Big Flashcards
Molecule definition?
2 or more atoms joined together
Compound definiton?
Molecules containing atoms of more than one element
4 types of tissue?
Epithelial
Connective
Muscular
Nervous
Stages of organism level?
Organism System Organ Tissue Cellular Chemical
Definition of a basic life process?
Processes that distinguish, between a living and non living thing. Failure results in cell and tissue death - which may lead to organism death
What are the basic life processes?
Metabolism Responsiveness Movement Growth Differentiation Reproduction
What is mass?
Amount of matter in an object
What is weight?
Sum of mass and the gravitational attention of the earth
What is density?
Mass/volume (g/cm^3)
Describe an ionic bond?
Electrons completely transferred
Atoms become ions
Strong electrostatic force between ions
Describe a non polarised covalent bond?
Shared electrons
No ionic charge
Weaker than ionic bond
Describe a polarised covalent bond?
Unequal sharing of electrons due to a atom having a higher electronegativity, creating a delta positve and delta negative side
Describe what a synthesis reaction is?
Anabolic/endergonic (building up)
A + B = AB
Eg. amino acids to proteins
Involves condensation reactions
Describe what a decomposition reaction is?
Catabolic/exergonic
AB = A + B
E.g glycogen to glucose
Hydrolysis
Describe what an exchange reaction is?
Anabolic and catabolic
Endergonic and exergonic
AB + C = AC + B
Eg. glucose to ATP
Involves oxidation and reduction reaction at the same time
What’s a condensation reaction?
Removing water to form a bond
Anabolic process
What’s a hydrolysis reaction?
Adding water to break a bond
Catabolic process
Example of what oxidation and reduction reactions do in the body?
Break down macronutrients
Eg. Carbohydrate (glucose)
Fat (triglycerides)
Protein (amino acids)
Redox reaction equation?
e- donor + e- acceptor = A + B + ATP
E- donor (i.e reducing agent) is oxidised
e- acceptor (i.e. oxidising agent) is reduced
Cellular respiration redox reaction?
C6H12O6 + 6O2 = 6CO2 +6H20 + ATP
Glucose + Oxygen = CO2 + Water + energy
Glucose is oxidised
Oxygen is reduced
Oxidation and reduction reaction involving Pyruvate and Lactate?
Reduction:
Pyruvate + 2H = (via LDH) Lactate
Oxidation:
Lactate - 2H = (via LDH) Pyruvate
What do Dehydrogenases do?
Enzymes that Remove hydrogen
What do oxidases do?
Enzymes that Remove oxygen
Examples of co enzymes in redox reactions?
NAD+ (nicotinamide adenine dinculeotide)
FAD (flavin adenine dinucleotide)
What reaction does creatine kinase catalyse and when does it occur?
ATP + Cr = PCr + ADP + H(+)
Occurs everytime you contract a muscle
Definition of the mass action effect?
The effect of the concentration of chemicals in solution on the occurrence of a particular chemical reaction
What does increasing reactants in an equillibrium do?
Rate of forward reaction increases
What does increasing products in an equillibrium do?
Rate of reverse reaction increases
What is the first law of thermodynamics?
Energy cannot be created or destroyed, but simply changed from one form to another
Living and non living things
Definition of a fuel?
A compound for which some of it’s chemical energy can be transformed into other forms when a chemical reaction takes place
Features of glycogen?
Stored in liver and muscle
Stored with water ( 1g glycogen with 3g water)
Fuel brisk walking for 12 hours
Features of triacylglycerol?
Stored in adipose tissue
Occupies 80% of adipose tissue
Fuels brisk walking for 15 days
What is chemical energy?
Type of potential energy stored in bonds of compounds and molecules
Features of an exergonic reaction?
Releases energy
Downhill reaction
Energy is freed up
Features of an endergonic reaction?
Uphill
Store or absorb energy
Typically coupled to an exergonic reaction
What is the second law of thermodynamics?
All of the potential energy in a system degrades to the unusable form of kinetic or heat energy
Process of change reflects entropy
3 types of energy conversion?
Mechanical work
Chemical work
Transport work
How is energy measured in food?
Bomb calorimetry
Order of calories of Carbs, protein, lipids?
Smallest is carbs, then protein then lipids
Lipids contain most hydrogens
What is the coefficient of digestibility?
Ability of body’s digestive process to extract potential energy
Far higher % in meats than in legumes, as legumes have a lot of fibre
Enzyme definition?
A specfic protein catalyst that accelerates the forward and reverse rates of chemical reactions, without being consumed or changed in the reaction
Which enzyme breaks down Hydrogen peroxide down to water and Oxygen?
Catalase
Features of irreversible reactions?
Large energy change
Nonequillibrium reaction
Less common
Features of reversible reactions?
Small energy change
Equillibrium reaction
Product also a substrate for the reverse reaction
More common
Lock and key theory process?
Substrate matches active site of enzyme, forming an substrate enzyme complex
Enzyme-substrate complex splits into yield product
Enzyme now available for interaction with other substrate
What does the induced fit theory add?
