Lymphatic & Immune System Flashcards (combined; has duplicates)

What is the relationship between the lymphatic system and the cardiovascular system?

The lymphatic system is closely associated with the cardiovascular system; it collects excess fluid that leaks from cardiovascular capillaries due to high pressure and returns it to the bloodstream.

Why does fluid leak out of cardiovascular capillaries?

High pressure in the cardiovascular system forces fluid out of the capillaries into the surrounding tissues (interstitial spaces).

What does the leaked fluid from capillaries carry to body cells?

The leaked fluid carries nutrients from the arterial end of capillaries and delivers oxygen to tissues.

What happens to most of the leaked fluid at the venous end of capillaries?

Most of the leaked fluid is reabsorbed back into the bloodstream at the venous end of capillaries.

What problem occurs if not all leaked fluid is reabsorbed?

If excess fluid is not reabsorbed, it accumulates in tissue spaces, leading to edema (swelling).

How does the lymphatic system solve the problem of excess fluid leakage?

The lymphatic system collects the excess leaked fluid through lymphatic capillaries and returns it to the bloodstream via lymphatic vessels and ducts.

Approximately how many liters of fluid per day cannot return directly to the cardiovascular system?

About 3 liters of fluid per day leak from the cardiovascular system and must be collected by the lymphatic system.

What are the three major functions of the lymphatic system?

1) Fluid collection and return to the bloodstream, 2) Transport of large fat molecules (long-chain fatty acids) from the intestines, and 3) Immune defense.

What specific nutrients does the lymphatic system transport from the intestines?

Long-chain fatty acids absorbed from the digestive tract.

Why is the lymphatic system important for immune defense?

It plays a cornerstone role in immunity by filtering harmful substances through lymph nodes and housing lymphocytes that defend the body against pathogens.

What type of vessels are lymphatic capillaries?

Dead-end vessels (cul-de-sacs) --- the tiniest vessels in the lymphatic system that pick up leaked fluid from surrounding tissues.

Where are lymphatic capillaries located relative to blood capillaries?

Lymphatic capillaries run between blood capillaries; they are separate from but positioned near blood capillaries.

What type of epithelium lines lymphatic capillaries?

Simple squamous epithelium (flattened cells).

How do lymphatic capillaries create a one-way valve system?

The edges of the simple squamous epithelial cells overlap each other, allowing fluid to flow in from tissue spaces but preventing it from flowing back out.

What structures anchor the overlapping cells of lymphatic capillaries?

Tiny microscopic collagen filaments (anchoring filaments) attach to the surrounding connective tissue matrix, maintaining the one-way valve structure.

What is the fluid called before it enters a lymphatic capillary?

Tissue fluid (interstitial fluid).

What is the composition of lymph?

A clear, pale fluid containing water, electrolytes, proteins, and immune cells (primarily lymphocytes).

Can lymphatic capillaries absorb large molecules like proteins and fats?

Yes, due to their permeability, lymphatic capillaries can absorb larger molecules such as proteins and fats that cannot enter blood capillaries.

How do lymphatic capillaries progress to larger vessels?

Multiple capillaries merge together, increasing in diameter, forming lymphatic vessels, and then even larger lymphatic ducts.

What are lymphatic ducts?

The largest lymphatic vessels in the system, formed by the progressive merging and enlargement of lymphatic vessels.

Where do lymph nodes appear along the lymphatic vessels?

In specific regions including the axillary (armpit), cervical (neck), and inguinal (groin) regions, among others.

What are lacteals?

Special lymphatic capillaries that drain the wall of the intestine and absorb long-chain fatty acids from digested food.

Why do long-chain fatty acids need lacteals for transport?

Long-chain fatty acids cannot pass through blood capillaries in the intestinal wall, so they must be absorbed by lacteals instead.

What happens to short and medium-chain fatty acids in the intestine?

They can pass directly through the intestinal wall into blood capillaries without needing lacteals.

What is chyle?

The milky-white fluid within lacteals that contains lymph plus long-chain fatty acids (fatty molecules), giving it a milky appearance.

Why does lymph from the intestines appear milky?

Because it contains emulsified fats (long-chain fatty acids) absorbed from digested food, forming chyle.

What are the three layers (tunics) of a lymphatic vessel?

1) Tunica intima (innermost, simple squamous epithelium with valves), 2) Tunica media (smooth muscle), 3) Tunica externa/adventitia (connective tissue).

What is the function of the tunica media in lymphatic vessels?

It contains smooth muscle, allowing the vessel to contract and help move lymph.

Do lymphatic vessels have valves? What is their purpose?

Yes, lymphatic vessels have valves throughout their length to prevent backflow and ensure one-way movement of lymph toward the heart.

