Bio Test #1 Flashcards
Homeostasis
The maintenance of constant conditions in the internal environment of and organism
What it the most important part in maintaining homeostasis?
Our cells because without proper cell functions, the body starts to shut down normal homeostatic mechanisms
Receptor
Detects any deviations from the set point and signals the change to the control centre along a neuron
Effector
Receives a signal from the control centre and causes a change to restore the set point
Control centre
Interprets the signal form the receptor and signals to the effector along a neuron
Set point
The normal homeostatic range (37C)
Negative feedback
Loops are used to control neostatic systems within a narrow range of set points
What do cells need to do to maintain homeostasis?
- Obtain food
- Convert energy
- Eliminate wastes
- Reproduce
- Grow and repair itself
- Transport substances
Fluid mosaic model
Model for the cells plasma membrane
What is plasma membrane made of?
2 layers of phospholipids
Passive transport
- Materials move from an area of high concentration to an area of low concentration.
- The materials move with the concentration gradient and does not require energy
Diffusion
Materials move from an area of high concentration to an area of low concentration
- in the cell materials will move across the membrane through specialized pores in the cell membrane
Osmosis
Water molecules that move across a selectively permeable membrane from an area of high concentration to low concentration
- water will move across the membrane through specialized pores
3 possible concentrations for a solution
- Isotonic
- Hypertonic
- Hypotonic
Isotonic
A solution with a concentration equal to the cell
Hypertonic
A solution with a high concentration
- has high osmotic pressure
- more solute than water
Hypotonic
A solution with a low concentration
- Has low osmotic pressure
- Less solute than water
Facilitated diffusion
When materials move from an area of high concentration to low concentration but requires the assistance of specialized carrier proteins in the plasma membrane.
Eg.) glucose
Active transport
Materials move from an area of low concentration to and area of high concentration. Movement is against the concentration gradient. The cell must use energy in the form of ATP to move the materials
Carrier proteins
Can move materials across the membrane AGAINST the concentration gradient
Endocytosis
Materials are engulfed by the cell and become enclosed in infoldings of the plasma membrane that eventually form vacuoles
2 forms of endocytosis
- Pinocytosis
- Phagocytosis
Pinocytosis
Small amounts of liquid brought in
Phagocytosis
Solid particles are ingested into the cell
Exocytosis
A vacuole of materials will fuse with the plasma membrane forcing contents from the cell
Factors that influence the movement of substances across a membrane:
- size of molecule
- concentration gradient
- temperature
- charge of molecules
- surface area
Thermoregulation
The ability to maintain a constant temperature
Osmoregulation
An internal balance between water and dissolved materials
Why is the model for the cells membrane called THE FLUID MOSAIC MODEL?
The plasma membrane is said to be fluid because components of the membrane can move around sideways and can rearrange itself to suit the task.
-mosaic means it’s made up of many different parts
How are phospholipids arranged so that water doesn’t seep through the walls of the cell?
There are 2 layers of phospholipids,
- hydrophilic phospholipid head (water loving)
- hydrophobic fatty acid tail (water hating)
