Physio SG 2

Study guide 2

Differentiate between static and dynamic equilibrium

Dynamic equilibrium is where the rate in equals the rate out. Static equilibrium is where there is no change in movement to the system.

Describe the relationship between response to stimuli and homeostasis.

Organisms use stimuli to maintain homeostasis.

Differentiate between positive and negative feedback loops

Positive feedback loops use the output of the system as the input until the action is completed. An example of this is childbirth where hormones are release to create contractions which increases pressure and releases more hormones. A negative feedback loop’s output triggers a counter response to a set point. An example is thermoregulation to maintain homeostasis of body temperature.

Summarize the role of enzymes in the regulation of homeostasis

They regulate homeostasis by decreasing the activation energy of a reaction to control the correct rate of every reaction. This assures that the body can maintain homeostasis.

Summarize the role of cell transport in the regulation of homeostasis

Cellular transport is essential for homeostasis because the cell membrane is selectively permeable which only allows a small range of molecules. It ensures that the internal environment of the cell is highly regulated to maintain homeostasis.

Draw an example of a feedback loop

Describe the 6 types of cellular transport, including a substance transported for each

Simple diffusion: spreading of molecules across a membrane until it reaches equilibrium; oxygen. Facilitated diffusion: a transport protein acts to facilitate diffusion of molecules through a cell membrane (large and polar molecules); glucose. Osmosis: movement of water across a cell membrane (3 types: hypertonic, hypotonic, and isotonic); water. Molecular pumps: cell uses energy to pump molecules against the concentration gradient through a protein channel; sodium potassium pump. Endocytosis: uses vesicles to move large particles into cell; bacteria that are engulfed by white blood cells. Exocytosis: uses vesicles to export materials out of cell; nerve cells secreting neurotransmitters.

Explain the importance of cell signaling and communication in maintaining homeostasis. Include a brief description of a real-world examples of breakdown in cell communication and how that impacted homeostasis in the organism.

Cell signaling allows the cell to maintain homeostasis by having a dynamic equilibrium. It allows the cell to respond and process information from stimuli and talk to other cells. Can be physical or chemical stimuli. For example, with type 1 diabetes, the immune system destroys the insulin-producing cells in the pancreas. The necessary signal (insulin) is never produced, so the cells are never told to take up glucose. This leads to dangerously high blood sugar levels (hyperglycemia), as the homeostatic feedback loop is completely broken.

Draw a sketch of a signal transduction pathway, label key parts

Draw a sketch of a signal transduction pathway and label the key parts

Distinguish between the types of chemical signals that can initiate a signal transduction pathway

Autocrine signal: self signal; cell signals itself using its own produced signal. Paracrine Signal: diffuses to nearby cells. Juxtacrine: requires direct contact between signal and target cell. Hormones: Signals far targets and goes through the bloodstream.

Explain the importance of specificity in receptor proteins. Include the difference between intracellular and membrane receptors and the toes of ligands they would bind to.

Specificity is crucial for receptor proteins because it ensures that a cell responds only to the correct signaling molecule, or ligand. This "lock and key" mechanism prevents a cell from receiving and reacting to wrong signals, which could disrupt its function and lead to disease. This precision is essential for maintaining the body's homeostasis.

Describe the importance of a second messenger in certain signal transduction pathways

In signal transduction, a second messenger is a crucial, small, non-protein molecule that amplifies a signal received by a cell. They act as intracellular relay molecules that spread the initial message from a receptor at the cell surface to various target proteins within the cell. This allows the first messenger to trigger a massive and rapid response inside the cell.

Explain several types of responses that can be triggered by a transduction pathway

Transduction can trigger responses like opening of ion channels by changing ion concentration, altering gene expression (switched on: upregulated, switched off (downregulated), and alteration of enzyme activity.

Homeostasis

Homeostasis is a self-regulating process where biological systems maintain a stable internal environment using stimuli to respond to changes in the environment.

receptor

A receptor is a protein molecule on or inside a cell that specifically binds to a particular substance, known as a ligand, to initiate a physiological response.

stimulus

something that triggers a physiological or behavioral response in an organism.

Effector

a cell, tissue, or organ, such as a muscle or gland, that responds to a signal from the nervous system or hormones to carry out a specific action.

response

action or change in behavior that an organism or system carries out after detecting a stimulus.

feedback inhibition

a regulatory mechanism in which the final product of a metabolic pathway inhibits an enzyme at an earlier stage of the same pathway, preventing overproduction. This process is a form of negative feedback because the output inhibits the input

passive transport

the movement of substances across a cell membrane that does not require the cell to use energy. This process relies on a concentration gradient, where molecules naturally move from an area of high concentration to an area of low concentration until they are evenly distributed.

Active transport

the movement of molecules or ions across a cell membrane against their concentration gradient, from a region of lower concentration to a region of higher concentration, a process which requires the cell to use energy, typically in the form of ATP.

hypertonic solution

A hypertonic solution is a solution with a higher concentration of solutes and a lower concentration of water compared to another solution

hypotonic solution

a solution with a lower concentration of solutes and a higher concentration of water compared to another solution

isotonic solution

a solution with the same concentration of solutes as the inside of a cell, which results in no net movement of water across the cell membrane

ligand

a molecule that binds specifically to a receptor protein to form a complex and trigger a biological or chemical process.

signal transduction

a process where a cell converts an external signal into a series of internal molecular events (cascade), leading to a specific cellular response.

pathway

a series of interconnected molecular or biochemical reactions that occur within a cell, where the product of one reaction becomes the reactant for the next

inhibitor

a substance that slows down or stops a chemical reaction.

transduction

the process by which a sensory receptor converts a physical or chemical stimulus into an electrical signal that can be transmitted and interpreted by the nervous system.

phosphorylation

is the reversible addition of a phosphate group to a molecule to act as an "on" or "off" switch to regulate its function.

desphosphorylation

biochemical process of removing a phosphate group from a molecule, often a protein, a process catalyzed by enzymes called phosphatases, to turn off the protein.

second messenger

is a small, non-protein molecule or ion that relays and amplifies a signal received at a cell's surface to target molecules inside the cell.