（一）Functional Anatomy of the Retina
... is able to "generate" action potentials in the region of the receptor cell that has voltage-sensitive channels. However, not all receptors have voltage-sensitive channels. In receptor cells incapable of generating action potentials (typically specialized receptors such as the cones and rods of the r ...
... is able to "generate" action potentials in the region of the receptor cell that has voltage-sensitive channels. However, not all receptors have voltage-sensitive channels. In receptor cells incapable of generating action potentials (typically specialized receptors such as the cones and rods of the r ...
resting potential
... are equal and opposite, and the resting potential across the membrane remains steady ...
... are equal and opposite, and the resting potential across the membrane remains steady ...
Chapter 48
... are equal and opposite, and the resting potential across the membrane remains steady ...
... are equal and opposite, and the resting potential across the membrane remains steady ...
Ion Channels and Electrical Activity
... selectivity, i.e. the hydrated K+ just fits into the channel and the hydrated Na+ is too big to fit. However, how do we explain the +/- sodium channel selectivity? A selectivity filter exists inside the channel ...
... selectivity, i.e. the hydrated K+ just fits into the channel and the hydrated Na+ is too big to fit. However, how do we explain the +/- sodium channel selectivity? A selectivity filter exists inside the channel ...
The Nervous System: Neural Tissue
... A. Nerve cells are able to transmit signals due to their properties of 1. Irritability – responding to a stimuli 2. Conductivity – able to carry an impulse down its length B. The Electrochemical gradient & the Resting Potential 1. The energy for an impulse is supplied by the neuron. 2. Neurons creat ...
... A. Nerve cells are able to transmit signals due to their properties of 1. Irritability – responding to a stimuli 2. Conductivity – able to carry an impulse down its length B. The Electrochemical gradient & the Resting Potential 1. The energy for an impulse is supplied by the neuron. 2. Neurons creat ...
Cell Transport webquest
... 1. This time click on active transport & define the process: active transport 2. Why is active transport necessary? 3. Cells must expend ATP (energy) to transport materials ____________________ their concentration gradient (i.e. from _________________ to _________________ concentration). 4. Click to ...
... 1. This time click on active transport & define the process: active transport 2. Why is active transport necessary? 3. Cells must expend ATP (energy) to transport materials ____________________ their concentration gradient (i.e. from _________________ to _________________ concentration). 4. Click to ...
Nervous System - IB BiologyMr. Van Roekel Salem High School
... neuron, creating a current/initial impulse • If current is strong enough, protein channels (voltage-gated channels) open Na+ diffuse in and K+ out of axon via because of concentration gradient • Depolarization of adjacent sections of neuron occurs. Diffusion of ions results in continuing nerve impul ...
... neuron, creating a current/initial impulse • If current is strong enough, protein channels (voltage-gated channels) open Na+ diffuse in and K+ out of axon via because of concentration gradient • Depolarization of adjacent sections of neuron occurs. Diffusion of ions results in continuing nerve impul ...
nerve impulse
... calcium ions (Ca++) to diffuse into the knob rapidly Increased Ca++ concentration triggers the release of neurotransmitter by exocytosis Neurotransmitter molecules diffuse across the synaptic cleft and bind to receptor molecules, causing ion channels to open Opening of ion channels produces a pos ...
... calcium ions (Ca++) to diffuse into the knob rapidly Increased Ca++ concentration triggers the release of neurotransmitter by exocytosis Neurotransmitter molecules diffuse across the synaptic cleft and bind to receptor molecules, causing ion channels to open Opening of ion channels produces a pos ...
Neural and Hormonal Communication
... produce electric signals when excited • Terms to know – Polarization – Depolarization – Repolarizatin – Hyperpolarization psypost.org ...
... produce electric signals when excited • Terms to know – Polarization – Depolarization – Repolarizatin – Hyperpolarization psypost.org ...
Chapter 7 III. Cell Boundaries
... results in a cell bursting – Bursting not so much a problem in larger organisms….tend to be in isotonic environments • Osmotic pressure may not allow a plant or bacterial cell to burst , but could weaken the cell wall hypertonic ...
... results in a cell bursting – Bursting not so much a problem in larger organisms….tend to be in isotonic environments • Osmotic pressure may not allow a plant or bacterial cell to burst , but could weaken the cell wall hypertonic ...
Cell Transport 2016 - Waterford Public Schools
... 1. Concentration gradient- the higher the concentration, the faster it diffuses. • But, if the concentration gradient is too high, because of the momentum, the movement may not be able to stop and the cell will burst. 2. Distance- more rapid diffusion over shorter distances ...
... 1. Concentration gradient- the higher the concentration, the faster it diffuses. • But, if the concentration gradient is too high, because of the momentum, the movement may not be able to stop and the cell will burst. 2. Distance- more rapid diffusion over shorter distances ...
