Decks (Anatomic-sciences) 2016-2017

Question 1

Which of the following structures carry lymph into the node’s subcapsuiar sinus, through the cortical sinus and into the superficial cortex and paracortex?
* efferent lymphatic vessels
* afferent lymphatic vessels
* both afferent and efferent lymphatic vessels
* neither afferent or efferent lymphatic vessels

Answer 1

• afferent lymphatic vessels
  Lymph nodes are small oval bodies enclosed in fibrous capsules. Lymph nodes contain phagocytic cortical tissue (reticular tissue) adapted to filter lymph. Specialized bands of connective tissue, called trabeculae, divide the lymph node.
  Afferent lymphatic vessels carry lymph into the node’s subcapsular sinus, through the cortical sinus and into the superficial cortex and paracortex. Conversely, the lymph may travel directly from the cortical sinus into the medullary sinus. It is primarily in these cortices and the medullary sinus that the lymph is cleansed by macrophages, and antigens are presented and processed by lymphocytes, and plasma cells. The filtered lymph leaves the node through the efferent lymphatic vessels, which merge through the concave hilum and transport the lymph into efferent collecting vessels, which converge into larger vessels called lymph trunks (there are five major lymph trunks in the body). The thoracic duct receives lymph from three out of the four quadrants of the body; both lower quadrants and the upper left quadrant. The right lymphatic duct receives lymph only from the upper right quadrant.
  Note: The thoracic duct receives lymph from three out of the four quadrants of the body; both lower quadrants and the upper left quadrant. The right
  lym phatic duct receives lymph only from the upper right quadrant.
  Important:
  1. The afferent lymphatic vessels enter on the convex surface of the node.
  2. There are fewer efferent vessels than afferent vessels associated with a node.
  3. The spleen, thymus, palatine, and pharyngeal tonsils do not have numerous afferent vessels entering them as do lymph nodes.
  4. The paracortex is dominated by T-cells

Question 2

Which of the following vessels are characterized by the presence of valves?
* arterioles only
* capillaries only
* sinusoids only
* veins only
* lymphatics only
* lymphatics and capillaries
* lymphatics and veins

Answer 2

• lymphatics and veins
  Primary lymphatic organs are responsible for the generation and selection of lymphocytes. These are the thymus and bone marrow. Secondary lymphatic organs include the tonsils, spleen, lymph nodes, appendix, which are responsible for the filtering component. There are also areas of diffuse lymphoid tissue throughout the body including MALT, GALT, and BALT (mucosa-, gut-, and bronchus-associated
  lymphoid tissue, respectively). GALT includes the tonsils and Peyer’s patches. The common component to all lymphatic tissues is the presence of lymphocytes.
  Functions of the lymphatic system:
• Returns tissue fluid to the bloodstream: when this fluid enters lymph capillaries, it is called lymph. Lymph is returned to the venous system via two large lymph
  ducts, the thoracic duct and the right lymphatic duct
• Transports absorbed fats: within the villi in the small intestine, lymph capillaries, called lacteals, transport the products of fat absorption away from the Gl tract and eventually into the circulatory system through the thoracic duct
• Provides immunological defenses against disease-causing agents: lymph filters through lymph nodes, which filter out microorganisms (such as bacteria) and
  foreign substances. Lymph nodes have also been shown to trap cancerous cells in the body.
  1. Lymph contains a liquid portion that resembles blood plasma, as well as white blood cells (mostly lymphocytes) and a few red blood cells.
  2. Lymph is absorbed from the tissue spaces by the lymphatic capillaries (which is a system of closed tubes) and eventually returned to the venous circulation by the lymphatic vesse’s, after lymph flows through the filtering system (lymph nodes).
  3. In the upper limb, a hallmark of lymphatic vessels is that they follow the veins.
  4. The lymphatic system does not have a central pump to move lymph throughout the body. “Instead, the lymphatic system depends on the contractions of skeletal muscles, the presence of valves in lymphatic
  vessels (similar to those in veins), breathing, and simple gravity to move fluid throughout the body.”

Question 3

T cells are produced in the__ and mature in the__
* liver, thymus
* bone marrow, liver
* bone marrow, thymus
* lymph nodes, thymus

