Lymphatic System

Question 1

What is the lymphatic system

Answer 1

Thin-walled vessels responsible for the transporting of excess tissue fluid throughout the body which drain into the thoracic duct or right lymphatic duct back into the blood stream
90% returns to circulation via veins

Question 2

Main functions of the lymphatic system

Answer 2

Return proteins, lipids & water from the interstitial fluid to the blood
Immunity against harmful organisms - lymph organs contribute to maturation of immune cells

Question 3

What part of the body does the thoracic duct drain

Answer 3

Almost entire body, pelvic & abdominal cavities and left hand side of the thorax, head & neck & left arm into the subclavian veins at the root of the neck

Question 4

What part of the body does the lymphatic duct drain

Answer 4

Right side of the body, arm upwards into the right subclavian vein at root of the neck

Question 5

What different parts does the lymph system consist of

Answer 5

🍑lymph FLUID
🍑lymph VESSELS
🍑lymph NODES
🍑lymph ORGANS (spleen & thymus)
🍑lymphoid TISSUE (eg tonsils, MALT & GALT)
🍑 bone marrow (lymphocyte production)

Question 6

What is ‘lymph’ & what it contains

Answer 6

A watery fluid similar to blood plasma but with less plasma protein
Same composition of interstitial fluid just called lymph when found in lymph system, contributes to the nourishment of tissues

Contains:
Water
Leukocytes
Leaked out of capillaries, plasma proteins
Fats absorbed from small intestine
Bacteria & cell debris from damaged tissue

Question 7

What are blind-end tubes

Answer 7

A one way structure, like an open drain

Question 8

What is the lacteal

Answer 8

A blind ended lymph vessel in the small intestine

Question 9

Where are lymph capillaries located

Answer 9

In space between cells, veins & arteries

Question 10

What is the structure of lymph vessels

Answer 10

3 layers like veins
Numerous cup shaped valves
Vessels unite to form lymph trunks

Question 11

What is the function of lymph nodes

Answer 11

Filter lymph & remove foreign matter such as microbes, cell debris & tumour cells
Formed of reticular cells & lymphatic tussue
They are filled with immune cells, mainly phagocytes & lymphocytes

Lymph passes through many nodes before returning to the blood, around 600 located in groups along lymph vessels throughout the body

Generally follow same route as veins

Question 12

What vessels do lymph enter via

Answer 12

Afferent, prolific in body

As many as 4-5 afferent lymph vessels can enter a node

Question 13

What vessels do filtered lymph leave via

Answer 13

Efferent, few in body

Only one efferent vessel carries lymph away from the node

Question 14

Where are the 5 main locations of lymph nodes

Answer 14

1. Cervical (neck)
2. Axillary (armpit area)
3. Inguinal (groin)
4. Vertebral column
5. Mesenteric (intestinal) - MALT & GALT dont have afferent lymphatics so not exposed to lymph diseases

Question 15

What can cause lymphadenopathy

Answer 15

During early stages of infection, incomplete phagocytosis of microbes can cause swelling of the lymph nodes, as material filters by passing from node to node

Question 16

What is the white and red pulp of splenic pulp

Answer 16

White pulp contains lymphocytes & macrophages

Red pulp contains all the components of circulating blood

Question 17

What are the main functions of the spleen as a giant lymph node

Answer 17

1. During foetal development - haematopoesis
2. Blood reservoir in adults
3. Phagocytosis of worn out/defective erythrocytes & breakdown products eg bilirubin & iron are transported to liver via portal vein
4. Immunity: T & B lymphocyte maturation

Spleen has no afferent lypmhatics entering so is not exposed to diseases spread by lymph

Question 18

How does the thymus work as another big lymph node

Answer 18

Imprtant role in immune development & antibody production in early life

It contains epithelial cells, T lymphocytes & macrophages
Epithelial cells produce ‘thymosin’ which promotes the maturation of T lymphocytes (produced in red bone marrow)

Atrophy begins in puberty, declining throughout life & replaced with fat

Question 19

What do the lymphatic system rely on for assistance of drainage

Answer 19

🍒mild, rhythmical contractions of the lymph vessels (lymphatic pump) & one-way system
🍒skeletal muscle pump - movement/exercise, especially calves
🍒respiratory pump - during inhalation air pressure drops in the thoracic region, lymph moves from high to low pressure

Question 20

How does the lymphatic system absorb substances

Answer 20

Lacteals (found in the villi of small intestines) absorb fat-soluble substances/nutrients such as dietary fats & fat-soluble vitamins (A, D, E & K)

Question 21

What is the structure of lymph capillaries

Answer 21

Originate as blind-ended tubes in interstitial spaces, same structure as blood capillaries ie single layer of endothelial cells but far more permeable
They join up to form larger lymph vessels

Question 22

What are the three types of tonsil

Answer 22

Palatine - ones visible on wall at back of the mouth

Pharyngeal (adenoids) - lie at back of nasal cavity

Lingual - collections of lymphoid tissue at back & sides of tongue