3.1.2: transport in animals Flashcards
why are specialised transport systems needed?
- metabolic demands demands of most multicellular animals are high so diffusion over long distances isn’t enough
- sa:v is small
- molecules may be needed in one place but needed in another
- food will be digested but needs too be transported to every cell for respiration
- waste products need to be removed from cells and transported to excretory organs
what is an open circulatory system?
the transport medium isn’t carried in vessels and is pumped straight from the heart into the body cavity of the animal
what is an example of an animal with an open circulatory system?
in insects
how does an insects circulatory system work?
they don’t have blood but they have a fluid called haemolymph. it is pumped out of the heart and and passes into the body cavity, haemocoel. molecules are transferred between haemolymph and body cells then the haemolymph goes back to the heart
what is a closed circulatory system?
the blood is enclosed in blood vessels and doesn’t come directly into contact with the body cells. substances leave and enter the blood by diffusion through the walls of the blood vessels
is an open circulatory system rapid or slow?
slow
is a closed circulatory system rapid or slow?
rapid
true or false: the amount of blood flowing in an open circulatory system can be adjusted
false
true or false: the amount of blood flowing in an closed circulatory system can be adjusted
true
what is an example of an animal that has a closed circulatory system?
in mammals and in fish
what are 3 different components of blood vessels?
elastic fibres, smooth muscle and collagen
what is the function of elastic fibres in blood vessels?
provide flexibility because they can stretch and recoil
what is the function of smooth muscle in blood vessels?
contracts and relaxes, changing the size of the lumen
what is the function of collagen in blood vessels?
provides structural support to maintain the shape and volume of the vessel
what do arteries do?
carry mainly oxygenated blood away from the heart to the tissues of the body
what are the 2 arteries that carry deoxygenated blood?
pulmonary artery and the umbilical artery
what do the elastic fibres in arteries do?
enable them to withstand the force of blood and take the blood at greater volumes. these also recoil which helps to even out surges of blood pumped
what does the smooth muscle in arteries do?
allows the blood to flow easily
what does the collagen in arteries do?
maintains the stretch when blood is pumped at a high pressure
what are arterioles?
they link arteries and capillaries together
what are capillaries?
microscopic blood vessels that link the arterioles to the venules, forming an extensive network through the tissues and used for gas exchange
what are the adaptations of the capillaries?
- large surface area for diffusion in and out of blood
- total cross-sectional area is greater than the arteriole, slowing down blood flow, giving more times to exchange substances
- one cell thick wall so their is less distance for diffusion
what do veins do?
they carry deoxygenated blood, apart from 2 veins, towards the heart from the cells to the heart
what are the 2 veins that carry oxygenated blood?
pulmonary vein and umbilical vein
where does the inferior vena cava transport blood from?
the lower parts of the body
what does the superior vena cava transport blood from?
the head and upper body
why don’t veins have pulse surges?
they are lost when travelling in the capillaries because the blood pressure is low
why do veins have valves?
blood is travelling at a low blood so it is to prevent back flow of blood
what do venules do?
link capillaries with veins together
what are the adaptations of the veins?
- one way valves to prevent back flow
- using the breathing movement as a pump. the pressure changes and the squeezing action moves blood towards the heart
what blood vessel journey does oxygenated blood take?
arteries > arterioles > capillaries > venules > veins
what are the components of blood?
plasma, platelets, red blood cells and white blood cells
what are the 4 chambers of the heart?
the right atrium, right ventricle, left atrium and left ventricle
what is the name of the section of the heart that separates the left and right side?
the septum
what is the name of the valves that separate the atrium and ventricle?
atrio-ventricular valves
what is the name of the valves that separate the ventricle and the arteries?
semi-lunar valves
why is the human circulatory system a double pump system?
the heart pumps blood to the lungs (deoxygenated blood) and to the rest of the body (oxygenated blood)
what journey does blood take starting with the vena cava?
rest of the body > vena cava > right atrium > atrio-ventricular valves > right ventricle > semi-lunar valves > pulmonary artery > lungs > pulmonary vein > left atrium > atrio-ventricular valves > left ventricle > semi-lunar valves > aorta > rest of the body
what is the stroke volume?
the volume of blood pumped each time the ventricles contract
what is cardiac output?
total volume of blood that the heart can pump each minute
what is the equation for cardiac output?
cardiac output (cm^3) = stroke volume (cm^3) x heart rate (per minute)
what does the plasma in the blood do?
is the liquid that carries all the components of the blood: platelets, red blood cells, white blood cells, hormones and large plasma proteins
why is large plasma protein, albumin, important?
maintains the osmotic potential of the blood
why is large plasma protein, fibrogen, important?
involved blood clotting
why is large plasma protein, globulin, important?
involved in transport and the immune system
where are platelets found?
red bone marrow
what do platelets do?
involved in the blood clotting mechanism
what does blood transport?
- oxygen to and carbon dioxide from respiring cells
- digested food from small intestines
- nitrogenous waste products to excretory organs
- hormones
- food molecules from storage compounds to cells
- platelets to damaged areas
- cells and antibodies in immune response
what makes up tissue fluid?
everything present in blood plasma like oxygen, water, nutrients and amino acids, but not red blood cells or big plasma proteins
why does tissue fluid not have red blood cells or large plasma proteins?
they’re too big to push out of the capillary wall through fenestrations
how does the tissue fluid interact with cells?
take in oxygen and nutrients and release metabolic waste into the tissue fluid
explain how the blood enters and leaves the tissue?
- at the start of the capillary bed, near the arteries, the hydrostatic (liquid) pressure inside the capillaries is higher than the in the tissue fluid
- difference in hydrostatic pressure forces fluid out of the capillaries and into spaces around the cells, forming tissue fluid, as well as hydrostatic pressure being higher than oncotic pressure
- as fluid leaves, hydrostatic pressure reduces in the capillaries, so the hydrostatic pressure is much lower at the end of the nearest to the venules
- oncotic pressure is also at work
- oncotic pressure is generated by plasma proteins, mainly albumin, present in the capillaries, which lower the water potential
- at the venule end, the water potential in the capillaries is lower than the water potential in the tissue fluid due to the water loss from the capillaries and high oncotic pressure
- this means water reenters the capillaries by osmosis
where does the fluid that doesn’t reenter the capillaries go?
does eventually get returned to the blood through lymphatic system
what is the lymphatic system?
a drainage system made out of lymph vessels
what composes lymph?
similar composition to plasma and tissue fluid but has less oxygen and fewer nutrients and contains fatty acids
what is the job of the lymph nodes?
where lymphocytes build up when necessary and produce antibiotics, which are than passed into the blood. they also intercept bacteria and other debris, which are ingested by phagocytes
what are enlarged lymph nodes a sign of?
that the body is fighting off an invading pathogen