That the enzyme changes shape to become complementary to the substrate
What is Michaelis constant (Km)?
Concentration of substrate required to produce 1/2 the vMax (maximal velocity)
3 factors that influence enzymes and why?
pH: if not optimal structure of enzyme is altered
Temperature
Enzyme concentration
What are co enzymes?
Organic substance
Assist with enzyme work
Facillitate enzyme binding with substrate
Temporary carrier
What are allosteric enzymes?
Produce S shaped graph as substrate concentration affects V max in a strange way
Think of Haemoglobin
Features of salts?
Ionic bonds
Structural components
Electrolyte properties
Features of acids and bases?
Covalent bonds
Involved in metabolic control and homeostasis
Features of salts and acids/bases?
Dissociate in water
Damaging in high concentrations
Features of acids (proton donors)?
Dissociate in water releasing hydrogen ions
What is a H+ ion?
Hydrogen atom which has lost an electron
3 examples of acids in the human body?
Hydrochloric acid in digestion
Carbonic acid in chemical buffering
Citric acid in the second stage of CHO breakdown
Features of bases (proton acceptors)?
Dissociate in water releasing OH- ions
What does Avogadro’s number represent?
The number of atoms in 12g of 12C, approximately 6.02 x 10^23
What does mM mean?
Millimoles per dm^3
So will be the same as moles just multiplied by 10^-3
Formula for pH?
pH = -log10 {H+}
What does logarithmic scale mean for pH?
a pH of 5 is 10x more acidic than one of pH6
and a pH of 4 is 100x more acidic than a pH of 6
Features of strong acids?
Dissociate completely
Irreversible
An example is HCl
Features of weak acids?
Dissoociate partially
Reach equilibrium
Therefore reversible and concentration driven
An example is Carbonic acid
Definition of a buffer?
Chemical and physiological mechanisms that moderate changes in {H+}
What does pH of smaller than 7.35 trigger in the blood?
Acidosis
What does pH of higher than 7.45 trigger in the blood?
Alkalosis
3 mechanisms that regulate pH in the blood?
Chemical buffering
Pulmonary ventilation
Renal function
Describe the intergrated buffering system in the blood?
The main chemical buffer is bicarbonate
H(+) + HCO3- = H2CO3 = CO2 + H2O
Hydrogen ion + bicarbonate = Carbonic acid = Carbon Dioxide and Water
So excess H+ will drive reaction to the right
And excess CO2 drives reaction to the left
As CO2 in constantly removed by the lungs, the system keeps working, provided there is sufficient HCO3-
H+ is excreted by the kidneys, regenerating the HCO3- in the process
Acidosis drives reaction to the right
Alkalosis drives the reaction to the left
What are the possible variations in the arterial?
PO2
PCO2
pH
and temperature
What provides the most important respiratory stimulus?
PCO2, small increases in inspired air trigger large increases in ventillation
pH of the plasma is also monitored as acidosis reflects CO2 retention and carbonic acid formation
Inspiratory activity increases to eliminate CO2 and reduce arterial levels of carbonic acid
Features of a chemical buffer?
Provides the first line of defence
Consists of a weak acid and the salt of that acid
When H+ concentration is elevated, the reaction produces the weak acid
In contrast, when H+ concentration is low the buffering reaction moves in the opposite direction and releases H+
Immediate response, catalysed by enzymes
Features of renal buffering?
Slow response
Renal tubules regulate acidity through chemical reactions that secrete ammonia and H+ into urine, and reabsorb alkali, chloride and bicarbonate
So restores bicarbonate into the blood
It’s the only pathway to eliminate acids other than the carbonic acid
So urine acidity reflects {H+}
Features of ventilatory buffering?
Fast response, important during exercise
Changes the CO2 concentration
Increase in H+ conc stimulates the ventilatory control, and therefore alveolar ventillation, and therefore CO2 removal
What can intense exercise cause?
Increase H+ concentration from CO2 production and lactate formation
Large temporary disturbances in acid-base balance
A low plasma pH can cause nausea, headache and dizziness
When does the stimulus to breath come from?
Increased arterial PCO2 and H+ conc
What does hyperventilating before breath holding do?
Causes alveolar PCO2 to decrease
Extends breath holding duration
Homeostasis definition?
The maintenance of internal conditions
Basic structure of the negative feedback loop?
Receptor (detects internal conditions) to Integrator (decides wha to do) to effector (makes required change) then back to receptor
Functions of cell membranes?
Primary function is a barrier, prevents entry of some substances, and retains others
Regulates transport of fuel into the cell
Provides surfaces for protein attachment
Communication between extra and intra-cellular environments
What are cell membranes made up of?
Membrane is a bi layer of phospholipids
Membrane spanning proteins (intrinsic)
Associated proteins (extrinsic)
It is semi permeable - allows some small uncharged molecules through, larger molecules require transport systems
Types of passive (no energy) transport?