Answer 3

• bone marrow, thymus
  The thymus is a bilobed lymphoid organ positioned in the superior mediastinum in adults, with the inferior part contained in the anterior mediastinum of children; it does not contain lymph nodules or vessels. The main function of the thymus is to potentiate immunocompetent T cells from their immunoincompetent precursors. Additionally, self-recognizing T cells are destroyed in the thymus. The thymus is relatively large in newborns, continues to grow until puberty, at which point it undergoes involution, being replaced by adipose tissue. Note: In the adult thymus, the blood supply is isolated from the parenchyma (which is the functioning portion of the gland as distinguished from the connective tissue or stroma). This is sometimes referred to as the blood
  thymus barrier. In the child thymus, the blood supply is not isolated from the parenchyma.
• Hassall’s corpuscles: are structures found in the medulla of the human thymus, formed from eosinophilic type VI epithelial reticular cells arranged concentrically. The function of Hassall’s corpuscles is currently unclear.
• Digeorge syndrome: is a congenital disease that is characterized by absent or underdeveloped thymus and parathyroid glands. It’s typically caused by a deletion on the chromosome numbered 22. Patients suffering from Digeorge have profound immunodeficiency due to a lack of T cells. No other immune cell populations are affected.
  The spleen is formed by reticular and lymphatic tissue and is the largest lymph organ. The spleen lies between the fundus of the stomach and the diaphragm. The spleen is purplish in color and
  varies in size in different individuals. The spleen is slightly oval in shape with the hilum on the lower medial border. The spleen is entirely covered by peritoneum, except at the hilum. It is enclosed in a fibroelastic capsule that dips into the organ, forming trabeculae, but trabeculae DO NOT divide the spleen into lobes/lobules. The spleen also has no distinct cortex or medulla.
  The cellular material, consisting of lymphocytes and macrophages, is called splenic pulp, and it lies between the trabeculae. Supplied by the splenic artery, a branch of the celiac artery.
  The spleen is the largest single mass of lymphoid tissue in the body. The spleen can be considered as two organs in one; it filters the blood and removes abnormal cells (such as old and defective red blood cells), and it makes disease-fighting components of the immune system (including antibodies and lymphocytes). The body of the spleen appears red and pulpy, surrounded by a tough capsule. The red pulp consists of blood vessels (splenic sinusoids) interwoven with connective tissue (splenic cords). The red pulp filters the blood and removes old and defective blood cells. It, along with the liver, are site of erythropoiesis (blood formation) in the fetus and infant. The white pulp is inside the red pulp, and consists of little lumps of lymphoid tissue. Antibodies are made inside the white pulp

Question 4

Posterior 1/3 of the tongue drains into:
* facial nodes
* occipital nodes
* submandibular nodes
* deep cervical nodes
* submental nodes
* jugulodigastric nodes

Answer 4

• deep cervical nodes
  The deep cervical lymph nodes are located along the length of the internal jugular vein on each side of the neck, deep to the sternocleidomastoid muscle. The deep cervical nodes extend from the base of the skull to the root of the neck, adjacent to the pharynx, esophagus, and trachea. The deep cervical nodes are further classified as to their relationship to the sternocleidomastoid muscle as being superior or
  inferior.
  The deep cervical lymph nodes are responsible for the drainage of most of the circular chain of nodes, and receive direct efferents from the salivary and thyroid glands, the posterior 1/3 of the tongue, the tonsils, the nose, the pharynx, and the larynx. All these vessels join together to form the jugular lymph trunk. This vessel drains into either the thoracic duct on the left or the right lymphatic duct on the
  right, or it independently drains into the internal jugular, subclavian, or brachiocephalic veins.
  Some regional groups of lymph nodes:
• Parotid lymph nodes - receive lymph from a strip of scalp above the parotid salivary gland, from the anterior wall of the external auditory meatus, and from the lateral parts of the eyelids and middle ear. The efferent lymph vessels drain into the deep cervical nodes.
• Submandibular lymph nodes - located between the submandibular gland and the mandible; receive lymph from the front of the scalp, the nose, and adjacent cheek; the upper lip and lower lip (except the center part); the paranasal sinuses; the maxillary and mandibular teeth (except the mandibular incisors); the anterior two-thirds of the tongue (except the tip); the floor of the mouth and vestibule; and the gingiva. The efferent lymph vessels drain into the deep cervical nodes.
• Submental lymph nodes - located behind the chin and on the mylohyoid muscle; receive lymph from the tip of the tongue, the floor of the mouth beneath
  the tip of the tongue, the mandibular incisor teeth and associated gingiva, the center part of the lower lip, and the skin over the chin. The efferent lymph vessels drain into the submandibular and deep cervical nodes

Question 5

When antigen recognition occurs by a lymphocyte, B cells are activated and migrate to which area of the lymph node?
* inner medullary region
* medullary cords
* medullary sinuses
* germinal centers

