Chapter 21&22

In the lymphatic system, what is the role of red bone marrow?

It contains stem cells that develop into lymphocytes.

What is the primary source of the fluid that enters lymphatic capillaries to become lymph?

Interstitial fluid.

Where does the lymphatic system eventually empty its fluid?

Into venous blood.

Identify the three primary functions of the lymphatic system.

Draining interstitial fluid, transporting dietary fats, and facilitating immune responses.

Why are lipids transported through lymphatic vessels rather than directly into the bloodstream?

Lipids are too large to diffuse directly into blood capillaries.

How do T cells contribute to the immune response?

They recognize foreign cells and destroy them by rupturing their membranes.

How do B cells facilitate immunity against foreign substances?

They develop into plasma cells that produce specific antibodies.

Define 'resistance' in the context of human biology.

The ability to ward off damage or disease through body defenses.

What distinguishes non-specific resistance from specific resistance?

Non-specific resistance is innate at birth, while specific resistance develops in response to contact with particular invaders.

List three examples of mechanical or chemical barriers used in non-specific resistance.

Skin, mucous membranes, and the acidity of digestive juices.

Define 'susceptibility' regarding disease.

A lack of resistance to damage or disease.

How do lymphatic capillaries differ structurally from veins?

They have thinner walls and contain more valves than veins.

Name four anatomical regions or tissues where lymphatic capillaries are absent.

Avascular tissues, the central nervous system, parts of the spleen, and red bone marrow.

What mechanism allows fluid to enter a lymphatic capillary but prevents it from flowing back out?

One-way gaps that open when interstitial fluid pressure exceeds lymph pressure.

What are the specialized lymphatic capillaries in the small intestines called?

Lacteals.

What is 'chyle'?

Lymph that appears creamy white due to high lipid content from the small intestines.

The sequence of lymph flow begins at lymphatic capillaries and ends at _____.

Venous blood

Which lymphatic trunks are responsible for draining the lower limbs and kidneys?

The right and left lumbar trunks.

Which organs are drained by the intestinal trunk?

The stomach, intestines, pancreas, spleen, and part of the liver.

What areas do the bronchomediastinal trunks drain?

The thoracic wall, lung, and heart.

The right and left jugular trunks are responsible for draining lymph from the _____.

Head and neck

Identify the two main channels or ducts into which the lymphatic trunks empty.

The thoracic duct and the right lymphatic duct.

Where does the thoracic duct originate?

At the cisterna chyli.

Which body regions are drained by the thoracic duct?

The left side of the head, neck, chest, and arm, plus the entire body below the ribs.

Into which specific blood vessel does the thoracic duct empty?

The left subclavian vein.

What areas of the body are drained by the right lymphatic duct?

The upper right side of the body, including the right head, neck, arm, and thorax.

Into which specific blood vessel does the right lymphatic duct empty?

The right subclavian vein.

Define 'lymphedema'.

An accumulation of interstitial fluid caused by interference with lymphatic drainage.

What is the extreme case of lymphedema, often caused by parasitic worms, known as?

Elephantiasis.

Approximately how much interstitial fluid is absorbed by the lymphatic vessels daily?

3 liters

Why is lymph generally lower in protein concentration compared to blood plasma?

Large plasma proteins cannot easily diffuse out of blood capillaries into the interstitial space.

Which two physiological 'pumps' assist the movement of lymph through vessels?

Skeletal muscle pumps and respiratory pumps.

Formula: Net Filtration Pressure (NFP) in capillaries

NFP = (BHP + IFOP) - (BCOP + IFHP)

At the arterial end of a capillary, what is the typical result of the net filtration pressure (10 mmHg)

Net filtration of fluid out of the capillary.

At the venous end of a capillary, what is the typical result of the net filtration pressure (-9mmHg)?

Net reabsorption of fluid into the capillary.

What occurs in primary lymphatic organs?

Stem cells divide and develop into mature B cells or T cells.

Identify the two primary lymphatic organs.

Red bone marrow and the thymus gland.

What distinguishes secondary lymphatic organs, like the spleen, from lymphatic nodules?

Secondary organs are surrounded by a connective tissue capsule, while nodules are not.

Where is the thymus gland located?

In the mediastinum between the sternum and the aorta.

How does the size of the thymus gland typically change with age?

It is large in infants, peaks at puberty, and decreases in size as one gets older.

What is the structural function of trabeculae in a lymph node?

They divide the node into compartments and provide internal support.

In a lymph node, what occurs within the germinal centers of the outer cortex?

B cells mature and develop into plasma cells.

Identify the components of the lymph node stroma.

Capsule, trabeculae, reticular fibers, and fibroblasts.

Which cells in the lymph node medulla are responsible for phagocytizing foreign substances?

Macrophages.

Where is the spleen located in the human body?

On the left side of the body between the stomach and the diaphragm.

In the spleen, what comprises the 'white pulp'?

Lymphatic tissue consisting of lymphocytes and macrophages surrounding central arteries.

What are the primary functions of the spleen's red pulp?

Removing worn-out blood cells via macrophages and storing large amounts of platelets.

What is the consequence of a splenectomy regarding a patient's health?

The patient becomes more prone to infections.

What does the acronym MALT stand for?

Mucosa-associated lymphoid tissue.

What is the primary function of MALT in the gastrointestinal and respiratory tracts?

To protect against invasion by inhaled or ingested foreign substances.

Which tonsils are most commonly affected by chronic tonsillitis?

Palatine tonsils.

Identify the five major categories of pathogenic agents.

Bacteria, viruses, fungi, protozoans, and multicellular parasites.

Into what type of cell do monocytes transform when they enter body tissues?

Macrophages.

What are the three types of granulocytes involved in the immune system?

Neutrophils, eosinophils, and basophils.

How do interferons protect the body from viral spread?

They stimulate neighboring cells to produce antiviral proteins.

What is the role of the complement system in immunity?

It enhances (complements) specific immune, allergic, and inflammatory responses.

Define 'immunological surveillance'.

The constant monitoring of normal tissues by Natural Killer (NK) cells to destroy abnormal cells.

How do Natural Killer (NK) cells destroy abnormal or cancer cells?

They secrete proteins that destroy the target cell's membrane.

How does sebum provide chemical protection for the skin?

It inhibits the growth of certain bacteria.

What is lysozyme and where is it found?

An antimicrobial substance found in perspiration, tears, saliva, and nasal secretions.

How does gastric juice contribute to non-specific resistance?

It uses strong acidity to destroy bacteria and toxins in the stomach.

In the process of phagocytosis, what is the primary action taken against pathogens?

Engulfing and digesting cellular debris and microorganisms.

Which antimicrobial proteins inhibit bacterial growth by reducing available iron?

Transferrins.

Where are Peyer's patches located?

In the ileum of the small intestine.

Which duct drains lymph from the anterior part of the diaphragm and the left side of the heart?

The left bronchomediastinal trunk (emptying into the thoracic duct).