Blood and Blood Vessels Flashcards
What are arteries?
Blood vessels that carry blood away from the heart
The pulmonary artery…
…carries blood from the right ventricle
The aorta artery…
…carries blood from the left ventricle
Explain the process of diffusion regarding capillaries
capillaries enable diffusion of gasses and solutes - into and out of the blood, occurs in all tissues
Describe capillaries
they’re tiny and the walls are only one cell thick.
substances are able to diffuse through the walls into tissues.
Describe arteries
they are tick walled vessels, their walls have to withstand blood which is sometimes exerting a high pressure
There are 3 layers to the artery, vein and capillary; they are
outer layer - tunica adventitia
middle layer - tunica media
inner layer - tunica intima
What are arterioles?
very small arteries that deliver blood to the capillary beds
What’s the role of arterioles?
Have a key role in regulating blood flow to different organs.
e.g. during emergence such as blood loos, they can constrict which reduces blood flow to some less essential areas such as the skin. More blood is then available for essential organs such as the heart, lungs, brain and skeletal muscle
Describe the pulse and how it can be felt
the pulse can be felt where the artery flows close to the body surface.
it is a wave or pulse of blood due to expansion of the artery during ventricular contraction.
Explain semilunar valves within veins
Veins have semilunar valves which prevent back flow of blood. Valves made from folds of tunica intima (inner layer)
What are ‘venules’?
They’re very small veins; blood flows from arteries into capillaries then into venules then veins which carry blood back to the heart.
Capillaries are ‘exchange vessels’ - what does this mean?
The only blood vessels through which nutrients, gasses, waste from tissues etc can enter or leave the blood
Venous return is aided by 4 factors which are:
- circulating blood volume
- skeletal muscular pump
- respiratory pump
- venoconstriction
Circulating blood volume does what?
Less blood, less pressure in certain area
How does skeletal muscular pumping work?
a. contraction of skeletal muscles
b. leg muscles contracts vein compressed, valve below compressed section of vein closes. Blood in compressed section flows towards heart.
c. when muscle relaxes, blood pressure below the closed valve.
How does respiratory pump work?
During inhalation diaphragm moves down, abdominal veins compressed ^ pressure, combined with negative pressure in thoracic cavity draws blood towards the heart as fluid flows down the pressure gradient towards region of lower pressure
Venoconstriction
Constriction of veins limited as less muscle than arteries but still occurs
Define blood
Blood is a highly specialised, complex, mobile connective tissue in which living blood cells are suspended in a non-living fluid matrix called plasma
Describe blood
- red in colour
- dense and stickier than water
- slightly alkaline pH
- temp 38 degrees C
State the 3 functions of blood
transportation
protection
regulation
Explain the bloods function of ‘transportation’
- oxygen from lungs, CO2 from the cells
- nutrients from the gastrointestinal system to cells
- heat and waste products away from cells
- hormone from the endocrine system to other cells
Explain the bloods function of ‘protection’
- blood clotting in response in injury, prevents blood loss
- contains proteins to protect against disease
Explain the bloods function of ‘regulation’
- pH of body fluids
- involved in temp. regulation - osmotic pressure
The two main components of blood are:
- 55% blood plasma
- 45% formed elements - red blood cells, white blood cells and platelets
What is plasma?
Straw coloured liquid which consists of:
- 91.5% water
- 7% plasma proteins
- albumins help to maintain osmotic pressure
- antibodies
- fibrinogen for formation of blood clots
Name the 5 types of white blood cell
neutrophils lymphocytes monocytes eosinophils basophils
Describe platelets
Cell fragments which are disc shaped and have no nucleus
What does a platelet do?
When blood vessels are damaged the platelets form a platelet plug.
Contain chemicals that promote clotting
3 stages to stop bleeding when blood vessels injured
- vasoplasm
- platelet plug formation
- blood clotting
What is an antibody?
A blood protein produced in response to and counteracting a specific antigen
What is the lymphatic system?
A system of vessels that carry fluid from the tissues, clean it and return it to the blood stream
What do lymph nodes do?
Filter lymphatic fluid, nodes contain many immune cells so immune response is rapid
What does fluid flow through in the lymphatic system?
Lympthnodes
What do capillaries do in the lymphatic system?
Drain excess fluid from the tissues
What determines your blood group?
The presence or absence of various antigens
Why does your blood react with blood that’s not compatible with ours?
Because you’re more likely to have antibodies for antigens your red blood cells lack
Define microbe
a microorganism, especially a bacterium causing disease or fermentation
(a pathogen)
Define macrophages
A macrophage is a type of phagocyte, which is a cell responsible for detecting, engulfing and destroying pathogens and apoptotic cells.
How do macrophages act upon microbes/pathogens?
Once microbes enter the body, macrophages combat them by phagocytosis (ingestion) and remove the remains of dead cells
What’s phagocytosis?
the ingestion of bacteria or other material by phagocytes
Define phagocytes
a type of cell within the body capable of engulfing and absorbing bacteria and other small cells and particles.
What do white blood cells do? (otherwise known as leukocytes)
Combat pathogens and foreign substances that enter the body and most live only a few days or hours during response to infection.
2 types of white blood cells
granulocytes and agranulocytes
contain or do not contain granules
