Introduction to physiology Flashcards
What is physiology?
Science of life
What is the purpose of physiology?
- How the body works
- How living organisms adapt to different environments - e.g. temperatures, altitudes
- What goes wrong in disease (pathophysiological conditions)
- How to treat diseases
- How to maintain health
What is the process by which the internal environment is kept at a constant state?
Homeostasis
Why is the internal environment described as being ‘constant’ and not ‘equilibrium’?
As there is still energy being input into the system?
Why is the lungs, GI tract (the lumen) & urinary tract still considered part of the external environment?
As there is a layer of epithelial cells along that create a barrier.
Is the cardiovascular system and blood vessels considered part of the internal environment or the external environment?
Internal environment
What is included as extracellular fluid?
Interstitial fluid, transcellular fluid & blood plasma
What is interstitial fluid?
Fluid outside blood vessels that surrounds all of your cells
What is blood plasma?
Found within blood vessels
Why do females have a lower % body weight that is fluid?
Because women have more fat tissue, whereas men have more muscle tissue. Muscle tissue has a higher % of water content.
What is osmolality?
Total concentration of all particles that are free in a solution
What is the units used to measure osmolality?
mOsm - millisomoles per kg of water
Describe the osmolality between blood plasma, interstitial fluid & intracellular fluid
All the same
What is the advantage of the osmolality being the same between blood plasma, interstitial fluid & intracellular fluid?
Prevents movement of water into or out of the cell:
- too much water = cell would shrink
- too much water = swelling cell
Describe the sodium, chloride, potassium & calcium levels in the extracellular fluid
HIGH:
- sodium
- chloride
LOW:
- potassium
- calcium
Describe the sodium, chloride, potassium & calcium levels in the intracellular fluid
HIGH:
- potassium
- calcium
LOW:
- sodium
-chlorine
Describe how the body fluid compartments are separated (blood plasma through to intracellular)
Blood plasma - capillary endothelium - interstitial fluid - cell (plasma) membrane - intracellular membrane
Describe the features of the cell membrane
- phospholipid bilayer
- amphipathic (hydrophobic & hydrophilic parts)
- hydrophilic head (polar & interacts with water)
- hydrophobic tail (non-polar & interacts poorly with water)
What is the role of cholesterol in the cell membrane?
Regulates fluidity
Describe what 2 properties of molecules make them impermeable across the cell membrane
- Large molecules (proteins & nucleic acids)
- Charged, water soluble molecules (e.g. ions)
What type of molecule is permeable across the cell membrane?
- hydrophobic molecules
(lipid-soluble) e.g. O2, CO2 & steroid hormones
What type of molecules are partially permeable to crossing the cell membrane?
Uncharged, polar molecules (water, glucose)
- small charged molecules find it easier to enter than large charged molecules.
How do membrane proteins allow polar molecules to travel across the cell membrane?
Prevents the molecules from coming in contact with the hydrophobic core of the bilayer
What are intracellular vital parameters that are important to regulate?
- glucose
- ATP
- ions (e.g. Ca2+, K+, Na+)
- pH (H+)
What are extracellular vital parameters that are important to regulate?
- plasma levels of oxygen
- plasma levels of nutrients e.g. glucose
- plasma levels of electrolytes e.g. Ca2+, K+, Na+, H+ (pH)
What are whole body vital parameters that are important to regulate?
- arterial blood pressure
- blood volume
- core temperature
Describe the relationship between blood volume & blood pressure
More blood volume = higher blood pressure
What are the 4 features of a negative feedback loops?
- Receptors
- Control center
- Output signal
- Effector
Describe the role of receptors in negative feedback loops
Sense the vital parameter (input)
Describe the role of the control center in negative feedback loops
Compares input against a SET POINT (usually found in hypothalamus & brain stem)
Where is the SET POINT in the control center (regarding negative feedback of vital parameters)?
Hypothalamus & brain stem
Describe the role of the output signal in negative feedback loops
Signal from control center to effector (can use neural mechanisms/endocrine mechanisms e.g. hormone)
What 2 mechanisms can be used as an output signal?
- Neural mechanisms
- Endocrine mechanisms
Describe the role of the effector in the negative feedback loops
Enables a change to return vital parameter
What can an effector act on in order to return vital parameter?
Glands
What is extrinsic regulation?
Regulation via neural mechanism (brain) or endocrine system (e.g. hormones).
What is intrinsic regulation?
Cells can switch genes on and off as a form of intrinsic regulation
