Blood Flow and Fluid Exchange, Oedema, Lymphatic system, Lymph, and Cancer Spread

Question 1

The negative interstitial fluid pressure is maintained by the…

Answer 1

continuous pumping of proteins into the lymphatic system from the interstitial spaces and the low hydrostatic pressure in lymph vessels.

Question 2

Without this negative pressure there would be…

Answer 2

a net inflow of interstitial fluid into the capillaries.

Question 3

What is diffusion in terms of fluid exchange? Give examples

Answer 3

In the context of biological systems, diffusion is crucial for the exchange of gases (like oxygen and carbon dioxide) and nutrients between blood and tissues. Small molecules like oxygen can diffuse through capillary walls and into body tissues.

Examples: Gas exchange in the lungs (oxygen entering the blood and carbon dioxide exiting), nutrient and waste exchange in capillaries.

Question 4

What is filtration in terms of fluid exchange? Give examples

Answer 4

Filtration is a key process in the kidneys, where blood is filtered to remove waste products and excess substances, forming urine. It also occurs in capillaries, where blood pressure forces fluids and small solutes out of the blood and into surrounding tissues.

Examples: Formation of urine in the kidneys, movement of plasma out of blood vessels and into tissues (as part of the formation of interstitial fluid).

Question 5

The lymphatic system is a group of vessels with three main functions which are…

Answer 5

To collect and return interstitial fluid to the blood vascular system.

To protect against disease.

To absorb lipids from the gastrointestinal tract (GIT).

Question 6

Where there is excess interstitial fluid in the tissues a swelling or ________ of the tissues may occur.

Answer 6

oedema

Question 7

The excess of interstitial fluid is due to…

Answer 7

an increased interstitial fluid pressure from its normal negative value (-6.3 mmHg) to a positive value due to a number of possible disease conditions.

Question 8

Conditions which increase interstitial fluid include…

Answer 8

1. Increased capillary pressure - due to local venous obstruction by blood clots; frequently right cardiac failure, increase in venous pressure.
2. Decreased plasma proteins - severe burns lead to loss of albumin; in nephritis lots of plasma proteins are lost, decrease in P.C.O.P.
3. Lymphatic obstruction - protein accumulation in interstitial fluid, increase I.F.C.O.P. usually due to filariasis.
4. Increased capillary permeability - loss of fluid and protein into the interstitial spaces as a result of burns or allergic reactions.

Question 9

Lymph vessels are like blood capillaries but end __________

Answer 9

blindly in terminal lymphatic capillaries.

Question 10

These have a thin and permeable endothelium with loose ___________ which are free to flap inward forming small non-return valves.

Answer 10

overlapping cells

Question 11

The larger lymphatic vessels with non-return valves function as a ________________ helped by contraction of the body muscles.

Answer 11

lymphatic pump

Question 12

During exercise lymph flow may be ___________________
During rest, lymph flow ___________________

Answer 12

increased five to fifteen times.

is fairly sluggish, about 120ml/hr body.

Question 13

Lymphatic capillaries drain ___________

Answer 13

excess interstitial fluid from the capillary beds.

Question 14

Lymphatic fluid is similar to interstitial fluid and contains…

Answer 14

proteins (2g/100ml), fat droplets, lymphocytes.

Question 15

What are lymph nodes?

Answer 15

Lymph nodes are found at the junctions of lymph vessels.
Masses of two types of white blood cell - lymphocytes and macrophages.

Question 16

The nodes act as the filters of the system stopping…

Answer 16

bacteria and foreign particles.

Question 17

A lymph node from the gut is called a…

Answer 17

Peyer’s patch.

Question 18

What happens to the larger lymphatics in the lower body and the left upper body?

Answer 18

In the abdomen, they drain into a large sac called the cisterna chyli, which lies on the posterior abdominal wall below the liver.

Question 19

From here a single thoracic duct proceeds…

Answer 19

superiorly through the thorax running behind the oesophagus.

Question 20

Fill in the blank:
The right _____________, including right thorax, head and arm, drains through the _________________ and enters the venous system at the junction of the ____________________.

Answer 20

Right upper body, right lymphatic duct, and right subclavian and right jugular veins.

Question 21

True or false: The lymphatic system is equal on both sides.

Answer 21

False, it is NOT equal