How are lymphatic vessels structurally similar to veins?

Both have three layers (tunics) and contain valves to prevent backflow.

What is the thoracic duct also called?

The left lymphatic duct; it is the largest lymphatic vessel in the body.

What areas of the body does the thoracic duct drain?

The entire left side of the body, the entire lower body (below the diaphragm), and the right side EXCEPT the right upper quadrant.

Where does the thoracic duct drain into?

The junction of the left subclavian vein and the left internal jugular vein.

What area does the right lymphatic duct drain?

The right side of the face, right side of the neck, the right upper limb (arm), and the right thorax (upper chest).

Which duct drains the larger portion of the body --- the thoracic duct or the right lymphatic duct?

The thoracic duct drains the majority of the body; the right lymphatic duct only drains a small area (right upper quadrant).

Why might a patient develop edema in the arm after breast cancer surgery?

If axillary lymph nodes are removed during a mastectomy, the lymphatic drainage pathway for that arm is disrupted, causing fluid to accumulate and resulting in edema.

What is the approximate probability of developing arm edema after axillary lymph node removal?

There is a 99% possibility the patient will develop swelling (edema) in that arm.

What is lymphedema?

Swelling caused by fluid accumulation due to disrupted or dysfunctional lymphatic drainage.

Does the lymphatic system have a pump like the heart?

No

Lymph flow is maintained by several other factors.

How do respiratory movements maintain lymph flow?

When the diaphragm moves down during breathing, abdominal pressure increases and thoracic pressure decreases, creating a pressure gradient that moves lymph from the abdomen to the thorax.

How do arterial pulsations help move lymph?

Superficial lymphatic vessels run near veins and deeper ones near arteries; arterial pulsations squeeze adjacent lymphatic vessels, pushing lymph forward.

How does the muscle pump help lymph flow?

Skeletal muscle contractions squeeze lymphatic vessels (similar to venous return), and valves ensure lymph moves in the correct direction.

How does osmotic pressure from absorbed nutrients maintain lymph flow?

When lacteals absorb long-chain fatty acids (large particles), osmotic pressure in the lymph increases, drawing more fluid from tissue spaces into the lymphatic vessels.

Name the five factors that maintain lymph flow.

1) Respiratory movements, 2) Arterial pulsations, 3) Presence of valves, 4) Skeletal muscle contractions, 5) Osmotic pressure from absorbed nutrients.

Why are certain tissues and organs called 'lymphoid'?

Because the dominant cell type present in these structures is the lymphocyte.

Name the major lymphoid organs and tissues.

Lymph nodes, spleen, thymus, tonsils, and other lymphoid tissues (including the appendix).

What is the shape of a lymph node?

Bean-shaped structure with one concave (indented) side and one convex (rounded) side.

What is the capsule of a lymph node made of?

Dense connective tissue that protects the lymph node.

What are nodules in a lymph node?

Small compartments created when the capsule extends inward and divides the interior of the lymph node.

What is a germinal center in a lymph node?

The pale-colored center of each nodule where lymphocytes actively divide, proliferate, and mature.

What is the cortical area of a lymph node?

The darker region surrounding the germinal center, containing densely packed lymphocytes.

What cell types are found in lymph nodes?

Lymphocytes (B and T cells) and macrophages (derived from monocytes).

What type of connective tissue is found within lymph nodes?

Reticular connective tissue, which contains reticular fibers that form a supportive network.

How are lymph nodes named?

Based on their anatomical region --- e.g., cervical (neck), axillary (armpit), inguinal (groin).

Should you be able to feel (palpate) a normal lymph node?

No, normal lymph nodes are not palpable. If you can feel one, it indicates enlargement due to infection or immune activity.

What does an enlarged lymph node indicate?

It indicates the node is actively filtering harmful particles, fighting infection, or responding to disease.

What are afferent lymphatic vessels?

Vessels that bring lymph TO the lymph node; they attach to the convex (outer) surface.

How does lymph flow through a lymph node?

Lymph enters through multiple afferent vessels on the convex surface → flows through sinuses → gets filtered → exits through fewer efferent vessels at the hilum.

What are the two main functions of lymph nodes?

1) Maturation of lymphocytes (making them immunocompetent), 2) Conversion of monocytes into macrophages.

What do mature lymphocytes become in lymph nodes?

Some become plasma cells (producing antibodies), and others become cytotoxic cells (attacking infected or abnormal cells).

What are the types of sinuses in a lymph node?

Capsular sinuses (located under the capsule) and medullary sinuses (located in the medulla/central region).

What is the outer cortex of a lymph node?

The region containing follicles, which are sites of B-cell activation and proliferation.

What is lymphadenopathy?

