L13 Anatomy - Lymphatics

Question 1

Describe Blood vessels

Answer 1

Tubes of various sizes, up to 3cm in diameter. The finest ones are capillaries.
Arteries take blood away from the heart
Veins Bring blood towards the heart
Blood vessel walls have a simple, squamous layer of epithelium - this is referred to as endothelium. Capillaries use the endothelium for exchange between blood and tissues.
The blood vessel walls are made up of smooth muscle, elastic material etc. The smooth muscle only controls the diameter.

Question 2

How does the heart work?

Answer 2

Two pumps in one organ, which are functionally separate but work together. The right pump deals with deoxygenated blood, the left with oxygenated blood.
Each pump has two chambers: an atrium, which receives blood, and a ventricle which pumps blood. The ventricle therefore is thicker, so it can generate greater pressure. Valves ensure one directional flow

Question 3

What is the anatomical position of the heart?

Answer 3

The conical shape of the heart gives it an apex and a base. The apex tilts to the left, while the base is at the posterior side; this leaves the right ventricle facing the front. The heart sits approximately 8-10cm from the centre of the chest

Question 4

What is the flow of blood through the systemic circulation?

Answer 4

Circulation in the entire body, which is started by the left ventricle pumping blood out the aorta. This moves into arteries, then arterioles, then capillaries. There is an enormous network of capillaries throughout the body, which act as exchange vessels.
Blood moves from capillaries into venules then veins, which get progressively larger. As these have no driving force, they use valves to ensure one way flow.
The largest veins empty into the right atrium.

Question 5

Describe Pulmonary Circulation

Answer 5

Pertains to the lungs. Blood runs from the right ventricle through the ‘pulmonary trunk, into two main branches: right pulmonary artery and left pulmonary artery. These lead into smaller branches, and capillaries within the lungs, in which gas exchange occurs.
Oxygenated blood returns to the heart via two pulmonary veins, which empty into the left atrium.
This system is lower pressure than systemic circulation, but handles the same amount of blood.

Question 6

What are Anastomoses, and which areas have lots/none?

Answer 6

This is a generic term which describes the joining together of hollow structures.
In the body, refers to the structure in which branches of arteries have joined together to provide an alternate path for circulation, which acts as ‘collateral’ circulation, in case of a block.

However, they do not guarantee survival of tissue if there is a block. Survival depends on size on anastomoses, whether the block is gradual or not, and how resilient the tissue is.

Areas like the intestines, and around joints have extensive anastomoses
The heart and the brain have little/no anastomoses.

Question 7

Describe vascular disease

Answer 7

A disease of the arterial wall which causes them to narrow as a result of plaque formation (stenosis). If plaques rupture, blood clots can form, which can cut cut off blood supply to an area and cause ischaemia.

Question 8

What is an embolism?

Answer 8

When a clot (thrombi) gets dislodged and travels to distal tissues, causing a blockage in the narrower tissue

Question 9

Do large veins have valves?

Answer 9

No

Question 10

Are anastomoses more common in veins or arteries/arterioles?

Answer 10

Veins

Question 11

How do veins move blood around and back to the heart from the lower limbs?

Answer 11

Veins have to work against gravity, so use the muscles to help them shift the blood.
Blood is sucked into deep veins when calf muscles relax, and pumped upwards towards the heart when they contract

Question 12

What three components make up a neurovascular bundle?

Answer 12

A nerve fibre, a vein and an artery

Question 13

What features of veins predispose towards a venous embolism occurring in the lungs?

Answer 13

Sluggish circulation of veins may mean that thrombi have a greater chance of developing. If one of these breaks off, it is able to travel towards the lungs unhindered because they get larger as they move back towards the heart. The emboli can then get into the right ventricle and be pumped into the lungs, where it will lodge in the smaller arterioles/capillaries, causing a pulmonary embolism

Question 14

What is the break down of plasma vs cells in blood?

Answer 14

55% plasma

45% cells - red and white blood cells

Question 15

How are granulocytes named?

Answer 15

On the staining properties of GRANULES.
Neutrophils: very pale pink
Eosinophils: red/pink
Basophils: purple

Question 16

What two types of WBC’s are agranulocytes?

Answer 16

Lymphocytes and monocytes

Question 17

What does the lymphatic system do?

Answer 17

When small amounts of fluid oozes out of capillaries, not all of it returns to the capillaries. Some tissue fluid moves into lymphatic capillaries, which deals with any micro-organisms in the fluid, in the lymphatic system. This fluid is then returned ‘clean’ to the capillaries.
Acts as a biological filter

Question 18

What are lymph nodes?

Answer 18

Small nodes with an aggregation of defence-related cells, largely lymphocytes although there are other leucocytes and macrophages there too. Lymph nodes are in the paths of lymph vessels, and act as biological filters.
Major lymph nodes are usually where limbs attach to the trunk of the body

Question 19

In which parts of the body do we find the lymphatic system?

Answer 19

In all parts, except the CNS

Question 20

How are lymph nodes set up?

Answer 20

In regional groups, with 2-4 sets before the lymph fluid is returned to the blood

Question 21

What do the Axillary lymph nodes do?

Answer 21

Drain lymph from the entire upper limbs, most of teh thoracic wall including the breasts, and the abdominal wall above the umbilicus

Question 22

What do the Inguinal nodes do?

Answer 22

Drain lymph from the entire lower limb, lower abdominal wall and the perineum

Question 23

Why would lymph nodes get enlarged in certain disorders or diseases?

Answer 23

If you get an infection somewhere in your body, drainage of this infection into the lymphatic system, and therefore the regional lymph node can occur. This can lead to enlarged and painful lymph nodes.
In addition, if cancers get into this area of drainage, cells can break loose of the tumour and get trapped in lymph nodes, and multiply. This is referred to as metastasised cancer.