Blood and blood vessels Flashcards
(14 cards)
What are the five types of blood vessels?
Arteries, Arterioles, Capillaries, Venules, Veins
These vessels have distinct functions and structures in the circulatory system.
What is the tunica media?
A layer made up of smooth muscle cells, elastic tissue, and collagen, located between the tunica intima and tunica externa.
The tunica media is responsible for the contraction and relaxation of blood vessels.
Define lumen in biological terms.
The inside space of a tubular structure, such as an artery or intestine, through which blood flows.
The term comes from Latin ‘lumen’, meaning ‘an opening’.
What are the characteristics of arteries?
Large vessels with small lumen, thick muscular walls, and able to withstand greater pressure.
They contain large amounts of elastin, allowing them to stretch and recoil.
What is the role of arterioles?
Connect arteries to capillaries and control the flow of blood into the capillaries.
They have muscular walls that can adjust diameter.
What is the pre-capillary sphincter (PCS)?
A ring of muscle surrounding the arteriole that can contract to divert blood away from the capillary.
It plays a crucial role in regulating blood flow.
Describe capillaries.
Vessels that are one cell thick, enabling nutrient and gas exchange, with much lower pressure for diffusion.
They consist only of tunica intima and have no muscular walls.
What do venules do?
Connect capillaries to veins and collect blood before it empties into the veins.
They have much less pressure than arteries.
What are veins characterized by?
Large lumen, thinner walls than arteries, and valves to prevent backflow of blood.
The flow of blood back to the heart is known as venous return.
What are the components of blood?
Red Blood Cells (RBC), White Blood Cells (WBC), Platelets, Plasma
Each component has a specific function in the circulatory system.
What is the primary function of Red Blood Cells (RBC)?
To carry oxygen around the body via haemoglobin (Hb).
Oxygen attaches to haemoglobin to form oxyhaemoglobin.
What is the role of White Blood Cells (WBC)?
To protect the body from infection and disease by attacking foreign bodies.
They remain inactive in the blood until needed.
What do platelets do?
Help clot blood to minimize bleeding and form scabs when needed.
They are usually inactive but swarm to areas of injury.
What is plasma?
The fluid that enables all other blood cells to move around the body, making up approximately 50% of blood volume.
It allows for quick and effective transportation of cells.
