human transport Flashcards
what is the blood composed of
45% red blood cells
white blood cells <1%
platelets <1%
55% plasma
what is the role of plasma in transport?
transports:
- CO2
- digested food & mineral ions
- urea
- hormones
- heat energy
how does plasma transport CO2?
dissolved in plasma as hydrogen-carbonate ions and transported from respiring cells to the lungs
how does plasma transport digested food and mineral ions?
dissolved particles absorbed from the small intestine and delivered to requiring cells around the body
how does plasma transport urea?
dissolved in the plasma and transported to the kidneys
how are red blood cells adapted?
- full of haemoglobin, a protein that binds to oxygen to form oxyhaemoglobin
- no nucleus - allows more space for haemoglobin to be packed in
- biconcave disc - large surface area to volume ratio to maximise diffusion of oxygen
what is the role of phagocytes?
carry out phagocytosis by engulfing and digesting pathogens
how do phagocytes carry out phagocytosis?
- have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells
- Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it
- This is a non-specific immune response
what is the role of lymphocytes?
To produce antibodies
What are antibodies?
Y-shaped proteins with a shape that is specific to the antigens on the surface of the pathogen
How do antibodies destroy pathogens?
- Antibodies attach to the antigens and cause agglutination (clumping together)
- So, the pathogenic cells cannot move very easily
- At the same time, chemicals are released that signal to phagocytes that there are cells present that need to be destroyed
what is an antigen?
a molecule found on the surface of a cell
what is the point of vaccinations?
to induce immunity to infectious diseases
How do vaccines work?
- Lymphocytes recognise the antigens in the bloodstream
- The activated lymphocytes produce antibodies specific to the antigen encountered
- Memory cells and antibodies subsequently remain circulating in the blood stream
- Future infection by the same pathogen will trigger a response that is much faster and much larger compared to the initial response
- Due to the rapid nature of the response, the pathogen is unable to cause disease and the individual is said to be immune
why are vaccines important?
reduce the likelihood that an infected individual will spread the pathogen to others
what is the role of platelets?
fragments of cells that are involved in blood clotting
how do platelets cause blood clotting?
- When the skin is broken platelets arrive to stop the bleeding
- A series of reactions occur within the blood plasma
- Platelets release chemicals that cause SOLUBLE FIBRINOGEN PROTEINS to convert into INSOLUBLE FIBRIN and form an insoluble mesh across the wound, trapping red blood cells and therefore forming a clot
- The clot eventually dries and develops into a scab to protect the wound from bacteria entering
WHAT’S THE IMPORTANCE of blood clotting
prevents continued / significant blood loss
prevents entry of microorganisms that could cause infection
where does oxygenated blood come from
from the lungs enters the left side of the heart and is pumped to the rest of the body (the systemic circuit)
where does deoxygenated blood come from
from the body enters the right side of the heart and is pumped to the lungs (the pulmonary circuit)
why does the left ventricle have a thicker muscle wall than the right
it has to pump blood at high pressure around the entire body,
do veins pump blood towards or away from the heart?
Blood is pumped towards the heart in veins
do arteries pump blood towards or away from the heart?
away from the heart
what is. the role of valves?
to prevent backflow of blood
describe the pathway of blood through the heart
- DEOXYGENATED BLOOD coming from the body flows through the vena cava and into the right atrium
- The atrium contracts and the blood is forced through the TRICUSPID VALVE into the right ventricle
- The ventricle contracts and the blood is pushed through the SEMILUNAR VALVE into the pulmonary artery
- The blood travels to the lungs and moves through the capillaries past the alveoli where GAS EXCHANGE takes place
- LOW PRESSURE blood flow on this side of the heart prevents damage to the capillaries in the lungs
- Oxygenated blood returns via the PULMONARY VEIN to the left atrium
- The atrium contracts and forces the blood through the BISCUSPID VALVE into the left ventricle
- The ventricle contracts and the blood is forced through the SEMILUNAR VALVE and out through the aorta
how does exercise affect heart rate?
cells of the muscles respire more rapidly in order to provide energy for muscle contraction
increase in respiration means an increase in requirement for oxygen and glucose as well as an increase in production of waste products that need to be removed
- HEART RATE INCREASES to deliver oxygen and glucose and remove waste more frequently
- VOLUME OF BLOOD pumped out of the heart also increases to deliver bigger quantities of oxygen and glucose
what else increases heart rate?
adrenaline increases heart rate as part of a ‘fight or flight’ response
At the end of a period of exercise why might the heart rate keep high?
oxygen is required in the muscles to break down the lactic acid from anaerobic respiration
This is how the oxygen debt is paid off
what are causes or coronary heart disease?
- Obesity
- Carrying extra weight puts a strain on the heart
- Increased weight can lead to diabetes which further damages your blood vessels - High blood pressure
- This increases the force of the blood against the artery walls and consequently leads to damage of the vessels - High cholesterol
- Speeds up the build up of fatty plaques in the arteries leading to blockages - Smoking
- Chemicals in smoke cause an increase in plaque build up and an increase in blood pressure
- Carbon monoxide also reduces the oxygen carrying capacity of the red blood cells
