General Flashcards
Describe the roles of the diaphragm and the inter-costal muscles in ventilation?
The diaphragm and inter-coastal muscles contract; diaphragm moves down, the intercostal muscles’ contraction causes the ribcage to move upwards and outwards, thus the volume of the thoracic cavity is increased, decreasing the pressure inside the lungs. Air is forced into the lungs due to low pressure. Then, the diaphragm and the inter-coastal muscles relax, pushing air out.
How do organisms respond to changes in their environment?
Organisms have control systems which need a stimulus to operate –> receptors detect the change in the environment stimulus
effectors execute responses to the detected stimuli
What is the response of cells in roots and stems to high concentrations of auxins?
cells in roots grow less
cells in stems grow more
What are phototropism and geotropism results of?
uneven distribution of auxin in the tips of roots and stems
response of roots to light?
as a response to light, auxin accumulates on the shaded side of the roots, causing the shaded side of the root to undergo less cell elongation and division, causing the root to grow away from light.
Response of roots to gravity?
In a plant lying horizontally on the ground, auxin accumulates in the bottom half of the roots; cells in the bottom half of the roots undergo less cell elongation and division, thus the upper half grows more and the root grows in the direction of the force of gravity
Role of neurotransmitters at synapse?
Neurotransmitters are chemical messengers that are released from the presynaptic neuron into the synapse. They then diffuse across the synapse and bind to receptors in the postsynaptic neuron, stimulating a new electrical nerve impulse. Finally the chemical messengers are absorbed back into the presynaptic neuron, ready to be used again; as levels of chemical messengers in the synapse decline, the stimulation of the postsynaptic nerve ends.
What do energy requirements vary with?
activity levels(exercise), age, pregnancy, mass
how are alveoli adapted to their function? adaptation 1
They are surrounded by networks of capillaries, and thus have a large blood supply. This means gases can diffuse between the respiratory system and the blood stream easily and be absorbed at a faster rate.
how are alveoli adapted to their function? adaptation 2
They further increase the surface area of the lung, allowing more gas exchange to occur at once, thus increasing the rate of absorption
how are alveoli adapted to their function? adaptation 3
Alveoli as well as the capillaries surrounding them are one-cell thin, which means the surface across which diffusion has to occur is very short, rendering the rate of diffusion higher.
how are alveoli adapted to their function? adaptation 4
Alveoli have a moist inner lining which causes gases to dissolve in the moisture and diffuse more effectively and easily.
role of skin in high temperature regulation?
sweat glands secrete more sweat onto the skin, causing more heat to dissipate with the sweat evaporating off the skin.
blood vessels dilate, causing warm blood to be diverted to capillaries near the skin and more heat to be lost to the air through radiation
erector muscles relax and body hair flattens. This gets rid of air pockets in order to decrease temperature.
concentration of oxygen and carbon dioxide in the air compared to in the alveoli?
air is richer in oxygen than alveoli because oxygen in the alveoli diffuse into the bloodstream.
conversely, alveoli are richer in carbon dioxide because carbon dioxide diffuses from the blood stream into the alveoli.
adaptations of red blood cells?
They are small which allows them to pass through narrow blood vessels
no nucleus –> this allows more hemoglobin to be contained.
A bi-concave disc shape –> to maximise the surface area for oxygen absorption
Contain Haemoglobin which oxygen binds to –> has high affinity for oxygen, meaning oxygen particles bind to haemoglobin.
