Topic 11 - Coordination and response Flashcards
What is Homeostasis?
Homeostasis is the maintenance of the body’s internal environment within tolerable limits around an optimum value. e.g. temperature: 37°C is the optimum temperature for the enzymes that control metabolism.
Which organs and tissues in the human body are involved in homeostasis?
All of them
In greenhouses, when sensors detect changes in what 2 things?
In greenhouses, when sensors detect changes in temperate and light intensity, corrective measures are triggered.
When sensors detect a change from normal conditions and trigger an appropriate response? (what is this called)
this is called negative feedback.
Water content is controlled at a what level?
Water content is controlled at a cellular level.
Excess heat is lost from the human body by…
sweating
When excess heat damages enzymes they are…
denatured
Sugar content in the body is controlled by? (2)
- The release of the hormone insulin
- The activation of enzymes
Water is being controlled by what organ?
Kidney
Salt being controlled by what organ?
Kidney
Temperature being controlled by what organ?
Skin
Sugar being controlled by what organ?
Pancreas
Carbon dioxide being controlled by what organ?
Lungs
Urea being controlled by what organ?
Kidney
What is the stimulus of skin?
Temperature
What is the stimulus of tounge?
Chemical taste (in food and drink)
What is the stimulus of nose?
Chemical smells (in the air)
What is the stimulus of eyes?
Light
What is the stimulus of ear?
Sound
What is a receptor?
the thing that detect the signals
What is a stimulus?
a chemical or physical change that triggers the receptor
3 types of effectors? (3)
- a muscle contracting to move an arm
- a muscle contracting to alter pupil diameter in the eye
- a gland releasing ainto the blood hormone
What is the order of reflex action?
stimulus → receptor →sensory neurone→relay neurone→ motor neurone → effector → response
Step by step reflex action when a hand is over a candle? (5)
- Receptor cells in the skin detect a stimulus (the heat from the candle).
- Sensory neurone sends impulses to relay neurone in the spinal cord.
- The relay neurone connects to the motor neurone (and also sends a message to the brain).
- Motor neuronesends impulses to effector.
- Effectorproduces a response (muscle contracts to move hand away).
What happens when you are too hot? (sweating)
Sweat glandsin the skin release more sweat. The sweat evaporates, transferring heat energy from the skin to the environment.
What happens when you are too hot? (blood vessel)
Blood vessels leading to the skin capillaries become wider - theydilate- allowing more blood to flow through the skin, and more heat to be lost to the environment. This is calledvasodilation.
What happens when you are too cold? (hairs)
Skeletal musclesrapidly and weshiver. These contractions need energy from, and some of this is released as heat
What happens when you are too cold? (blood vessels)
Blood vessels, which lead to the skin capillaries, become narrower - they constrict – which allows less blood toflowthrough the skin and conserve the core body temperature. This is calledvasoconstriction.
What are the 7 parts of the eye? (7)
- Cornea
- Iris
- Lens
- Retina
- Optic nerve
- Pupil
- Ciliary muscle
- Suspensory ligaments
What is the function of the cornea?
Refracts light - bends it as it enters the eye
What is the function of the lens?
Further refracts light to focus it onto the retina
What is the function of the retina?
Contains the light receptors
What is the function of the optic nerve?
Carries impulses between the eye and the brain
What is the function of the pupil?
Space in the iris that allows light into the eye
What is the function of the ciliary muscles?
A ring of muscle that contracts and relaxes to change the shape of the lens
What is the function of the sensory ligament?
Ligaments that connect the ciliary muscle to the lens
What is the function of the iris?
Controls how much light enters the pupil
What is positive tropism?
Positive tropism is when a plant growstowardsthestimulus.
What does a stem respond to?
Stemresponse to light ispositive phototropism(grows towards the light).
What does a root respond to?
Rootresponse to gravity ispositive geotropism(grows in the direction of the force of gravity).
What are auxin?
Auxin is a family of plant hormones. They are mostly made in the tips of the growing stems and roots, which are the meristems. They candiffuseto other parts of the stems or roots. Auxin change the rate of elongation in plant cells, controlling their length.
How do stems and roots respond differently to high concentrations of auxin? (2)
- cells in stems grow more
- cells in roots grow less
What is Phototropisms?
In a stem, the shaded side contains more auxin andgrows longer– causing the stem to bend towards the light.
Hormones vs Nerves
