membranes/homeostasis/feedback Flashcards
What is diffusion?
The movement of molecules from an area of high concentration to low concentration.
What does passive transport require?
No energy.
Define simple diffusion.
The net movement of molecules from an area of low concentration to an area of high concentration without the facilitation of any transport proteins or carrier molecules.
What is facilitated diffusion?
Diffusion that occurs with the help of transport proteins, requiring no energy.
What is an example of facilitated diffusion?
Movement of molecules through a gated channel with the help of a hormone binding to the protein.
What is active transport?
Transport that goes against the concentration gradient, requiring energy.
What role does ATP play in active transport?
It binds to proteins to provide energy for moving substances against the concentration gradient.
What is endocytosis?
The process in which cells bring materials from outside to inside by forming vacuoles around them.
What is exocytosis?
When a material exits a cell as a vacuole merges with the cell membrane.
What are the two main molecules involved in the selectively permeable membrane?
- Phospholipids
- Membrane-spanning proteins
What is the function of cholesterol in the cell membrane?
Acts as thermal protection and maintains the shape of the cell membrane.
What are integral proteins?
Membrane-spanning proteins involved in facilitated transportation.
What is osmosis?
The diffusion of water.
Define isotonic solution.
When extracellular and intracellular solutions have the same concentration of solute.
What happens to a cell in a hypertonic solution?
Too much water will leave the cell, causing it to shrivel up.
What happens to a cell in a hypotonic solution?
Water will enter the cell, causing it to swell and potentially burst.
What does homeostasis mean?
To maintain a steady, stable state.
What role does the hypothalamus play in homeostasis?
It controls body temperature, hunger, thirst, blood pressure, fatigue, and sleep.
What is a feedback mechanism?
A process that responds to a change in the internal or external environment.
What are homeostatic cycles?
- Change in conditions
- Stimulus
- Receptor/Sensor
- Control center
- Effectors
- Homeostasis preserved
What are negative feedback loops?
Processes that counteract changes detected to maintain homeostasis.
Give an example of negative feedback.
Insulin release to decrease blood glucose levels.
What are positive feedback loops?
Processes that amplify detected changes and are not homeostatic.
What is an example of positive feedback?
- Childbirth
- Fever
- Cancer cell growth
- Injury response
Fill in the blank: In the dialysis tubing lab, the tube was permeable to ______, IKI, and water, but not starch.
glucose
