BIOL240W Exam 1 Flashcards
How do we know plants have evolved independently from a unicellular common ancestor?
Similarities are due to convergent evolution
Human physiology centers on systems, plants have similar functions but are more distributed throughout the body
Advantages that both plants and animals have regarding moving onto land
Less competitive
More CO2
Environment rich in nutrients
Unfiltered sunlight
Disadvantages that both plants and animals have regarding moving onto land
UV radiation, ozone layer
Water loss
Lack of support
How did plants/animals respond to water loss disadvantage?
Plants had to form a waxy cuticle
Animals developed protective skin
How did plants/animals respond to lack of support system?
Skeletal structures and vascularity
Eukaryotes likely originated by endosymbiosis when
a prokaryotic cell engulfed a small cell that would evolve into a mitochondrion
All eukaryotic cells have
mitochondria
Vascularity
allowed plants on land to grow tall
Branches increased complexity, so more competition, so more evolution
Key adaptations of plants when transitioning from land to water
A transport system and cuticle layer
Homeostasis
tendency to resist change in order to maintain a stable, relatively constant internal environment
Homeodynamics
a concept that describes how living systems maintain equilibrium while constantly changing
Relates to concentration gradients
Complex biological systems are NOT ____ and require ________ __________
fixed, dynamic reguation
General steps a living organism goes through to respond to a disruption in homeostasis
Stimulus-change detected-RECEPTOR-input sent via afferent-CONTROL CENTER-output sent via efferent-EFFECTOR-response to change
Evolutionary adaptations enable more complex organisms to have
sufficient exchange with the environment via specialized surfaces that are extensively branched or folded
Positive feedback mechanism
An effector continues to stimulate a sensor so that a greater change happens
does NOT maintain homeostasis
Positive feedback mechanism example
Childbirth, nursing, blood coagulation
Negative feedback mechanism
Move back towards steady state (homeostasis)
Negative feedback mechanism example
Blood glucose, body temp
Describe the blood glucose mechanism
Insulin when high, pancreas releases insulin
Glucagon when low, pancreas releases
Body temp mechanism
Receptors:skin cells
Control center (brain) understands the stimulus
Effector causes change (sweating)
Mice would spend less or more energy on thermoregulation than a larger animal?
more energy
Water potential in plants is regulated by
negative feedback
Nucleus
Contains genetic material (DNA)
Surrounded by nuclear membrane that helps regulate transport in/out of nucleus
Mitochondria
For energy (ATP) production through cellular respiration
Have a small piece of circular DNA
Golgi apparatus
The organelle that modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles
Ribosomes
Molecular machines responsible for synthesizing proteins by translating mRNA
(made of proteins and RNA)
Endoplasmic reticulum
A network of membranes involved in protein and lipid synthesis. Can be rough or smooth
Location of translation (protein synthesis)
Cell membrane
A semi-permeable barrier that surrounds the cell, composed of a lipid bilayer with embedded proteins
Transport proteins
Proteins that assist in movement of substances across the cell membrane
Passive transport
The movement of substances across a cell membrane without the use of energy, including diffusion and facilitated diffusion
Active transport
The movement of substances against their conc gradient, requiring energy
Often involving pump protiens
Diffusion
The process by which molecules move from an area of high to low conc
Faciliated diffusion
A type of passive transport that uses transport proteins to move molecules across the cell membrane
Cell membrane structure
Hydrophobic head
Hydrophilic tails
Two layers of phospholipids
Hydrophobic
love nonpolar, not charged
Hydrophilic
love polar, water, charged
Small, polar molecules can
sneak through the core
O2 _____ easily, CO2_________ easiily
enters, leaves
Leak channels
Channel protein that is open all the time
Gated channels
Channel protein that is only open at certain times
Channel-mediated transport is an example of
facilitated diffusion
Facilitated diffusion depends on an _____, but active transport
existing energy gradient, makes the gradient
Protein pumps require what to function?