Answer 5

• germinal centers
  Lymph nodes are small, round specialized dilations of lymphatic tissue that are permeated by lymphatic channels. Their function is primarily to act as filters. They help to remove and destroy antigens that circulate in the blood and lymph. For this purpose, lymph nodes contain a lot of macrophages. Lymphoid tissue in the nodes also produces antibodies and stores lymphocytes. Note: The nodes generally occur
  in clusters along the connecting lymphatic vessels particularly in the armpits, the groin, the lower abdomen, and the sides of the neck.Each lymph node is enclosed in a fibrous capsule with internal trabeculae (connective tissue) supporting lymphoid tissue and lymph sinuses.
  The node consists of:
• Outer (superficial) cortical region: contains separate masses of lymphoid tissue called lymphoid follicles. Prim ary follicles are not responding to antigen. They
  stain uniformly. Secondary follicles contain predominately B cells (lightly staining germinal centers); they are active follicles responding to antigen and are a source of lymphocytes.
• Paracortical region: is dominated by T cells. B cells enter the node from the blood
  in this region and quickly migrate to the superficial cortex.
• Inner medullary region: lymphoid tissue here is arranged in medullary cords, which are a source of plasma cells (they secrete antibodies). Also contains medullary sinuses. Lymph nodes can be classified as primary or secondary. Lymph from a particular region drains into a primary node or regional node. Primary nodes, in turn, drain into a secondary node or central node.
  Definitions:
• Germinal centers: are sites within lymph nodes (also within lymph nodules in peripheral lymph tissues) where mature B lymphocytes rapidly proliferate, differentiate, mutate their antibodies (through somatic hypermutation), and class
  switch their antibodies during a normal immune response to an infection.
• Medullary cord is a portion of the medulla of the lymph node which contains lymphatic tissue and project into the medullary sinus. B cells and plasma cells are the main cell types found in the medullary cords

Question 6

The lymph from the lower extremities drains into the
* left internal jugular vein
* left subclavian vein
* junction of the left internal jugular and subclavian veins
* superior vena cava
* junction of the right internal jugular and subclavian veins

Answer 6

• junction of the left internal jugular and subclavian veins
  The thoracic duct is the main duct of the lymphatic system and is located in the posterior mediastinum. It begins below in the abdomen as a dilated sac, the cisterna chyli (at the level of the T12 vertebra) and ascends through the thoracic cavity in front of the spinal column (between the descending thoracic
  aorta [to its left] and the azygos vein [to its right]). It is the common trunk of all the lymphatic vessels of the body, and drains the lymph from the majority of the body (legs, abdomen, left side of head, left arm, and left thorax). Note: The right lymphatic duct drains much less of the body lymph (only the lymph from
  the right arm, right thorax, and right side of the head).
  Im portant: The thoracic duct is approximately 40 cm long and transports lymph from the entire lower half of the body and left upper quadrant. It empties
  into the left venous angle between the left internal jugular vein and the left subclavian vein (which is actually the beginning of the left brachiocephalic
  vein). The right lymphatic duct is approximately 1 cm long and collects lymph from the right upper quadrant of the body and empties into the right
  venous angle at the junction of the right internal jugular vein with the right subclavian vein (which is actually the beginning of the right brachiocephalic
  vein).
  1. The thoracic duct ascends through the aortic opening in the diaphragm, on the right side of the descending aorta.
  2. The thoracic duct contains valves and ascends between the aorta and the azygos vein in the thorax.
  3. The intercostal lymphatic vessels transport lymph from the left and right intercostal spaces to the thoracic duct.
  4. Mammary glands drain lymph into axillary lymph nodes.
  5. Kidneys drain lymph into lumbar lymph nodes.
  6. Lungs and trachea drain lymph into hilar lymph nodes (which are located in the hilum of the lung)

Question 7

Which of the following is NOT a function of the spleen?
* removal of old or defective blood cells from blood
* forming crypts that trap bacteria
* storage of blood platelets
* storage of iron

Answer 7

• forming crypts that trap bacteria
  The spleen lies in the left hypochondriac region of the abdominal cavity between the fundus of stomach and the diaphragm. The spleen is an ovoid organ roughly the size of a fist. The spleen contains white and red pulp. The white pulp contains compact masses of lymphocytes surrounding branches of the splenic artery. The red pulp consists of a network of blood-filled sinusoids, along with lymphocytes, macrophages, plasma cells, and monocytes (phagocytic white blood cells).
  There are three major functions of the spleen, and these are handled by three different tissues within the spleen:
• Reticuloendothelial tissue: concerned with phagocytosis of erythrocytes and cell debris from the bloodstream. This same tissue may produce foci of hemopoiesis when RBCs are needed.
• Venous sinusoids: along with the power of the spleen to contract, provides a method for expelling the contained blood to meet increased circulatory demands
• White pulp: provides lymphocytes and a source of plasma cells and hence antibodies for the cellular and humoral specific immune defenses composed of nodules containing Malpighian corpuscles Blood enters the spleen at the hilum through the splenic artery and is drained by the splenic vein, which joins the superior mesenteric vein to form the hepatic portal vein to the liver. The nerves to the spleen accompany the splenic artery and are derived from the celiac plexus. Note: Like the thymus, the spleen possesses only efferent lymphatic vessels.
  Remember: Although the spleen does not develop from the primitive gut, as do the lungs, liver, pancreas, gallbladder, stomach, esophagus, and intestines, it shares the blood supply of the foregut which is supplied by the celiac trunk. The spleen develops
  from mesenchymal cells of the mesentery attached to the primitive stomach.
  1. Infectious mononucleosis: is a common, acute, usually self-limited infectious disease caused by the EBV, characterized by fever, membranous pharyngitis, lymph node and splenic enlargement.
  2. Asplenia: refers to the absence of normal spleen function and is associated with some serious infection risks, especially encapsulated bacteria such as streptococcus pneumoniae, haemophilus infuenzae and neisseria meningitidis.

