Organisation ( part 1) Flashcards
Why are scabs formed ?
To prevent blood loss and to stop microbes from entering the body
How does a scab work ?
- platelets arrive at the site of the wound and group together to act like a plug to stop more blood from getting out
- blood clotting protein fibrogen forms a mesh over the wound
- platelets stick to one another and the mesh, completely covering wound
- clot is formed , becomes a scab as it dries out
What are capillaries ?
Capillaries are small blood vessels which connect arteries to veins. They are the site of exchange between the blood and body tissues.
What are the functions of capillaries ?
- allow oxygen and nutrients for example ( glucose, vitamins, amino acids, fatty acids) to diffuse from blood to cells
- they also allow waste to diffuse from cells to blood
What are the adaptations of capillaries ?
- they have very thin walls of only one cell thick which means a short diffusion pathway
- small lumen which increases surface area to volume ratio
What is the role of a red blood cell ?
Red blood cells transport oxygen around the body
What is the role of a white blood cell ?
Ingesting pathogens and producing antibodies and antitoxins
What is the role of blood plasma ?
plasma carries blood cells suspended in it. It also carries many dissolved substances around the body.
What is the role of platelets ?
platelets are tiny cell fragments involved in blood clotting
Explain some adaptations of a red blood cell
- contain a protein called haemoglobin to carry the oxygen molecules
- no nucleus, which allows for more haemoglobin
- small and flexible so that they can fit through narrow blood vessels
- biconcave shape to increase surface area for oxygen absorption
What substances are carried around the body in blood plasma ?
waste carbon dioxide, urea, and insoluble products of digestion
what is the difference between white blood cells and red blood cells ?
White blood cells are larger than red blood cells and they do have a nucleus
What are the four components of blood ?
platelets, white blood cells, red blood cells and plasma
What do arteries do ?
Carry oxygenated blood away from the heart
* except for pulmonary artery
what do veins do ?
Carry deoxygenated blood towards the heart
* except for pulmonary vein
what is the role of valves ?
Stop the back flow of blood
Blood pressure in capillaries, arteries and veins
fairly low
high
low
Where is the blood pressure highest ?
Near the heart
What is the structure of platelets ?
Irregular shape, no nucleus and are very small
Right hand side of the heart pumps…
deoxygenated blood
left hand side of the heart pumps…
oxygenated blood
What is blood pressure ?
a measure of the force that your heart uses to pump blood around the body
What is the advantage of us having a double circulatory system ?
It ensures that we are providing body tissues with fully oxygenated blood rather than a mixture of oxygenated and deoxygenated blood
What are the two circuits in the double circulatory system ?
Pulmonary circuit and systemic circuit
What happens in the pulmonary circuit ?
- Deoxygenated blood pumps from the heart to the lungs, collecting oxygen
- oxygenated blood goes back to the heart
What happens in the systemic circuit ?
- Heart pumps oxygenated blood to the organs, where the blood transfers oxygen to body cells
- Deoxygenated blood returns to the heart
How does the heart work ?
- blood enters the left and right atrium
- the atria then contract forcing the blood into the ventricles
- the ventricles then contract forcing blood out of the heart
- valves prevent the back flow of blood into the atria when the ventricles contract
What are the adaptations of arteries ?
- thick walls containing a lot of muscle and elastic fibres
the muscle makes the arteries strong and able to withstand high BP and the elastic fibres allow them to stretch when blood passes through - small lumen ( relative to the large vessel) maintains the high blood pressure as blood is transported around the body
What are the adaptations of veins ?
- thin walls because the blood in veins has travelled a long distance from the heart so it is at low pressure
- Large lumen and valves make sure that blood is transported efficiently as blood carried by veins moves slower and often against gravity
What exactly is the heart ?
A muscular organ that pumps blood around the body
What are the two top chambers of the heart called ?
Atria ( left and right atrium)
What are the two bottom chambers of the heart called ?
Ventricles
What does the vena cava do ?
Pumps deoxygenated blood from around the body back to the heart
What is the role of the aorta ?
pumps oxygenated blood away from the heart to the body
What does the left ventricle do ?
pumps oxygenated blood to the body through the aorta
What does the right ventricle do ?
pumps deoxygenated blood to the lungs through the pulmonary artery