A general term meaning enlarged lymph nodes (lymphaden- = lymph nodes, -pathy = disease/abnormality).

What is lymphadenitis?

Inflammation of lymph nodes (lymphaden- = lymph nodes, -itis = inflammation), resulting in enlarged, tender lymph nodes.

Where is the spleen located?

In the left upper quadrant of the abdomen, positioned between ribs 9--11.

What clinical concern arises with fractures to ribs 9--11 on the left side?

Possible splenic injury (laceration), since the spleen is located behind those ribs.

What are the anatomical relations of the spleen?

Above: diaphragm; In front of: left kidney; Behind: stomach (fundus) and colon (splenic flexure).

What are the dimensions of the spleen?

12 cm × 7 cm × 4 cm.

Why is the spleen dark red in color?

Due to its extensive blood supply.

What is the blood supply to the spleen?

The splenic artery, a branch from the celiac trunk (from the aorta), provides a rich blood supply.

What is a splenectomy?

Surgical removal of the spleen; can be performed via open or laparoscopic surgery, often indicated when the spleen is lacerated beyond repair.

What are the two main tissue types in the spleen?

White pulp (central lymphoid tissue containing lymphocytes) and red pulp (surrounding area filled with red blood cells).

Is the spleen the largest lymphoid organ?

Yes

Name the functions of the spleen.

1) Hematopoiesis (RBC production), 2) Blood reservoir/filtration, 3) Lymphoid functions (lymphocyte maturation, infection fighting, monocyte-to-macrophage conversion), 4) Destruction of aged RBCs.

What is splenomegaly and how does it cause anemia?

An enlarged spleen that pulls more blood and RBCs into storage, potentially causing anemia by reducing circulating RBC counts.

How does the spleen recycle old red blood cells?

It breaks down aged, worn-out red blood cells and recycles the iron from hemoglobin.

Where is the thymus gland located?

In the mediastinum (central chest cavity), behind the sternum. It consists of two lobes.

How does the thymus change with age?

It is present and increases in size throughout childhood, then begins to atrophy (shrink) at the onset of puberty.

At what age is the thymus largest?

In younger children (around ages 5--12), compared to teenagers or adults.

What are Hassall's corpuscles?

Characteristic concentric, layered structures found within the thymus gland.

What is the primary function of the thymus?

Maturation and education of T-lymphocytes (T-cells), training them to distinguish self from non-self antigens.

What hormone does the thymus produce?

Thymosin, which stimulates the development of T-cells.

What is the internal structure of the thymus?

Divided into lobules, each containing a cortex and medulla, with spaces between lobules.

What are the three types of tonsils and their locations?

1) Palatine tonsils -- either side of the throat, 2) Pharyngeal tonsil (adenoid) -- posterior nasopharynx, 3) Lingual tonsils -- base of the tongue.

What is a tonsillectomy?

Surgical removal of the palatine tonsils.

What is an adenoidectomy?

Surgical removal of the pharyngeal tonsil (adenoid).

What is T&A?

Tonsillectomy and adenoidectomy performed together.

What is the function of the tonsils?

First line of defense against inhaled or ingested pathogens

part of mucosa-associated lymphoid tissue (MALT).

Where do T-lymphocytes originate and where do they mature?

They originate in bone marrow and mature in the thymus gland.

Name and describe the four types of T-cells.

1) Cytotoxic T-cells -- directly attack/lyse infected, cancer, or foreign cells; 2) Helper T-cells -- activate B-cells and other T-cells, coordinate responses; 3) Suppressor T-cells -- regulate/suppress immune responses; 4) Memory T-cells -- remember past infections for faster future response.

What type of immunity do T-cells mediate?

Cell-mediated immunity (T-cell mediated immunity)

How do T-cells attack?

they attack antigens through direct cell-to-cell contact without producing antibodies.

How are T-cells activated?

When they recognize specific antigens presented by antigen-presenting cells (APCs).

What is clonal expansion?

After activation, T-cells rapidly divide, producing thousands of identical cells to fight an infection.

What percentage of lymphocytes are T-cells?

T-cells make up 70--80% of lymphocytes.

Where do B-lymphocytes originate and mature?

B-cells both originate and mature in bone marrow.

What does 'humoral' mean in humoral immunity?

'Humoral' refers to body fluids; antibodies are found in blood and other bodily fluids.

What do activated B-cells differentiate into?

Plasma cells (which secrete antibodies) and memory B-cells (for faster future responses).

What are the five types of immunoglobulins (antibodies)?

IgA, IgD, IgE, IgG, and IgM.

What is the function and location of IgA?

Found in mucous membranes, saliva, tears, and breast milk; provides local/mucosal immunity and prevents pathogen adherence.