Excretion (humans + plants) Flashcards
How are organisms able to respond to changes in their environment
Organisms use the nervous system that contains electric impulses that are sent from the receptor, through neurons and synapses in the body, through the (CNS), and reaches the effector which responds to the stimuli
What is homeostasis
Homeostasis is the maintenance of a consistent internal environment e.g: body water content and body temperature
what does a coordinated response require?
- A receptor (detects the stimuli)
- A stimuli (change in the environment)
- An effector (does the action to react to the stimuli)
what are the differences between hormonal and nervous communication?
Nervous:
- Form of transmission = Electrical
- Transmission pathway = Nerves
- Speed of transmission = Fast
- Duration of effect = Short term
Endocrine/Hormonal:
- Form of transmission = Hormonal
- Transmission pathway = Blood vessels
- Speed of transmission = Slow
- Duration of effect = Long term
What parts of the body does the CNS (Central Nervous System) contain?
Brain and Spinal Cord
How does a rapid response take place
- Receptors send electrical impulses into and out of the CNS and to the Effector
what are neurotransmitters and what do they do?
Neurotransmitters diffuse across a synapse carrying an electrical impulse and binds to a receptor carrying the impulse across neurons
what is a reflex arc
An extremely quick reflex to a danger that is so quick that it happens before the brain registers it. This happens as there are only three neurons and therefore only two synapses.
Explain the process of a simple reflex arc ( for this example, use the withdrawal of a finger from a hot object)
The hot object (stimuli) is received by the receptor (the finger/s) and an electric impulse is sent along a sensory neuron which is then diffused across a synapse to a relay neuron that passes through the CNS and diffuses to a motor neuron that takes the impulse to the effector, causing the action to take place (hand/finger is moved away)
What is the function and structure of the eye as a receptor
see book for what the eye does and what different parts are called
How does the eye respond to changes in light intensity
When the eye detects a light intensity that is too high the radial muscles relax and the circular muscles contact causing the pupil to dilate and become smaller so less light enters as it is more powerful. When the light is too dim, the opposite happens so more light is let in as it is less powerful
How does the eye respond to focusing on near and distant objects
When an object is close, the ciliary muscles contract and the suspensory ligaments become slack, causing the lens to become more convex and bend the light towards the fovea. Whereas when an object is far the ciliary muscles are relaxed and the suspensory ligaments are taut causing the lens to be stretched and become less convex so the light doesn’t bend as much and focuses on the fovea
what are the four ways the body regulates body temperature
1) The body releases sweat on the surface of the body (the skin), this sweat is then evaporated which uses up heat energy, and cools the body’s temperature - releases less sweat to heat the body
2) VASODILATION - widening (VASOCONSTRICTION - narrowing) - The blood vessels near the edge of the skin widen. This means that more heat radiates from the body - when the body is too cold, the blood vessels narrow so the opposite takes place
3) The hairs on the surface of the skin stand up. This causes a layer of air to be trapped on the surface of the skin between the hairs and insulate the bod. This causes less heat energy to radiate from the body to the surroundings. When the body is too hot the hairs lay flat so no air is trapped
What are the roles and effects of Adrenaline
stimulates the ‘flight or fight’ response
What are the roles and effects of Testosterone
Regulates sperm cell production
