B4 Organising animals and plants Flashcards
plasma
has blood cells suspended in it and transports proteins and other chemicals around the body
red blood cells
contain haemoglobin that binds to oxygen to transport it from the lungs to the tissues. They have an increased surface area and no nucleus
white blood cells
help to protect the body against infection
platelets
cell fragments that start the clotting process at wound sites
main types of blood vessels
arteries, veins and capillaries
arteries
carry oxygenated away from the heart to the organs. Thick walls and thick layer of muscle and elastic fibres
veins
carry deoxygenated blood to the heart. Blood is squeezed back towards the heart by the action of the skeletal muscles and valves prevent backflow. Relatively thin walls and a large lumen
Capillaries
huge network of tiny vessels that link the arteries and veins. Tiny vessels with narrow lumen. Walls are just a cell thick
Circulation system
humans have a double circulation system
heart valves
keep the blood flowing in the right direction
stents
use to keep narrowed or blocked arteries open
statins
reduce cholesterol levels in the blood, reducing the risk of coronary heart disease
how many chambers does the heart have?
4
ventricles
bottom chambers which pump blood out of the heart
heart process
blood comes from the veins into the atria, through the valves to the ventricles, and then out via arteries
which side of the heart is thicker?
left
damaged heart valves
can be replaced with biological or mechanical valves
resting heart rate
controlled by a group of cells in the right atrium that form a natural pacemaker
artificial pacemakers
electrical devices used to correct irregularities in the heart rhythm
artificial hearts
used to keep patients alive while they wait for a transplant or their heart to rest as an aid to recovery
ribcage
protects the lungs
diaphragm
strong sheet of muscle which separates the lungs from the digestive organs below
how are the lungs ventilated?
contraction and relaxation of the intercostal muscle between the ribs and the diaphragm
adaptations of the alveoli
they provide a very large surface area and a rich supply of blood capillaries. This means gases can diffuse into and out of the blood as efficiently as possible
epidermal tissue
covers the surface and protects the plant
palisade mesophyll
contains lots of chloroplasts, which carry out photosynthesis
spongy mesophyll
contains some chloroplasts for photosynthesis but also has big air spaces and a large surface area to make the diffusion of gases easier
xylem tissue
carries water and mineral ions from the soil around the plant to the stem and leaves. Mature xylem cells are dead.
phloem tissue
transports sugars made by photosynthesis from the leaves to the rest of the plant. Also transported to storage organs where it provides an energy store for winter. Phloem is a living tissue.
translocation
the movement of dissolved sugars from the leaves to the rest of the plant
transpiration
the loss of water vapour from the surface of plant leaves. Anything that affects the rate of evaporation also affects the rate of transpiration
transpiration stream
As water evaporates, more water is pulled up through the xylem to take its place
how is the water lost in plants?
water is lost through the stomata, which opens to let in carbon dioxide for photosynthesis. The stomata and guard cells control gas exchange and water loss
factors affecting transpiration
anything that increases the rate of photosynthesis and evaporation will increase the rate of transpiration
4 factors that affect transpiration
temperature, humidity, air movement and light intensity
controlling water loss
most of the stomata are found on the underside of leaves
what is used to measure transpiration rates?
a potometer
