organising animals and plants Flashcards
what is the thorax?
the top part of your body. (that is it)
what is the path of air to get to the alveoli?
oesophagus → trachea → bronchi → bronchioles → alveoli.
how does gas exchange work at the alveoli?
the lungs contain millions of alveoli air sacs, surrounded by blood capillaries.
1. blood passing next to the alveoli has just returned from the body and has a lot of carbon dioxide. (little oxygen)
2. oxygen diffuses out the alveoli to the blood and carbon dioxide does the opposite.
what is the double circulatory system comprised of?
humans have 2 circulation circuits joined together.
1. right ventricle (deoxygenated blood) → lungs (now oxygenated) → heart.
2. left ventricle (oxygenated blood) → other organs (becomes deoxygenated) → heart.
how does the heart pump blood around the body?
- into the 2 atria.
(vena cava → right atrium (no oxygen))
(pulmonary vein → left atrium (oxygen)) - atria contracts pushing blood.
(right atrium → pulmonary artery (no oxygen))
(left atrium → aorta (oxygen)) - blood flows to the organs through arteries and back to the heart through veins.
what is a pacemaker?
a group of cells in the right atrium wall that produce electric impulses contracting heart muscles.
what are the 3 blood vessels?
- arteries - carry blood away from heart.
- capillaries - exchange of minerals at tissues.
- veins - carry blood to the heart.
what are the properties of arteries?
walls are strong and elastic.
walls are thick compared to the lumen. (hole)
thick layers of muscle.
what are the properties of capillaries?
very small lumen. (hole)
1 cell thick wall.
supply food and oxygen and take away CO₂.
arteries branch into capillaries.
what are the properties of veins?
bigger lumen than arteries. (hole)
contain valves.
what are the properties of red blood cells?
their job is to carry oxygen from the lungs to cells.
biconcave disc. (large surface area)
no nucleus. (more room for oxygen)
red pigment called haemoglobin. (binds to oxygen)
what is the purpose of white blood cells?
consume microorganisms. (phagocytosis)
produce antibodies to fight microorganisms.
produce antitoxins to counter toxins.
what do platelets do?
platelets are small fragments of cells that clot blood at wounds.
what is the purpose of plasma?
a pale coloured liquid that carries most things around your body.
what is a stent and what does it do?
a stent is a tube that is inserted into an artery to keep them open and allow blood to flow.
what are the positives and negatives of stents?
stents lower the risk of a heart attack in people with coronary heart disease.
they are effective long term.
recovery from surgery is quick.
a risk of infection from surgery.
potential blood clot forming at stent. (thrombosis)
what is a statin and what does it do?
a statin is a drug that reduces the amount of cholesterol in the bloodstream.
what are the positives and negatives of statins?
reduce the risk of strokes heart disease and heart attacks.
increase the amount of beneficial cholesterol.
long term that must be taken regularly.
can cause negative side effects. (such as headaches or memory loss)
non instant effects.
what is an artificial heart?
a mechanical device that pumps blood for a person whose heart has failed. (usually temporary)
what are the positives and negatives of an artificial heart?
it is unlikely to be rejected.
surgery can lead to bleeding or an infection.
parts can wear out.
blood doesn’t flow as smoothly as real hearts.
what is a mechanical valve for the heart?
a man made valve to replace a heavily damaged biological heart valve.
what are the positives and negatives of a mechanical valve?
replacing a valve is a less drastic procedure then a heart transplant.
can have problems with blood clots.
what is artificial blood?
a blood substitute used to replace a lost volume of blood.
what is epidermal tissue?
a tissue that covers the whole plant with a waxy cuticle.
what is a palisade mesophyll?
column like part of the leaf where most photosynthesis happens.
what is spongy mesophyll?
tissues with big air spaces for gas diffusion.
what is xylem and phloem?
tissues that transport resources around a plant.
what is meristem tissue?
found at growing tips of shoots and roots and can differentiate into other plant cells.
what are phloem tubes and what do they do?
columns of elongated living cells with pores in the end walls to allow cell sap through.
they transport food substances made in the leaves to the rest of the plant.
translocation in both directions.
what are xylem tubes and what do they do?
made of dead cells joined end to end with no walls between them.
strengthened with lignin.
they transport water and mineral ions from the roots to the rest of the plant.
transpiration stream only up.
what is the transpiration stream.
the loss of water from a plant.
water evaporates from stomata and more water is drawn up through the roots.
what effects the transpiration rate?
light intensity - stomata close as it becomes darker so water can’t escape.
temperature - water particles have more energy with heat.
air flow - with no airflow water particles dwell outside the leaf.
humidity - humid air already has water in it.
how are guard cells adapted to open and close stomata?
guard cells are kidney shaped.
when they are full of water (turgid) the stomata opens.
when they have little water (flaccid) the stomata closes.
