Homeostasis and cells Flashcards
(39 cards)
What is homeostasis?
Means staying the same
- Avoiding change caused by internal processes inherent to the body
- Avoiding change driven by external factors
What are two laws of thermodynamics to know?
- Ordered things tend to become disorded over time
- These losses of order are irreversible.
How much energy is locked up in a ATP molecule and what did this result in?
Each ATP molecule has 0.3eV
This has resulted in many reactions evolved to need 0.3eV or 0.6eV ect to drive them
How is glucose broken down?
Oxidising a molecule of glucose releases 29eV of energy, so many mini reactions are needed to break down glucose and release energy to synthesise ATP.
Some steps pass this energy direct to ATP, whilst some pass it to intermediate carriers such as NADH.
What is the molecule that stops the bilayer from freezing up and becoming stationary?
Cholesterol, has a slightly different kinked shape so the bilayers cannot freeze up.
What can directly diffuse over the membrane
hydrophobic molecules- CO2, oxygen, testosterone and aspirin. Steriods too
What is the name of the protein that transports water over the cell membrane?
Aquaporin
What 3 types of passive protein transporter is there?
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What happens in the NA-K-ATPase pump?
In the sodium-potassium-ATPase, 3 sodium ions exit, 2 potassium ions enter and ATP is broken down in ADP and Pi
The passive transportation of sodium back into the cell pulls glucose in with it, which should be active transport but isnt.
As there is not a balance of charge moving through the pump, it creates a electro-chemical gradient (voltage)
What is the electron transport chain?
NADH gives up electrons and hydrogen ions to the transport chain, which get passed along connecting protein complexes embedded in the mitochondria membrane
The electrons pass their energy to these proteins, allowing hydrogen ions to be pumped across the membrane
When the ions return through ATPsynthase they provide the energy to synthesise ATP
Contain cytochromes which are often drug targets
Takes place in the mitochondria
What parts of the phospolipid bilayer are hydrophobic and hydrophilic?
What is an autocrine signal?
Autocrine signaling is a form of cell signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on that same cell, leading to changes in the cell.
What are the 3 types of paracrine singalling?
All from one cell to another
Juxtacrine- between adjacent cells, A communicating junction links the intracellular compartments of two adjacent cells
Endocrine- the signaling molecules (hormones) are secreted by specialized endocrine cells and carried through the circulation to act on target cells at distant body sites
Paracrine- a cell produces a signal to induce changes in nearby cells, altering the behaviour of those cells
What cannot cross the phospolipid bilayer?
Neurotransmitter, ions and insulin
What 3 components does the signalling triangle have?
Sensitivity, speed and energy efficiency
What is an open and closed loop response?
Human bodies work as a ‘closed loop’ where a receptor detects something is not ideal, an act takes place to eg warm the body up and then the act will stop when the receptor has detected the temperature is right.
A ‘open loop’ eg a heater keeps warming up even when the temperature is right.
What is the main component of the cell membrane?
Phospholipids
What cell organelle is the major site of production adenosine triphosphate (ATP)?
Mitochondria
What does the integumentary system consist of?
Comprises of the skin, hair and nails
What percent of cells are red blood cells?
84% of cells
What do phospholipids consist of?
Hydrophobic tails and hydrophilic heads.
What is the cytoskeleton?
A network of protein fibres, it gives the cell shape and allows it to move.
What are the two types of endoplasmic reticulum?
The SMOOTH synthesises lipids and hormones
The ROUGH is studded with ribosomes and responsible for protein synthesis.
What is the Golgi apparatus?
A stack of membrane sacks, role is to export proteins from the cell. When protein is received from the ER they are packaged into vesicles, then expelled using exocytosis.
