IMMS - Biochemistry Flashcards
1
Q
What are the proportions of water distribution in the body?
Base this on a 70kg male
A
2
Q
How can water move between ICF and ECF?
A
-Water freely permeable through OCF and ECF through interstitium
-Determined by osmotic contents
-Any change causes water shift
-Always equal = isotonic
3
Q
What is in the ECF?
A
-Sodium main contributor to ECF osmolality and volume
-Anions:
-Chloride
-Bicarbonate
-Glucose + urea
-Protein = colloid osmotic pressure (oncotic)
4
Q
What is in the ICF?
A
Predominant cation id potassium
5
Q
What are interstitial fluid and plasma?
A
-Interstitial fluid - surrounds the cells but dows not circulate
-Plasma - circulates as the fluid component of blood
6
Q
What is osmalality?
A
Measures the concentration of all chemical particles found in the fluid or part of the blood
7
Q
What affects plasma osmolality and how is it estimated?
A
-Largely determined by sodium and associated anions
-Estimated plasma osmalality = 2[NA] + 2[K] + urea + glucose mmol/L
-Ions are multiplied by 2 as they have a greater efect
8
Q
What do changes in plasma osmolality do?
A
-Intra and extracellular osmolality are equal
-Change in plasma osmolality pulls or pushes water across cell membranes
9
Q
Label the gains and losses of water within a day:
A
10
Q
Label the diagram of the volumes of water gained or lost by each of these sources:
A
11
Q
What should be the daily net gain of water?
A
- 0
-Under normal circumstances fluid intake = fluid loss
12
Q
Why don’t we give water intravenously?
A
-Hypo-osmolar/hypotonic vs cell
-Water enters blood cells causing them to expand and burst - haemolysis
-Only occurs in vicinity of intravenous cannula
13
Q
Describe changes of ECF osmolality:
A
-Very tightly regulated
-Changes in ECF osmolality lead to rapid response
-Normal plasma osmolality 275-295mmol/kg
-Water deprivation or loss leads to chain of events
14
Q
What is the normal range of plasma osmolality?
A
275-295mmol/kg
15
Q
Label this diagram:
A
16
Q
What is the effect of ADH?
A
-Acts on distal convoluted tube
-Increases permeability of water
-More water moves from inside the tubule back into the medulla to be reabsorbed
-Lower volume of more concentrated urine
17
Q
Describe the reaction to an increase in ECF volume:
A
-Cause a slower response compared to osmolality
-RAAS
18
Q
Label the 5 effects of the RAAS:
A
19
Q
Label the basic mechanism of RAAS:
A
20
Q
What are the 5 main causes of water depletion?
A
-Reduced intake
-Sweating
-Vomiting
-Diarrhoea
-Diuresis/ diuretics
21
Q
Name some common symptoms of dehydration:
A
-Thirst
-Dry mouth
-inelastic skin
-Sunken eyes
-Raised hamatocrit
-Weight loss
-Confusion - brain cells particularly vulnerable
-Hypotension
22
Q
Label this diagram:
A
23
Q
What are the risks of over-hydration?
A
-Hyponatraemia
-Cerebral overhydration:
-Headache
-Confusion
-Convulsions
24
Q
What is hydrostatic pressure?
A
-Pressure difference between plasma and interstitial fluid
-Water moves from plasma into interstitial fluid
25
What is oncotic pressure?
-Pressure caused by the difference in protein concentration between the plasma and interstitial fluid
-Water moves from interstitial fluid into plasma
-Also called osmotic pressure
26
Label this diagram:
What does it show?
Normal water movement between the interstitium and plasma
27
Label this diagram:
What does it show
Normal movement of water between interstitium and plasma
28
What is oedema?
Excess accumulation of fluid in interstitial space
29
What can cause oedema?
-Disruption of the filtration and osmotic forces of circulating fluids:
-Obstruction of venous blood or lymphatic return
-Inflammation; increased capillary permeability
-Loss of plasma protein
30
What is serous effusion?
Excess water in a body cavity
31
What does this show?
Pitting oedema
32
Describe the pathogenesis and 4 things that can cause it:
33
What does this show?
Describe it:
-Inflammatory oedema
-Higher capillary permeability
-More water moving out into interstitial space than returning
34
What does this show?
-Describe it:
-Venous oedema
-Increased capillary hydrostatic pressure meaning increase water pushed out
35
What does this show?
Describe it:
-Lymphatic oedema
-Blockage of fluid movement into the lymphatic system
36
What does this show?
-Hypoalbuminaemic oedema
-Loss of osmotic gradient for movement of water back into vessels
37
Describe how pleural effusions occur:
-Normal pleural space has around 10mL fluid
-Balance between:
-Hydrostatic and oncotic forces in visceral and parietal pleural vessels
-Lymphatic drainage
-Pleural effusions result from disruption of this balance
-Different fluids can enter pleural cavity
38
What is transudate?
-Fluid pushed through capillary due to high pressure within capillary
-Low protein content
-In contect of pleural effusions
39
What is exudate?
