Plz explain these questions in detail for me! will thumbs up! 4) Give the definition of graded potentials and explain the differences between graded potential and action potential. 5) Explain how action potentials are generated and transmitted along axons. Explain what happens to the activity of different ion channels 6) Provide the definitions of extracellular environment, body fluids, and extracellular matrix. 7) Give the definitions of carrier-mediated transport and facilitated diffusion
The Correct Answer and Explanation is:
4) Definition of graded potentials and differences from action potentials
A graded potential is a small, localized change in the membrane potential of a neuron. It usually occurs in the dendrites or cell body as a response to a stimulus, such as a chemical neurotransmitter. These potentials vary in strength depending on the intensity of the stimulus and decrease as they travel across the membrane.
The main differences between graded and action potentials are:
- Graded potentials are variable in size and can be either depolarizing or hyperpolarizing. They do not follow the all-or-none principle and decay with distance.
- Action potentials, in contrast, have a fixed size and always follow the all-or-none principle. Once triggered, they do not decrease in strength and are propagated along the axon without loss.
Graded potentials help initiate action potentials if the threshold is reached at the axon hillock.
5) Generation and transmission of action potentials and ion channel activity
An action potential is a rapid, brief electrical signal that travels along the axon. It is generated when a neuron’s membrane potential reaches a specific threshold.
The process involves several steps:
- Depolarization: When a stimulus is strong enough, voltage-gated sodium (Na⁺) channels open, allowing Na⁺ to enter the neuron. This influx causes the inside of the cell to become more positive.
- Repolarization: After reaching a peak, Na⁺ channels close and voltage-gated potassium (K⁺) channels open. K⁺ exits the cell, returning the membrane potential to a more negative value.
- Hyperpolarization: K⁺ channels may stay open too long, causing the membrane to become slightly more negative than the resting potential.
- Restoration: The sodium-potassium pump (Na⁺/K⁺ ATPase) helps restore the original ion balance by pumping Na⁺ out and K⁺ in.
This signal is transmitted down the axon by opening adjacent voltage-gated channels, creating a wave of depolarization.
6) Definitions of extracellular environment, body fluids, and extracellular matrix
- Extracellular environment refers to everything outside the cells, including the fluid and structures surrounding them. It supports cell function by supplying nutrients and removing waste.
- Body fluids are liquids within the body that include intracellular fluid (inside cells) and extracellular fluid (outside cells). The extracellular fluid consists of interstitial fluid, plasma, and other fluids like lymph and cerebrospinal fluid.
- Extracellular matrix is a complex network of proteins and carbohydrates located outside cells. It provides structural support, anchors cells, and influences cell behavior.
These components are essential for maintaining homeostasis and cell communication.
7) Definitions of carrier-mediated transport and facilitated diffusion
- Carrier-mediated transport is a type of membrane transport that involves specific proteins in the cell membrane. These proteins bind to molecules and help move them across the membrane. This process can be active (requiring energy) or passive (not requiring energy).
- Facilitated diffusion is a type of passive transport where molecules move across the membrane through carrier or channel proteins. It does not require energy and allows substances like glucose or ions to move from an area of high concentration to low concentration with the help of transport proteins.
Both processes are selective and essential for regulating what enters or exits the cell.