Simple diffusion
Facillitated diffusion
Osmosis
Filtration
Types of active (requires energy) transport
Sodium-Potassium pumps
Bulk transport - Endocytosis, Exocytosis, Phagocytosis
Secondary active transport
Definition of simple diffusion?
The passive movement of molecules or particles from regions of higher concentrations to regions of lower
concentrations
Definition of facilitated diffusion?
Transport of substances across a biological membrane from an area of higher to lower concentration by means of a carrier molecule
So requires a transport membrane protein, which ports can open and shut. This may be stimulated by voltage, hormones, ADP/ATP ratios
What do leak channels do?
Let substances leak out/in, down a concentration gradient
Describe SOPI (sodium out, potassium in) pumps (very basic)?
Function - The Na+ and K+ pump restores the electro-chemical gradient following contraction
Resting potential membrane is -70mV
There are K+ and a Na+ leak channels
There are Na+ pumps which are pumping them outside the membrane (requires ATP) 3 of them per time
K+ pumps are pumping (requires ATP) them into the membrane (2 at the time)
Voltage gated channels open for Na+ open after a stimulus creates a -55mmV, it leaks in bringing potential up to +30mV, opening the K+ voltage gates, letting them leak out also the Na+ channels close
Describe insulin activated glucose transport?
Insulin binds to receptors, can move into cell down a concentration gradient
Describe the homeostatic process of maintaining blood glucose levels?
If it’s high:
Beta cells of pancreas stimulated to release insulin into the blood
Insulin causes body cells to take up more glucose
It also causes the liver to take up glucose and store it as glycogen
Blood glucose level declines to a set point, stimulus for insulin release diminishes
Low blood glucose levels:
Alpha cells of pancreas stimulated to release glucagon into the blood
Glucagon causes liver to break down glycogen and release glucose into the blood
Blood glucose rises to a certain point stimulus for glucagon release diminshes
What is osmosis?
The simple diffusion of water (solvent), across a partially permeable membrane from an area of high concentration to low
Examples of osmotic pressure?
Put a cell in isotonic solution, there is no net movement of water
Put cell in hypotonic water, water moves into cell and may cause it to burst (osmotic lysis)
Put cell in Hypertonic solution, water moves out of the cell, causing it’s cytoplasm to shrink (plasmolysis)
Osmolaity definition?
The concentration of a solution expressed as the total number of solute particles per kilogram
Osmolarity definition?
The concentration of a solution expressed as the total number of solute particles per litre
Features of hypotonic drink?
1-3% carb content
Quickly replaces fluids lost by sweating but low in carbs
Used by people who need hydration without the replace of carbs
Features of an isotonic drink
6-8% carb content
Quickly replace the fluids lost by sweating and provide a boost of carbohydrates
Features of Hypertonic drinks?
10%+ carb content
To supplement carbohydrate intake
Used by people who need a lot of energy, or to top up muscle glycogen stores after a workout
Why not just drink pure water to rehydrate?
Can lead to water intoxication - fatal disturbance in brain function when normal balance of electrolytes is pushed outside safe limits by excessive water intake
Definition of filtration?
Movement of water and solutes across the membrane due to hydrostatic pressure from the Cardio Vascular system
What is endocytosis?
Bulk transport into the cell (forms a vesivle from the plasma membrane)
What is exocytosis?
Bulk transport out of the cell (released via a secretory vesicle)
What is phagocytosis?
Ingestion of bacteria or other material by phagocytes
What is secondary active transport?
A form of active transport, across a biological membrane in which a transporter protein couples the movement of an ion (typically Na+ or H+) down it’s electrochemical gradient to the uphill movement of another molecule or ion against a concentration/electrochemical gradient
Describe insulin release from Pancreatic Beta cell?
Normally K+ ATP sensitive channel is open, and K+ can diffuse out of the cell
Voltage gated calcium channels are normally closed, doesn’t let calcium into the cell
High glucose in blood
Glucose enters the Beta cell via facilitated diffusion (GLUT 2 transporter)
Glucose is metabolised to Produce more ATP, so ratio between ATP and ADP increases and ATP sensitive potassium channel closes
Potassium can no longer leave cell
Causes depolarisation of membrane (becomes more positively charged)
Opening the Voltage gated calcium channels
Calcium flows in and stimulates the release of insulin via excytosis from storage granules
Describe the process that generates a muscle contraction?
Nerve impulse arrives at terminal of motor neuron. ACh leaves neuron via exocytosis, this happens by calcium voltage gates opening up, and Ca2+ triggers exocytosis of ACh
ACh diffuses across synaptic cleft and triggers an action potential (allows Sodium to enter synaptic cleft)
Muscle AP travels along transverse tubule opening Ca2+ channels in SR (sarcoplasmic reticulum) , allowing calcium ions into sarcoplasm
Ca2+ binds to troponin, exposing binding sites for myosin
Myosin heads bind to actin and initiate power stroke
Ca2+ release channels in SR close and Ca2+ active transport pumps use ATP to restore low level of Ca2+ in sarcoplasm