ATP
To warm up, the body
constricts blood vessels in extremities and decrease blood flow to skin (reduces heat loss)
To cool down, the body
dilates blood vessels in extremities and increases blood flow to skin (increases heat loss)
What body part regulates body heat?
Hypothalamus
Nervous system is made up of
nervous tissue
Integral membrane protein
Acts as channels, receptors, and transporters
Peripheral membrane protein
Signal transducers, facilitates interactions between cell and outside, surface association
Endocrine system is made of
glandular tissue (secretes something)
Neurotransmitters
electrical currents and chemical messages
Endocrine system is ________ than the nervous system
slower because it has indirect communication to target tissue
Why is the nervous system reactions so fast?
fast, direct communication to target tissue (hand/hotplate)
Neuron
nerve cell that transfer information within the body
What two types of signals do neurons use to communicate?
Electrical (long-distance)
Chemical (short-distance)
3 stages that nervous systems process information
Sensory receptor, brain and spinal cord in CNS, PNS to effector
Glial cells
insulate the axons of neurons
regulate extracellular fluid surrounding neurons
sometimes function in replenishing certain groups of neurons
Neurons make up
nervous tissue
3 characteristics of neurons
can be excited (create an electrical charge)
conductive (ability to propagate a signal)
secrete neurotransmitters
Neurons can translate an electrical signal into a
chemical signal
Cells can respond to stimuli from
environment OR other cells
Cell body (soma)
Contains one nucleus
Dendrites
short extensions off the cell body
site for receiving signals from other neurons
Axon
Extension away from the cell body
Some can be myelinated to improve conductivity
Synapse
Site of communication between neurons or between a neuron and target tissue
All neurons transmit electrical signals within the cell in
an identical manner
Connections made by active neurons are what distinguish the type of info being transmitted, how is this interpreted?
interpreting nerve impulses therefore involves sorting neuronal paths and connections
Processing of information takes place in simple clusters of neurons called __________ or the ________
ganglia, brain
no somas in the
spinal cord, only axons
Multipolar neuron
most abundant in the body
soma is at one end, dendrite at other end
Interneurons
Bipolar neuron
rare, special senses
only 2 processes extend from the body
soma is within the middle of the axon
Motor neurons ( sight, scent, hearing, taste)
Unipolar/pseudounipolar neuron
start as bipolar but develop into unipolar
mainly in PNS
Soma extends off the axon
Sensory neurons (skin, places that detect environment)
Interneurons
Conduct impulses within the CNS
Integrate sensory input or motor output
one of a chain of CNS neurons OR a single neuron connecting sensory/motor neurons
Motor neurons
Conduct impulses along efferent pathways from the CNS to an effector (muscle/gland)
Sensory neurons
Special sense organs
Conduct impulse along afferent pathways to CNS for interpretation
Ganglia of most cranial nerves
Neuroglia
Nervous tissue is made up of neurons and supporting cells called neuroglia
Neuroglia include oligodendrocytes, schwann cells, microglial, ependymal=
What role do oligodendrocytes and schwann cells play?
