Course Content
KCP 1 – Obesity (Lectures)
This covers all the lecture content from the key clinical problem "Obesity" for cellular response 3.
Cellular Response 3
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Overview of circulation

Learning outcome 1.Describe the types of blood circulation.

There are two main types of blood circulation in the body: pulmonary circulation and systemic circulation.



Pulmonary circulation is the flow of blood from the heart to the lungs, where it picks up oxygen and releases carbon dioxide. The oxygen-rich blood then returns to the heart and is pumped to the rest of the body.



Systemic circulation is the flow of blood from the heart to the rest of the body, delivering oxygen and nutrients to the tissues and removing waste products. The blood then returns to the heart to repeat the cycle.



Both of these circulations work together to provide the body with the oxygen and nutrients it needs to function properly and maintain homeostasis.



Learning outcome 2.Describe the lymphatic system and circulation.

The lymphatic system is a part of the immune system that helps maintain fluid balance in the body. It consists of a network of vessels, tissues, and organs that work together to filter and transport excess fluid, waste products, and foreign substances away from the tissues. The fluid is called lymph and is similar in composition to blood plasma.



The lymphatic circulation begins in the tissues and travels through lymphatic vessels to larger vessels and eventually to the bloodstream. Along the way, the lymph is filtered by lymph nodes and other tissues, where immune cells, such as lymphocytes, can remove harmful substances and initiate an immune response.



The lymphatic system also has a role in absorbing fat from the intestines and transporting it to the bloodstream for energy use. Additionally, the lymphatic system helps regulate fluid balance by returning excess fluid to the bloodstream.



The lymphatic system plays an important role in the body’s defense against infections and other harmful substances. It also helps maintain fluid balance and plays a role in fat metabolism.


Learning outcome 3.Describe the function of the circulatory system.
  • The circulatory system, also known as the cardiovascular system, is a complex network of blood vessels and organs that transport blood, oxygen, and other nutrients to the body’s tissues and organs. The main function of the circulatory system is to maintain the balance of oxygen and other essential nutrients in the body, and to transport waste products away from the tissues and organs.



  • The circulatory system is composed of the heart, blood vessels, and blood. The heart acts as a pump, contracting and relaxing to circulate blood throughout the body. Blood vessels, including arteries, veins, and capillaries, carry blood to and from the tissues and organs. Blood is composed of red blood cells, white blood cells, and plasma. Red blood cells carry oxygen to the tissues, while white blood cells help to defend the body against infection. Plasma carries nutrients, waste products, and hormones throughout the body.



Overall, the circulatory system plays a vital role in the body’s health and function, providing essential oxygen and nutrients to the tissues and organs, removing waste products, and helping to maintain homeostasis.

Learning outcome 4.Describe the fluid compartments of the body.

The body’s water content is divided into two main compartments: Extracellular Fluid (ECF) and Intracellular Fluid (ICF).



  • Extracellular Fluid: This is the fluid outside of cells and makes up approximately 1/3 of the body’s total fluid volume (33% of total body water). It contains ions and nutrients needed for cellular life.
  • Intracellular Fluid: This is the fluid inside the cells and makes up approximately 2/3 of the body’s total fluid volume (67% of total body water).

Learning outcome 5.Compare and contrast whole blood, plasma and serum.

Whole blood refers to the blood in its entirety and contains red blood cells, white blood cells, platelets, and plasma. Plasma is the liquid component of blood that makes up about 55% of whole blood and is responsible for transporting various substances throughout the body. It contains water, electrolytes, proteins, hormones, and waste products.



Serum is plasma that has had the clotting factors removed and is often used in laboratory testing to assess various components of the blood such as electrolytes, glucose, and liver function. In contrast, plasma contains clotting factors necessary for blood clotting and wound healing.



In summary, while whole blood is the total blood in the body, plasma is the liquid portion of whole blood, and serum is a type of plasma without the clotting factors.

Learning outcome 6.Describe the processes that allow the exchange of fluids and nutrients across capillary walls.
  • The capillary endothelium allows the exchange of fluids and nutrients by several mechanisms: diffusion, vesicular transport, active transport, and bulk flow.



  • Starling’s forces determine the rate of fluid movement in and out of the capillaries.



Starling’s forces:



  • Hydrostatic pressure: pushes fluid out of the capillaries
  • Osmotic pressure: draws fluid into the capillaries
  • Interstitial fluid colloid osmotic pressure
  • Oncotic pressure




These forces determine the exchange of fluid across the capillary walls and result in filtration or reabsorption of fluid. The balance of these forces regulates blood pressure, fluid balance and overall homeostasis in the body.

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