2 - Homeostasis Flashcards
(53 cards)
Homeostasis concept
Homeostasis is the maintenance of a stable internal environment within tolerable limits, despite external changes
Essential for physiological functions such as temperature regulation, pH balance, and ion concentrations
Regulated variable
directly controlled or regulated and for which there are specific sensors that monitor any changes
(eg. Body temperature which is specifically monitored by peripheral and central temperature receptors)
Unregulated variables
contribute to control of process but don’t have specific sensors
Negative feedback
system that detects deviations from a set point and initiates corrective actions (eg. Body temperature regulation)
Positive feedback
amplifies changes until a specific endpoint is reached (eg. Childbirth contractions) / there must be an end point at which the systems switched off and homeostasis
Factors influeincing homeostasis
Genetics / nutrition / physical activity / mental health / environmental exposure
Physically activity - effects gas usage and production —> CO2 production will affect pH and ATP use
Failure of homeostasis
Deficiency - lack of essential elements impairs biological processes
Toxicity - excess elements can disrupt cellular function
Components of cell membrane
Phospholipids bilayer
Proteins
Cholesterol
Carbohydrates
CM structure - phospholipids bilayer
hydrophilic heads face outward; hydrophobic tails face inward
CM structure - proteins
embedded in the membrane for transport, signalling, and structural support
CM structure - cholesterol
Provides membrane fluidity and stability
CM function
Controls the movement of substances in and out of the cell
Maintains homeostasis by regulating internal conditions
CM - Protein pores
Beta pleated sheets
Form a pore through the membrane (can be selective or non-selective)
Can also be known as leakage channels
Passive transport
No ATP required
Simple diffusion
movement of molecules (e.g., O₂, CO₂) from high to low concentration
Facilitated diffusion
movement via protein channels or carrier proteins (e.g., glucose transport)
Osmosis
diffusion of water through a semi-permeable membrane driven by solute concentration
RBC - why cant they withstand pressure increase
bursts due to lack of cell wall
(cant withstand the pressure increase when water moves in from hypotonic solution)
Isotonic
Equal concentration inside and outside
Hypertonic solution
Water moves out of the- shrivelled
Hypotonic solution
Water moves in - burst or swell
What’s transpiration controlled by
Concentration of a sciatic acid
Living in saline water - impermeable membranes
Prevents excess water loss
Marine organisms tend to be…
Isotonic
