the spleen, thymus, tonsils, other lymphoid tissues

5 function of the spleen

. site for lymphocyte production/initiates immune response . cleanses blood of old RBCs , platelets, bacteria, and viruses . stores products of RBC breakdown . produces RBCs in fetus . Stores platelets

Lymphoid follicles (nodules)

. solid spherical bodies of tightly packed lymphoid cells and reticular fibers that contain a germinal center of proliferating B cells . may form part of larger lymphoid organs . isolated aggregations of Peyer's patches and in appendix . function is provides proliferating site for lymphocytes as well as a surveillance vantage point for lymphocytes and macrophages

5 lymphoid organs other than lymph nodes

. spleen . thymus . tonsils . peyer's patches . appendix

Vessels that exits from node

Efferent vessel

Lymph nodes are designed to slow blood flow. How and why do they accomplish this?

Externally, lymph nodes possess more afferent than efferent vessels. Internally they are compartmentalized by trabeculae. The slowing of lymph flow allows debris, toxins, viruses, and bacteria to be more more completely filtered oud of the lymph fluid for it's return to main circulation

Area of lymph node where a vessel exits

Hilus

Area in lymph node where lymphocytes multiply

Germinal centers

Large isolated clusters of lymphoid tissue in small intestine

Peyer's patch

Prevent bacteria from everything through intestinal wall

Peyer's patch

Specialized large lymph capillaries in nodes the slows fluid movement

Sinusoids

Largest lymphoid organ; fist sized

Spleen

Located in left abdominal cavity just beneath diaphragm

Spleen