animal physiology: responding to stimuli Flashcards
Responding usually takes three steps:
Senses to detect
Interpret analyze and decide what to do
systems that can cause change
All of life strives for
homeostasis
What are some factors that can affect homeostasis
pH, temperature, O2 and CO2 levels, glucose
What are some systems that can contribute to homeostasis
- respiratory and cardio- levels of CO2 and O2
- renal- kidneys and bladder, controls water amounts
- gastrointestinal- blood sugar
- nervous and endocrine- controls all three, main controller of homeostasis
Negative feedback
most common, corrects the original stimulus
Name the pathways of negative feedback and the process
variable –> sensor –> comparer –> reference input (good match) or controller (bad match)
If they signal is sent to the controller and is a bad match it is sent back to the
original variable
negative feedback restores homeostasis in the
opposite direction
Positive feedback
less common, increases original stimuli
give two examples of positive feedback
- giving birth- increases contractions will cause birth
2. fever- increasing body temp fights infections
Name the two types of stimuli
external and internal stimuli
external stimuli are also called
exteroceptors
external stimuli
face out, the five senses, respond to the external environment
internal stimuli are also called
interoceptors
internal stimuli
face in, blood pressure, body temp
Name the four types of receptors
- chemoreceptors
- mechanoreceptors
- photoreceptors
- thermoreceptors
the nervous system is composed of two parts
Central nervous system- brain and spinal cord
Peripheral nervous system- nerves and ganglia
the CNS is _____ and the PNS is ____
internal, external
neurons are living ____. They contain the ___, ____, ___. Give the function of each
cells
cell body- nucleus and ER, takes signals in and sends them down
axon- sends info out
dendrites- receives info in
axon terminals
ends of neurons that signal to others
synapse
very small gap between the axon of one neuron and the dendrites of another
Name the four types of neurons
- bipolar- the most common, receives info and makes decisions
- unipolar- cell body not in line, quick response, hot pan example
- multipolar- multiple dendrite sites
- pyrimdal- brain and memory storage, long dendrites
The function of sensory neurons
send info from sensory receptors to CNS
the function of interneuron neurons
info from CNS to the motor neurons
motor neurons function
CNS impulses to effector (gland or muscles)
Name the four functions of neurons
- Collect info- from internal or external
- Make decisions- pass along or ignore
- Transmit Info-product signals
- Transfer info- tells sweat glands to sweat for example
Neurons transmit info by producing signals ____
electrochemically
The first Neuron function experiment results showed that
no matter how much voltage or juice, the squid leg will always produce the same action potential maximum
In the first experiment, explain the charge within the membrane
starts at negative in resting potential, shoots up to positive charge, then ends in more negative than resting potential value at one point
threshold definition
amount of stimulation needed for action potential to occur
all or nothing principle
the action potential will always fire at its maximum or nothing at all, regardless of the voltage given
resting potential
axon not conduction a nerve impulse
when the squid leg was at resting potential the charge was
negative because the sodium ions could not get in and potassium ions could not get out through the blocked plasma membrane
action potential
rapid change in axon that causes a nerve impulse
the action potential is what caused the
sodium gates to open
action potential causes ______.
depolarization- change in electronegativity
once the sodium gates opened up
potassium remains, sodium rushes in, more ions within so positive membrane
repolarization
opens the potassium gate
once the potassium gate is opened
potassium leaves the membrane and sodium remains in the membrane
how can the potassium ions leave through the opened gates
by the increased level in positive ions
after potassium is released and sodium remains inside,
the gates are both blocked off, and resting potential is restored for the process to be repeated and another neuron can fire
hyperpolarization
voltage drops lower and more negative than the voltage reading at resting potential
hyperpolarization allows
the potassium and sodium concentrations to build back up on both sides of the membrane
the second neuron experiment results shows that
two volt meters were connected, shows that neurons process one signal at a time and at different times
what are three ways to generate an action potential without electric stimulation
- spontaneous generation- randomly opens the gates of potassium and sodium
- receiving info from firing neuron- most common
- sensory receptors- what starts it all
the function of neurotransmitters
to send the information across the synapse gap
neurotransmitters are stored in
the axon terminals
two parts to the synapse
presynaptic membrane- sending neuron
postsynaptic membrane- receiving neuron
the _____ in the muscles causes action potential
contraction
the third neuron functioning experiment showed that
the maximum value of the action potential does not increase, by frequency increases and firing is more rapid
the fourth neuron functioning experiment showed that
neurons get fatigued and will stop signaling after a while, this is a good thing
sensory adaptation
presence of constant stimulation= less sensitive receptor= excitement rate slows