Myelination of axon
Nerve
collection of axons
Ganglion
collection of the cell bodies
Central nervous system
where integration takes place, brain and a nerve cord
Peripheral nervous system
carries information into and out of the CNS
Neurons of the PNS, when bundled together, form nerves
Chemical gradient
uneven distribution of molecules
electrical gradient
uneven distribution of charges
Movement of ions through protein channels will be driven by the chemical gradient and electrical gradient. Explain
Chemical (diffusion)
Electrical (attraction of repulsion of charges)
Resting membrane potential
-70mV
Change in membrane potential is called
action potential
The lipid bilayer membrane that surrounds a neuron is impermeable to ions because
ions must pass through ion channels (proteins) spanning the membrane
K+ wants to
exit the cell more
Na+ wants to
go into the cell
Inside the cell concentrations
High K+
Low Na+
Outside the cell concentrations
High Na+
Low K+
the ICF is
more negative than the ECF
ECF
extracellular fluid
Ligand-gated ion channel
Ion channels that change structure in response to a chemical binding to a receptor (ligand example: neurotransmitter)
3 main cellular events that contribute to the negative resting membrane potential of neurons
sodium potassium pump function, variable permeability of ions, anions trapped in the cell
Voltage-gated ion channel
Response to voltage changes
Charge inside cell minus charge outside cell
membrane potential
Gradient is maintained by sodium-potassium pump actively transports
Na+ outside the cell and K+ inside the cell
There are typically more K+ ________
leak channels than Na+ leak channels
Sodium potassium pump concentrations
3 sodium, 2 potassium
The cell is more permeable to
potassium
More K+ leaks out than the Na+ leaks in
Sensor
Primarily nerve cells with endings in your skin and brain
Control center
Location in an organism that processes information received from sensors
Effectors
Activated to oppose the stimulus that is causing the disruption to homeostasis
Evaporation of sweat leads to cooling of the body surface. This is an example of
negative feedback regulation
Plants and animals underwent major evolutionary changes to make the move to land but some of these changes have similarities. However, these changes were made independently of each other. This concept is called
convergent evolution
As is with regulating temp in humans, water potential in plants is regulated by a signal transduction pathway and a negative feedback loop
True
Afferent neuron
sensory neurons that carry nerve impulses from the sensory stimuli towards the CNS and brain
Efferent neuron
motor neurons that carry neural impulses away from the CNS and towards muscle to cause movement
An action potential travels from
axon hillock to axon terminal
Ventral root
Helps to transmit information from the spinal cord to the extremities of the body
The soma of pseudounipolar neurons is found in the
dorsal root ganglion
Signals being transmitted by neurons in a circuit enter the spinal cord via the
dorsal root and exit the spinal cord via the ventral root
Ogliodendrocytes are primarily located in the
white matter of the brain and spinal cord
Rules of ion movement in establishing the membrane potential
Ions move from high to low conc
Ions also move away from like charges and towards opposite charges
Depends on the permeability of the membrane
Why did plants/animals move to land?
Oxygen was dropping in the water
Ectotherm
cold-blooded
Endotherm
warm blooded
All or none law
Must fully pass the threshold to have action potential
Sub-threshold stimuli will NOT produce an
action potential
Refractory period
Period when action potential CANNOT occur
Ion cannot respond to any other stimuli
Afferent and efferent neurons are located completely within the
PNS
ICF is more negative on the inside due to
Losing positively charged ions (K+) via leak channels is the number one way that ICF becomes neg
The constantly working Na+/K+ pump
Charged proteins and DNA (DNA in a cell is always in complex with proteins, DNA itself has a negative charge)
Opening of voltage gated ion channels in the plasma membrane converts
chemical potential to electrical potential and results in an action potential
Vesicle transport moves
down the axon to the synapse and uses microtubules
Secretion
Process of converting the electrical signal of the presynaptic neuron to a chemical signal in the synapse and then back to an electrical signal in the postsynaptic neuron
Describe the 4 steps of a chemical synapse
1) An action potential arrives, depolarizing the presynaptic membrane
2) The depolarization opens voltage-gated channels, triggering an influx of Ca2+
3) The elevated Ca+ conc causes synaptic vesicles to fuse with the presynaptic membrane, releasing neurotransmitter into the synaptic cleft
4) The neurotransmitter binds to ligand-gated ion channels in the postsynaptic membrane
When Na+ enters the cell, ICF
becomes more positive, then action potential fires
Summation
One component of integrations
Interneurons and motor neurons receiving information from multiple cells and then adding the change to determine if an action potential is initiated
Two categories of postsynaptic potentials
Excitatory -> Toward threshold of action potential
Inhibitory -> Moves membrane potential away from threshold
A single EPSP is usually too
small to trigger an action potential in a postsynaptic neuron
Depolarization of postsynaptic neuron
EPSP
Hyperpolarization of postsynaptic neuron
IPSP
