multicellularity, nervous system, sensory system Flashcards
reoccuring themes of physiology
1) homeostasis
2) form and function
3) overcoming the limits of diffusion
simple multicellularity
- adhesion molecules that cause adjacent cells to stick together (colonies)
-no major specialization of communication between cells - every cell in contact with external environment
complex multicellularity
- specialized cell functions
- communication between cells
- take in info from environment -> signal -> craft response
pros of multicellularity
- longer life span
- greater efficiency of specialized cells
- sexual reproduction leads to more genetic diversity
- bigger better fit for survival
multicellularity cons
- increased energetic costs
- have to do more than just diffusion for survival
- takes longer to reach reproductive maturity
- possibility for infections
surface area: volume ratio
the smaller the animal = larger the SA: V ratio
* smaller organism -> faster molecular diffusion rate
4 types of tissues
connective, epithelial, muscular, nervous
connective tissues
fat, bone, cartilage
epithelial tissues
connectivity/ diffusion tissues
ex. gut epithelial tissues in GI tract
muscular tissue
skeletal, smooth (ex. digestive muscles), cardiac
nervous tissues
specialized cells that conduct signaling
organ
a collection of tissues that structurally form a functional unit specialized to perform a particular function
mechanisms of substance transport
diffusion and bulk transport
pathway for systems based in homeostasis
- communication of info to all different specialized cells
- translate signals into actions
- distribution of nutrients, energy and oxygen to muscles
- removal of waste
- defense immune system
homeostasis neg feedback ex
feel cold -> signal to hypothalamus -> muscles shiver -> stop signals once at right temp
nervous system
network of neurons that receive, process and transmit information
group of neurons
nerve
ganglia
collection of nerves
cephalization
concentrating sensory organs and sensory neurons at front/anterior of the body; helps sense the environment
convergent evolution
evolved independently several times
ex. cephalization
nervous system 3 step mechanism; input and output
1) sense (sensory input)
2) integrate/ process
3) coordinate response (motor output)
central nervous system
brain and spinal cord; sending and receiving messages to various parts of the body.
peripheral nervous system
part of your nervous system that lies outside your brain and spinal cord; sends info from different areas of your body back to your brain and carries out commands from your brain to various parts of your body
3 types of neurons
1) sensory neurons
2) interneurons
3) motor neurons
sensory neurons
carries sensed impulses from the receptor to the CNS
*structure: cell body can be along axon
interneurons
enables communication between sensory or motor neurons and the central nervous system; in CNS
motor neurons
carries a signal from the central nervous system (CNS) to an effector cell, which then carries out the desired response
pre synaptic neuron
sends signal
post synaptic neuron
receives signal
signal transduction steps
1) stimuli received by dendrites + cell body
2) signal goes to axon hillock to determine if signal is strong enough to fire action potential
3) signal through axon terminal -> release neurotransmitter
4) neurotransmitter bonds to post synaptic cell membrane -> new signal
axon hillock
the region of a neuron that controls the initiation of an electrical impulse based on the inputs from other neurons or the environment; is signal big enough to fire action potential?
relative charges of inside and outside of cell
inside: neg
outside: pos
is there more potassium inside or outside of the cell
inside
is there more sodium inside or outside of the cell
outside
are there more sodium or potassium channels
potassium
sodium potassium pump
moves Na+ out of the cell and K+ into the cell against the concentration gradient (active transport)
K+ equilibrium potential
-90 mV
Na+ equilibrium potential
+60 mV
resting membrane potential
the electrical potential difference across the plasma membrane when the cell is in a non-excited state.; -70 mV
what dictates the resting membrane potential of a neuron
equilibrium potential
what is used to maintain resting membrane potenial
sodium potassium pump
action potential
the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell
action potential steps
1) threshold
2) depolarization
3) repolarization
4) refractory
action potential; threshold
positive ions come into cell increasing its voltage (more pos)
action potential; depolarization
large amounts of Na+ come into the cell; large increase in + V
action potential; repolarization
large amounts of K rush out of the cell through open pore decreasing cell voltage
*once potential gets to around +40
action potential; refractory
membrane potential drops below the resting membrane potential; have to build potential back up
how are the K+ and Na+ pores opened and closed
inactivation gates
Saltatory propagation
electrical impulses along axons is highly accelerated by the myelin sheath and produces saltating or “jumping” action potentials
node of ranvier
a gap in the myelin sheath of a nerve that allow the generation of a fast electrical impulse along the axon.
synapse
end of axon terminal where chemical signals released
presynaptic membrane
end of neuron that is sending the signal; has Ca2+ channel that is opened by depolarization, Ca2+ released moves vesicles to exocytosis with membrane