Gross Anatomy of the Circulation

What are the three types of circulation systems in the human body?

Systemic circulation

pulmonary circulation

specialed circulatory systems

• portal system

• coronary

• foetal

What is the main function of the circulatory system?

To transport oxygen, nutrients, metabolic waste, hormones, etc.

Which side of the heart contains oxygen-rich blood?

The left side.

Which side of the heart contains oxygen-poor blood?

The right side.

What is the portal system?

A specialized circulatory system with a double layer set of capillary beds.

What are the pulmonary arteries and their oxygen status?

Pulmonary arteries are oxygen-poor.

What are the pulmonary veins and their oxygen status?

Pulmonary veins are oxygen-rich.

systemic circulation

• high pressure system

• takes oxygen from left side of heart to body tissues and returns oxygen poor blood to right side of heart

pulmonary circulation

• lower pressure system (than systemic circulation)

• takes blood low in oxygen from right of heart to the lung

• oxygen rich from lungs to left

What is the role of the lymphatic system?

To provide defense and drainage of interstitial fluid.

What does interstitial fluid refer to?

• fluid moves from arteriole end of capillary into interstitial space and fluid moves from interstitial space back into capillary at the venous end

What causes the movement of fluid between capillaries and interstitial spaces?

Hydrostatic pressure moves fluid out, while blood colloid osmotic pressure draws fluid back in.

movement of fluid at arterial end due to pressure

capillary bed pressure is greater than blood colloid osmotic pressure so filtration

movement of fluid at venule end due to pressure

blood colloid osmotic pressure is greater than capillary bed pressure so fluid drawn in → reabsorption

how is remainder of interstitial fluid removed

drained through lymph capillaries

What is oedema?

Swelling caused by fluid not being drained properly.

What is the path of lymph from lymph capillaries to the blood system?

Lymph capillaries → lymph vessels → lymph nodes → lymph trunks → right lymphatic duct or thoracic duct.

What areas does the right lymphatic duct drain lymph from?

From the right side of the head, thorax, and right upper limb.

What role do lymph nodes play in the lymphatic system?

They filter the lymph and function as part of the immune response.

What type of tissue predominates in lymphoid organs?

Connective tissue dominated by lymphocytes.

What are tonsils and their function?

Small masses of lymphoid tissue that play an important role in immunity.

What is the function of the thymus?

It is involved in the development and maturation of T cells.

What does the spleen do?

Removes abnormal blood cells, stores iron, and initiates immune responses.

What is the structure of the thymus?

It has a capsule covering divided into lobules with an outer cortex and a central medulla.

What hormones are released by the thymus?

Thymosin and thymopoietin, which promote T cell development.

What happens when the spleen ruptures?

It can lead to serious internal bleeding.

What are the main roles of the red pulp in the spleen?

Filtering blood of antigens, microorganisms, and worn-out cells.

What is found in the white pulp of the spleen?

Lymphatic tissue and lymphocytes around arteries.

How does lymph flow through a lymph node?

It first enters the subcapsular space, flows through the cortex, paracortex, and medulla.

What type of lymphocytes dominate the cortex of the thymus?

T cells.

What is the primary function of lymphoid cells?

To participate in immune responses as phagocytes and lymphocytes.

What is MALT and its purpose?

Mucosa-associated lymphoid tissue that protects the epithelia of various systems.

What is found in the paracortex of lymph nodes?

Dominated by T cells.

What do the trabecular veins in the spleen do?

They collect filtered blood moving towards the hilum.

What is the significance of the hilum in lymph nodes and the spleen?

It's the area where blood vessels and lymphatics enter and exit.

Which system of the circulatory system operates at lower pressure?

Pulmonary circulation.