coordination and response in humans and plants Flashcards
what is homeostasis?
homeostasis is the maintenance of a constant internal environment.
examples:
- body water content
- body temperature
what is required for a coordinated response?
- a stimuli (to trigger the need for a response)
- a receptor (detects the change in environment)
- an effector (carries out the physical response
what are the two different control systems in the body?
hormonal system
nervous system
what are the key differences between these systems?
hormonal system:
- longer lasting effects
- slower to trigger physical response
- carried through chemicals in the blood
nervous system:
- short term effects
- physical response triggered extremely quickly
- carried as electrical impulses through neurons throughout the CNS and PNS
what is the CNS and the PNS and what’s the difference?
CNS - central nervous system
PNS - peripheral nervous system
Anatomically speaking, the CNS is made up of the brain and the spinal cord; the PNS is made up of all the nerves travelling from the CNS to all the organs in your body, from the skin on your scalp to the tip of your toes.
From a functional perspective, the CNS is the core processing unit, receiving inputs, processing them and initiating an output signal. The PNS is the carrier of this input and output information, from the CNS to the rest of your body. There are also two aspects to the PNS, a motor and sensory system.
what happens when a receptor detects a stimuli?
a receptor in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses
what are synapses and how do they work?
a synapse is a gap between two neurons. when an electrical impulse reaches this gap, neurotransmitters are released as chemical signals. these are able to diffuse across the synaptic gap and bind to receptors on the end of the other neuron. this chemical signal from the neurotransmitters is converted to an electrical impulse which continues its path along the next neuron.
what happens if a finger comes into contact with heat (eg candle)
the stimuli is detected by a sensory neuron which sends electrical impulses to a relay neuron which quickly transfers these electrical impulses to a motor neuron. this motor neuron triggers a physical response in the body eg. moving finger away from heat
describe the structure and function of the eye
the eye is a receptor. when the retina detects light it converts this into electrical impulses which are then sent along the optic nerve to the brain.
how do the ciliary muscles and suspensory ligaments behave depending on the proximity of an object?
when an object is closer:
ciliary muscles contract
suspensory ligaments slack
lens becomes thicker and light is refracted more
how do radial and circular muscles behave depending on the amount of external light?
in dim light:
radial muscles contract
circular muscles relax
pupil dilates so more light is let in
what is vasolidation
Vasodilation is a response to being too hot. The process includes the widening of blood vessels at the skin surface to increase heat loss through the surface of the skin.