Question 8

Which of the following tonsil(s) is/are covered by nonkeratinized stratified squamous epithelium?
Select all that apply.
* lingual tonsils only
* pharyngeal tonsil only
* palatine tonsils only
* pharyngeal and palatine tonsils
* lingual and palatine tonsils
* all of the above

Answer 8

• lingual and palatine tonsils
  The tonsils are lymphatic organs that lie under the surface lining of the mouth and throat. They
  are considered part of the secondary immune system. They sit in the respiratory and alimentary tracts in position to be exposed to inspired or ingested antigens from air or food.
  When sufficient antigen is present, this stimulates the B cells in the germinal zone of the lymphoid follicle to differentiate and produce antibodies. The tonsils are involved in the production of mostly secretory IgA, which is transported to the surface, providing local immune protection. There are three sets of tonsils, named according to their position.
• The adenoids (pharyngeal tonsil) are located on the posterior wall of the nasopharynx. They
  are at their peak of development during childhood. They are surrounded partly by connective
  tissue and partly by ciliated pseudostratified columnar epithelium (respiratory epithelium). They contain no crypts.
• The palatine tonsils are located on the posterolateral walls of the throat, one on each side.
  They reach their maximum size during early childhood, but after puberty diminish considerably
  in size. These are the tonsils that are noticeably enlarged when a person suffers from a “sore throat.” They contain many crypts, lymphoid follicles, but no sinuses. The palatine tonsils are surrounded partly by connective tissue and partly by nonkeratinized stratified squamous epithelium. Important point: The best way to distinguish the palatine tonsil from the pharyngeal tonsil on the histologic level is the type of epithelium associated with it.
• The lingual tonsils are smaller and more numerous. They are a collection of lymphoid follicles on the posterior portion of the dorsum of the tongue. Each has a single crypt. They are surrounded by nonkeratinized stratified squamous epithelium. Note: The three groups of tonsils are often referred to as Waldeyer’s Ring or the Tonsillar Ring.
  Remember: Peyer’s patches are similar in structure and function to the tonsils (Peyer’s patches form “intestinal tonsils”). Located in the small intestine (specifically, the ileum), they serve to destroy the abundant bacteria, which would otherwise thrive in the moist environment of the intestine. Note: Peyer’s patches and tonsils are considered subepithelial and non- encapsulated lymphoid tissues.
  Tonsillectomy: is a surgical procedure in which the tonsils are removed from either side of the
  tonsillar fossa. The procedure is performed in response to cases of repeated occurrence of
  acute tonsillitis or adenoiditis, obstructive sleep apnea, nasal airway obstruction, diptheria carrier
  state, snoring, or peritonsillar abscess. For children, the adenoids are removed at the same time,
  a procedure called adenoidectomy

Question 9

In which of the following locations would one most likely find yellow bone marrow in an adult?
* diaphysis of femur
* epiphysis of humerus
* ribs
* cranial bones
* vertebrae

Answer 9

• diaphysis of femur
  ** Yellow marrow is found in the hollow center of the diaphysis (the long shaft of the bone) known as the medullary cavity. The bones are not solid structures. Cavities in the cranial bones, vertebrae, ribs, sternum, and the ends of long bones contain red bone marrow. This blood-forming tissue produces erythrocytes, leukocytes, and thrombocytes within bones by a process called hemopoiesis.
  1. Before birth, the formed elements are also produced in a number of other locations, including the yolk sac, liver, spleen, and lymph
  nodes.
  2. Erythropoiesis refers specifically to the production of erythrocytes. The red bone marrow contains precursor cells called hemocytoblasts (multipotent stem cells) that give rise to all of the formed elements of the
  blood. The hemocytoblasts give rise to various committed progenitor cells, which give rise to the different types of formed elements. For example, the erythrocytes develop from proerythroblasts; the platelets develop from large cells called m egakaryocytes.
  When a child is 7 years of age, yellow marrow begins to appear in the distal bones of the limbs. This replacement of marrow gradually moves proximally, so that by the time the person becomes an adult, the red marrow is restricted to the bones of the skull, the vertebral column, the thoracic cage, the girdle
  bones, and the head of the humerus and femur.
  **At birth, all bone marrow is red.