Chapter 10
... An action potential occurs at a specific site. When an action potential occurs at the trigger zone of a nerve cell, it sends an electrical impulse to the adjacent membrane. This causes an action potential at the next site. This occurs in a wavelike sequence, without losing amplitude, from the beginn ...
... An action potential occurs at a specific site. When an action potential occurs at the trigger zone of a nerve cell, it sends an electrical impulse to the adjacent membrane. This causes an action potential at the next site. This occurs in a wavelike sequence, without losing amplitude, from the beginn ...
2014 Quiz IA Answers
... Boundaries separating the internal environment from the outside world Mechanisms that permit cells to ingest food Biochemical pathways that permit energy stored in complex molecules to be released The capacity to reproduce Ability to respond to stimuli in the natural world ...
... Boundaries separating the internal environment from the outside world Mechanisms that permit cells to ingest food Biochemical pathways that permit energy stored in complex molecules to be released The capacity to reproduce Ability to respond to stimuli in the natural world ...
Section 7.3 Cell Transport
... Plasmolysis - In a hypertonic environment, water leaves the cell and the cell shrinks away from the cell wall as turgor pressure is lost ...
... Plasmolysis - In a hypertonic environment, water leaves the cell and the cell shrinks away from the cell wall as turgor pressure is lost ...
Cells and Their Environment - Coach Blair`s Biology Website
... • They bond and drag molecules through the lipid bilayer and release them on the opposite side. ...
... • They bond and drag molecules through the lipid bilayer and release them on the opposite side. ...
Document
... Ans: The free-energy changes of the individual steps in a pathway are summed to determine the overall free-energy change. Thus, a step that might not normally occur can be driven if it is coupled to a thermodynamically stable reaction. Section: 15.1 25. If many compounds are common to both anabolic ...
... Ans: The free-energy changes of the individual steps in a pathway are summed to determine the overall free-energy change. Thus, a step that might not normally occur can be driven if it is coupled to a thermodynamically stable reaction. Section: 15.1 25. If many compounds are common to both anabolic ...
Chapter 48
... the action potential there. To the left of this region, the membrane is repolarizing as K+ flows outward. ...
... the action potential there. To the left of this region, the membrane is repolarizing as K+ flows outward. ...
Membrane potential
Membrane potential (also transmembrane potential or membrane voltage) is the difference in electric potential between the interior and the exterior of a biological cell. With respect to the exterior of the cell, typical values of membrane potential range from –40 mV to –80 mV.All animal cells are surrounded by a membrane composed of a lipid bilayer with proteins embedded in it. The membrane serves as both an insulator and a diffusion barrier to the movement of ions. Ion transporter/pump proteins actively push ions across the membrane and establish concentration gradients across the membrane, and ion channels allow ions to move across the membrane down those concentration gradients. Ion pumps and ion channels are electrically equivalent to a set of batteries and resistors inserted in the membrane, and therefore create a voltage difference between the two sides of the membrane.Virtually all eukaryotic cells (including cells from animals, plants, and fungi) maintain a non-zero transmembrane potential, usually with a negative voltage in the cell interior as compared to the cell exterior ranging from –40 mV to –80 mV. The membrane potential has two basic functions. First, it allows a cell to function as a battery, providing power to operate a variety of ""molecular devices"" embedded in the membrane. Second, in electrically excitable cells such as neurons and muscle cells, it is used for transmitting signals between different parts of a cell. Signals are generated by opening or closing of ion channels at one point in the membrane, producing a local change in the membrane potential. This change in the electric field can be quickly affected by either adjacent or more distant ion channels in the membrane. Those ion channels can then open or close as a result of the potential change, reproducing the signal.In non-excitable cells, and in excitable cells in their baseline states, the membrane potential is held at a relatively stable value, called the resting potential. For neurons, typical values of the resting potential range from –70 to –80 millivolts; that is, the interior of a cell has a negative baseline voltage of a bit less than one-tenth of a volt. The opening and closing of ion channels can induce a departure from the resting potential. This is called a depolarization if the interior voltage becomes less negative (say from –70 mV to –60 mV), or a hyperpolarization if the interior voltage becomes more negative (say from –70 mV to –80 mV). In excitable cells, a sufficiently large depolarization can evoke an action potential, in which the membrane potential changes rapidly and significantly for a short time (on the order of 1 to 100 milliseconds), often reversing its polarity. Action potentials are generated by the activation of certain voltage-gated ion channels.In neurons, the factors that influence the membrane potential are diverse. They include numerous types of ion channels, some of which are chemically gated and some of which are voltage-gated. Because voltage-gated ion channels are controlled by the membrane potential, while the membrane potential itself is influenced by these same ion channels, feedback loops that allow for complex temporal dynamics arise, including oscillations and regenerative events such as action potentials.