B3.2 Transport Flashcards
What are 2 examples of organs where there are dense capillary networks?
The Lungs and small intestine.
What is the average width of a capillary?
10 micrometres
Why do capillaries have a large total surface area?
They branch and rejoin repeatedly to form a network with a huge total length.
How to blood cells pass through capillaries?
Blood cells pass through in a single file?
What supports the one layer of endothelium cells in blood capillaries?
A coating of extracellular fibrous proteins.
What is a protective role of the basement membrane?
It filters macromolecules such as proteins, allowing only small or medium-sized particles to pass through.
What features allows fluid to pass through the blood capillaries?
- The blood pressure inside is higher than the surrounding tissues.
- Pores between the epithelium allow the fluid to pass through.
How do the capillaries supply oxygen and other useful substances to the cells in the surrounding tissues?
By releasing tissue fluid containing oxegyn, glucose, and other useful substances to flow between cells and allow them to absorb useful substances and excrete waste products.
What is the function of Arteries?
They carry pulses of high-pressure oxegyn aged blood from the heart to every organ of the body.
What is the function of veins?
They carry a stream of low pressure deoxygenated blood from the organs back to the heart.
What are the structural adaptations of arteries?
- Thicker walls
- Narrow Lumen
- Corrugated inner surface
- Fibers in the walls
What are the visible structural adaptations of veins?
- Thinner walls
- Wider Lumen
- Circular/Flattened
- Smooth inner surface
- No/few fibers visible in walls
What are the general layers of arteries and veins?
- Tunica Externa
- Tunica Media
- Tunica Intima
- Lumen
What are the adaptations (form and func) of the artery tunica externa?
- Its connective tissues contain tough collagen fibers that prevent swelling, bursting, or aneurysms during high blood pressures.
What are the adaptations (form and func) of the artery tunica externa?
- Its connective tissues contain tough collagen fibers that prevent swelling, bursting, or aneurysms during high blood pressures.
What are some adaptations of the artery tunica media?
- Thick layer for strength
-Contains smooth muscle and elastic fibers to help pump blood by transmitting the pulse.
What are some adaptations of the artery tunica intima?
- It’s lined by smooth endothelium that reduces resistance to flow.
- In some arteries there is a layer of elastic fibers.
What are some adaptations of the arterial lumen?
- It’s a narrow space so it helps maintain high blood pressure and velocity of blood flow.
Collagen Fibres
Rope-like proteins with high tensile strengths
State the structural changes that occur within arteries with systole and diastole:
- (systole - ventricles pump, high pressure blood enters) Wall of artery expands due to the high pressure and elastic fibers in the wall stretch and store potential energy.
- (Diastole -ventricles stop pumping, blood pressure declines) elastic fibers recoil, applying pressure on the lumen which helps pump blood on along the artery and makes flow more even.
How are smooth walls in artery walls adapted to their function?
- They are circular, so they make the lumen narrower during vasoconstriction and wider during vasodilation.
- There is a high density of smooth muscle fibers in arterioles, so flow rate of blood in each organ can be adjusted depending on need.
Systole
When ventricles pump blood, a time of high pressure.
Diastole
When ventricles stop pumping blood, a time of lower blood pressure.
How can you measure pulse rate?
- Place your index and middle finger on your carotid or radial artery until the pulse is reliably felt.
- User a timer to count beats per minute.
How does a pulse oximeter work?
It has LEDS that shine light into the finger and detectors to measure how much light is absorbed by the finger, which depends on the amount of blood in the tissues.
What are some adaptations in the layers of veins?
- Tough outer coat of connective tissue in the externa to prevent leak.
- Few elastic fibres in the thin media as blood pressure is low.
- Smooth endothelium in intima to resistance to flow.
- Wide lumen to accommodate slow-flowing blood.
Describe the structure of valves in the veins:
- Tissue consisting of three pocket-flaps of tissue.
Why does deoxygenated have a risk of back flow towards the arteries?
- Very low blood pressure and no pulse.
How do valves prevent the risk of backflow to the capillaries in veins?
- If blood starts to flow backwards, it gets caught in the flaps, filling them and closing the valve. Blood flowing towards the heart will push the valve open.
How many coronary arteries are there?
3
Outline the function of the coronary arteries branching from the aorta:
Supply blood to the muscular wall of the heart.
Atheroma
Deposits of lipids (fats or cholesterol) in the walls of arteries.