Topic 4.3 Circulation Flashcards
State the features of a mass transport system
- system of vessels which carry substances
- a way of making sure substances are moved in the right direction
- a means of moving materials fast enough to supply the needs of the organism e.g. through a pump mechanism or concentration gradient
- a suitable transport medium
Define a single circulatory system
a circulation in which the heart pumps the blood to the organs of gas exchange and then the blood travels on around the body before returning to the heart
Define a double circulation system
a circulation that involves 2 circulatory systems, one of deoxygenated blood flowing from the heart to the gas exchange organs and back oxygenated to the heart, the other oxygenated blood flowing from the hearts to the muscles, returning deoxygenated blood to the heart
Describe the circulatory system in a fish
single circulation system. heart pumps deoxygenated blood to the gills where the blood takes in oxygen and becomes oxygenated, giving up CO2 at the same time. blood then travels around the fish, giving up oxygen to the body cells before returning to the heart
Why do birds mammals need more oxygen than fish?
- not constantly in water
- maintain a higher body temperature that is higher than their surroundings
- need lots of oxygen and glucose and to remove lots of waste products quickly
What are the 2 systems in a double circulatory system?
systematic and pulmonary
What is the function of the systematic system in the double circulation system?
carries oxygenated blood from the heart to the cells where it is used and then carries deoxygenated blood back to the heart
What is the function of the pulmonary system in the double circulation system?
carries deoxygenated blood from the heart to the lungs where it becomes oxygenated, and carries the oxygenated blood back to the heart
State the advantages of a double circulation system
-oxygenated and deoxygenated blood don’t mix, so tissues receive as much oxygen as possible
-fully oxygenated blood delivered quickly to the working muscles at high pressure
-blood going through the tiny blood vessels is at low pressure so they don’t get damaged + allows gas exchange to take place
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What is the cardiovascular system?
the mass transport system of the body made up of the blood vessels and the heart- the pump to move blood through the vessels
What is the transport medium in the cardiovascular system?
the blood
Define circulation
the passage of blood through the blood vessels
Apart from circulation, what are the other functions of the cardiovascular system?
- carrying hormones
- forming part of the defence system of the body
- distributing heat
What 4 things are contained in the blood?
- plasma
- platelets
- erythrocytes
- leucocytes
What is the role of the plasma?
transport of…
- digested food products e.g. glucose and amino acids from the small intestine to body parts that need them or for storage
- nutrient molecules from storage areas to cells that need them
- excretory products e.g. carbon dioxide and urea from cells to the organs e.g. lungs or kidneys that secrete them
- hormones from where they are made to where they cause change
Apart from transport, what else does the plasma do?
maintains a steady body temp by transferring heat around the system from deep-seated organs to active tissues
acts as a buffer to pH change
What to erythrocytes contain?
haemoglobin
What is haemoglobin?
a red pigment which carried oxygen
Describe the structure of an erythrocyte
- mature erythrocytes do not contain a nucleus=more space for haemoglobin
- biconcave disc shape=large SA:V
State the function of erythrocytes
transport oxygen around the body
Give some characteristics of leucocytes
- larger than erythrocytes but can squeeze through tiny blood vessels by changing shape
- formed in bone marrow and some mature in the thymus gland
- contain a nucleus
- colourless cytoplasm
- some contain granules
What is the function of leucocytes?
to defend the body against infection
Name the 2 different types of leucocytes
granulocytes and agranulocytes
What are the different types of granulocytes?
- neutrophils
- eosinophils
- basophils
What are the different types of agranulocytes?
- monocytes
- lymphocytes
Define granulocytes
leucocytes which contain granules in the cytoplasm that can take up stain are are obvious under a microscope. they have lobed nuclei
Define agranulocytes
leucocytes which do not have granules in their cytoplasm and they have unlobed nuclei
State the function of neutrophils
a granulocyte which is part of the non-specific immune response, they engulf and digest pathogens by phagocytosis. they have multi-lobed nuclei (up to 70% of leucocytes are neutrophils)
State the function of eosinophils
a granulocyte which is part of the non-specific immune system, they are stained red by eosin stain. important against parasites, in allergic reactions and inflammation as well as developing immunity to disease
State the function of basophils
granulocytes part of the non-specific immune system and have 2 lobed nucleus. they produce histamines involved in inflammation and allergic reactions
State the function of monocytes
agranulocytes that are part of the specific immune response and are the largest of the leucocytes. they can move out of the blood to the tissues to form macrophages, they engulf pathogens by phagocytosis
State the function of lymphocytes
agranulocytes which a small with large nuclei and important in the specific-immune response
What are agranulocytes important in?
the specific-immune system
What are granulocytes important in?
non-specific immune system
What are platelets?
they are tiny fragments made from large cells called megakaryocytes, found in the bone marrow
What are the role of platelets?
involved in blood clotting- the clotting cascade
During an injury, what flows from the cut blood vessel?
plasma, blood cells and platelets
What causes the platelets to break open?
contact between the platelets and tissue components e.g. collagen fibres
Which 2 important substances do platelets release?
- serotonin
- thromboplastin
What’s the role of serotonin?
causes the smooth blood vessel to contract so that it narrows and restricts blood flow to the damaged area
What is the purpose of thromboplastin?
it is an enzyme used in the clotting cascade which starts it off
Which vitamin is important in the clotting cascade?
vitamin K
Why is vitamin K important in the clotting cascade?
producing many of the components in the cascade such as prothrombin
What is the first stage of the clotting cascade?
