LYMPHATIC SYSTEM[PHYSIOLOGY TESTS ONLY]
PERFUSION OF TISSUES AND THE ORIGIN OF LYMPH


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Blood Flow regulation in tissues (Marieb 6th Ed pp 736 - 740)

Specific circulations (Marieb 6th Ed pp 742 - 766)


Formation of Extracellular fluid

Arterial pressure relayed into Capillary bed :
Arterial side: Hydrostatic pressure ~ 35mmHg
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............................................Fenestrated Capillaries-- Plasma seeps through capillaries - Fluid that Bathe cells = Extracellular fluid
................................................................................................................................... Fluid that fills other space = Interstitial fluid

......................This results in increased hydrostatic pressure in the tissues and Hydrostatic pressure inside capillary drops
......................Loss of fluid from capillaries increases colloid osmotic pressure of blood
Venous side : Hydrostatic pressure ~ 17 mmHg

Some fluid from tissues re-enters capillary

What is Tissue fluid ?

Extracellular fluid + Interstitial fluid

What is Lymph ?


Below: Top - a blood capillary ............ Bottom - tip of a lymph capillary
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Once tissue fluid enters the lymph capillaries the fluid is then known as lymph.
In the digestive system special lymphatic capillaries, lacteals , absorb fats : content = chyle
Lymph capillaries unite to form lymphatic collecting vessels - structure similar to veins

flow is one-way - aided by valves in the vessels
Collecting vessels —> larger collecting vessels ----> lymphatic trunks:
.....................................................................................lumbar , bronchomediastinal, subclavian , jugular trunks
.....................................................................................intestinal trunk on its own - containing chyle
Trunks ----> right lymphatic duct - right arm, right side of head and R section of thorax

..................thoracic duct - much larger = remainder of trunk/rest of body

Lymph Flow

No pump - dependent on pressures in tissue

muscle action - physical activity

One-way valves

Contraction of larger trunks and ducts

Lymph Vessels merge (afferent vessels) at lymph nodes and divert from there again fewer in number and vessels exiting (efferent) are larger

LOCATION OF LYMPH VESSELS AND NODES



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Lymphoid Cells and Tissues

Cells:
Lymphocytes (T & B) ; Plasma cells ; Macrophages ; Dendritic cells ; reticular cells

Tissue
Reticular connective tissue ; Diffuse connective tissue ; Lymphoid follicles (nodules)

LYMPH NODES

Generalised structure : (Marieb p 776)


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..................................Location of some of the Lymph Nodes









Other Lymphoid organs and tissue
Draw diagram : Marieb 6th Ed p 777

Spleen ; Thymus; Tonsils ; Peyer’s patches

SPLEEN
Blood cleansing – removes old & worn cells and platelets. Macrophages remove debris

Stores reserves of the broken down rbc’s (Fe from Hb)

Erythrocyte production in fetus

Stores platelets

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The Tonsils

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Pharyngeal tonsils ; Palatine tonsils ; Lingual tonsils





PEYER'S PATCHES

Patches/Nodules of Lymphoid tissue in the mucosa of the digestive tract - including in the appendix









WRITE DOWN THE FUNCTION(S) OF THE LYMPHATIC SYSTEM WITHOUT THE AID OF YOUR TEXT BOOK.

Circulatory Shock
Hypovolemic Shock
Vascular Shock
.............................Describe the above conditions


Ascites is the abnormal collection of fluid in the abdominal cavity, most often as a result of chronic liver disease.

Ascites is a medical condition in which excess fluid begins to puddle within the abdominal cavity. This fluid is outside of the intestines and collects between the abdominal wall and the organs within. In extreme cases, the abdomen expands outward and the intestines actually begin to float within this "lake" of fluid. Ascites is not contagious and poses no risk to others.

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Causes of ascites

Advanced liver failure accounts for the majority of cases, but about 20% of patients with ascites have a cause other than liver disease. These may be secondary to heart failure, kidney disease, or cancer. Rarely, ascites is due to pancreatic disease, a severely underactive thyroid, malnutrition, or tuberculosis.
Still liver disease is the most common cause. There are many types of liver disease, but most are due to excessive alcohol consumption or chronic hepatitis infection. When people have liver disease for a long period of time, healthy liver cells die and gradually replaced by scar tissue. The word "cirrhosis" means "scar tissue" so this condition is often called cirrhosis of the liver. This scar tissue changes the smooth liver surface into lumps and nodules distorting the normal anatomy and disrupting the blood flow out of the liver. The heart continues to pump blood into the liver with each heartbeat. If the blood cannot flow freely outward, there is an imbalance and excessive pressure builds up in the liver tissue. This is called portal hypertension. In simplistic terms, this pressure imbalance causes the surface of the liver to "weep" fluid into the abdominal cavity which accumulates causing ascites.



OEDEMA

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ELEPHANTIASIS

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