- thromboplastin catalyses the conversion of a large soluble plasma protein, prothrombin into a soluble protein and enzyme, thrombin. this happens at the site of the wound
What conditions must be present for the first stage of the clotting cascade to happen?
calcium ions at the right concentration
Describe the second stage of the clotting cascade
- thrombin acts on another soluble protein, fibrinogen, converting it to an insoluble substance, fibrin which forms a mesh over the wound
What is the third stage of the clotting cascade? (after a mesh has been formed)
more platelets and blood cells from the wound get trapped in the fibrin mesh, forming a clot
Describe the final stage of the blood clotting cascade
special proteins in the platelet structure contract, making the clot tighter and tougher to form a scab which protects the skin and vessels underneath as they heal
Why can blood clotting be detrimental to health?
if the cascade is triggered at the wrong place, for example near the heart which restricts the blood flow, causing a heart attack or the brain, causing a stroke
State the characteristics of haemoglobin
- large globular protein
- 4 polypeptide chains
- quaternary structure
- iron containing group in each chain
What is the bonding of haemoglobin with oxygen like?
- can pick up 4 oxygen molecules in a reversible reaction to form oxyhaemoglobin
- 1st oxygen to bind alters the arrangement of the molecule so it is easiest for the next oxygens to bind
- final oxygen binds much quicker then the first
- in dissociation, it gets progressively harder to remove oxygen
Describe the affinity for oxygen in haemoglobin
haemoglobin has a high affinity for oxygen so a small change in the partial pressure of oxygen in the surrounding has a big effect on blood saturation wit oxygen
Describe the oxygen dissociation curve for haemoglobin
- sigmoid curve
- at the top of the curve there is a high partial pressure of O2 (conditions in the lungs
- at the bottom of the curve there is a low partial pressure of oxygen (conditions in respiring tissues)
Describe the Bohr effect
- shifts the oxygen dissociation curve to the right
- haemoglobin saturation is affected by CO2 proportion in the tissues
- when pp of CO2 is high, affinity for oxygen is reduced so oxygen is given up easier
What is fetal haemoglobin?
- found in developing fetus- dependent on mother for oxygen
- oxygenated blood from the mother runs through the placenta close to the deoxygenated fetal blood
- fetal haemoglobin has a higher affinity for O2 than mother so removes O2 from maternal blood
- counter current exchange system
Describe myoglobin
- respiratory pigment found in muscles
- similar structure to a single haemoglobin strand
- contains a haem group which O2 binds to
- myoglobin has a higher affinity for O2 than haemoglobin which isn’t affected by ppO2
- good O2 stores as doesn’t give it up easily
Define atherosclerosis
a condition where yellow fatty deposits build up on the lining of arteries, causing them to narrow and result in many health problems
What is an atheroma?
a plaque formed on the arterial lining, yellowish fatty deposits
Name the reasons for the damage to the endothelium lining
- high blood pressure
- chemicals in tobacco smoke
Describe the process of atherosclerosis
1) damage occurs to the endothelium lining
2) the body’s inflammatory response begins and WBCs arrive at the site of damage
3) WBCs accumulate chemicals from the blood (particularly cholesterol)
4) fibrous tissue and calcium salts also build up around the atheroma, turning it into a hardened plaque, meaning the artery wall hardens making it less elastic
5) lumen is smaller which increases blood pressure and makes it harder for the heart to pump blood around the body so likelihood of plaques forming increases
What is tissues fluid?
the fluid that surrounds all the cells in the body
What are the 2 factors involved in the formation of tissue fluid?
1) water potential
2) hydrostatic pressure
Describe the 2 factors involved in forming tissue fluid
- water potential= plasma exerting an osmotic effect which gives the blood a low water potential of-3.3.kPa. tissue fluid is roughly -1.3kPa so water moves out of the blood by osmosis. pressure behind this movement is oncotic pressure= -2kPa.
- hydrostatic pressure= the residual pressure from the heartbeat that is still present as the blood enters the arterial end of the capillary beds. this tends to force fluid out of the leaky capillary walls
What is the equation to determine oncotic pressure?
oncotic pressure= water potential inside the capillary- water potential outside the capillary
Define oncotic pressure
the tendency for water to move in or out of the capillary by osmosis
What determines whether tissue fluid moves into or out of the capillaries?
the balance between oncotic pressure and hydrostatic pressure
What are spiracles in insects?
found along the thorax and abdomen of most insects. it is the site of entry and exit of respiratory gases. can be opened or shut by sphincters. controls water loss
What are the tracheae in an insect?
the largest tubes of the respiratory system. carry air directly to the body for gas exchange. supported by chitin spirals, hold trachea open when insect moves and compresses its body. chitin is impermeable to gases so little gas exchange occurs. they branch into tracheoles
What are tracheoles?
minute tubes with no chitin lining. they are freely permeable to gases, where most gas exchange takes place
How does the gas exchange system in insects work?
- air enters the spiracles although these are mainly kept shut by sphincters to minimise water loss
- air moves along the trachea and tracheoles by diffusion alone, large network of tracheoles gives a large SA.
- tracheoles may contain water which limits gas penetration for diffusion. however, when insect is very active, lactic acid builds up and dissolves in the water which changes osmotic concentration so water moves out of cells
4) once water moves out the cells, there is additional space for diffusion
Which components of the blood are active enzymes in the blood clotting process?
thrombin and thromboplastin
State the role of platelets in the blood clotting process
forms a plug/mesh to seal the blood vessel/wound
releases clotting factors/thromboplastin