-Fluid that leaks around cells of the capillaries
-Caused by inflammation and increased permeability of pleural capillaries to proteins
-High protein content
-In context of pleural effusions
40
What is measured to differentiate an exudative from a transudative pleural effusion?
What can each mean?
-Pleural fluid protein
-Exudative:
-Mailgnancy
-Pneumonia
-Transudative:
-LVF
-Cirrhosis
-Hypoalbuminaemia
-Peritoneal dialysis
41
What is the difference in protein levels between exudates and transudates?
-Exudates have a high protein level compared to transudates
-May also contain cells, bacteria and enzymes
42
What are the general principles of measuring plasma sodium?
-Normal range 135-145 mmol/L
-Concentration is a ratio, not total body content measurement
-High or low [Na] usually due to gain or loss of water rather than Na
43
What clinical effects usually show with plasma disorders?
-Clinical effects are on brain
-Due to constrained volume (skull)
-Rate of change more important than absolute levels
44
What two groups of things can cause hypernatremia and some examples?
-Water deficit:
-Poor intake
-Osmotic diuresis
-Diabetes insipidus
-Sodium excess:
-Mineralocorticoid (aldosterone) excess
-Salt poisoning
45
What 4 groups of things can cause hyponatremia and examples?
-Artefactual
-Sodium loss:
-Diuretics
-Addison's disease
-Excess water:
-IV fluids (iatrogenic)
-SIADH
-Excess water ++ and sodium +:
-Oedema
46
What can hypernatremia cause?
-Cerebral intracellular dehydration (tremors)
-Irritability
-Confusion
47
What defined a living organism?
-One or more cell
-Capable of reproduction
-Responding to the environment
-Adapting and changing (inheritance)
-Require source of energy
-Growth and development
48
What is an organelle?
Aggregates of macromolecules used to carry out a specific function in the cell
49
Label this diagram:
50
What functions do macromolecules have?
-Osmotic
-Structural
-Optical
-Enzymatic
-Other complex functions
51
What are some examples of macromolecules?
-Haemoglobin
-DNA
-Glycogen
-Rhodopsin
-Collagen
52
Give 5 features of water:
-Universal solvent
-Polarity
-Hydrogen bonding
-Liquid over range 0-100o
-Max density at 4oC
53
What doesn't water interact with?
-Non-polar substances
-Lipids
-Aromatic compounds
53
What doesn't water interact with?
-Non-polar substances
-Lipids
-Aromatic compounds
-Hydrophobic compounds
54
What was probably the first step of life?
-First functional and structural definition of life
-Encapsulation of 'self' in a membrane of some kind (vesicle)
55
What are 4 groups of carbohydrates?
-Monosaccharides
-Disaccharides
-oligosaccharides
-Polysaccharides
56
Label the groups:
57
What groups are present on monosaccharides?
-Chain of carbons, hydroxyl groups, one carbonyl group
-An aldose has an aldehyde
-A ketose has a ketone
58
How do you name monosaccharides base on their carbons?
-Triose = 3C
-Tetrose = 4C
-Pentose = 5C
-Hexose = 6C
59
What do monosaccharides generally exist as and why?
-Ring structures
-Reaction of the aldehyde or ketone groups with a hydroxyl group of the same molecule
60
What are 4 sugar derivatives?
-Aminosugars - containing an amino group (often acetylated)
-Alcohol-sugars
-Phosphorylated - containing phosphate groups
-Sulphated - sulphate groups
61
What are glycosidic bonds and where are they found?
-Hydroxyl group of one monosaccharide react with OH or NH (to form glycosides)
-O glycosidic bonds form saccharides
-N glycosidic bonds found in nucleotides and DNA
62
What are oligosaccharides?
-Contain 3-12 monosaccharides
-Products of digestion of polysaccharides, or part of complex protein/lipids
63
What are polysaccharides?
Formed by thousands of monosaccharides joined by glycosidic bonds
64
What are proteoglycans?
Long unbranched polysaccharides radiating from a core protein
65
What are fatty acids?
-Straight C chains
-Mostly 16-20
-Methyl group and a carboxyl group at the ends
-Melting point decreases with degree of saturation
66
What are phosphoacylglycerols?
-Derive from phosphatidic acids
-Formed from fatty acids esterified to glycerol and phosphorylated at C3
67
What are sphingolipids?
Derive from ceramide (serine, palmitic acid and another fatty acid)
68
What are steroids derived from and what are their properties?
-Cholesterol
-Fat soluble
-Diffuse through cell membranes
69
What are eicosanoids?
-Synthesised from 20C atoms
-Eicosanoic acids with 3,4,5 double bonds
-Major biological functions
70
What are the components of nucleotides?
-Nitrogenous base
-Sugar
-Phosphate
71
What bonds form within a nucleotide?
-Ester bond between phosphate and sugar
-N-glycosidic between sugar and base
72
Describe amino acids:
-20 different
-Carbon with:
-Amino group
-Carboxyl group
-Side chain (R)
-charge determined by all 3
-Charge changes with pH of environment
-Side chain often determines polarity or nonpolarity
73
What id dissociation of amino groups?
-At different pH, carboxyl and amino groups are ionised (charged)
-Some aminoacids also have ionisable side side
74
Examples of non-polar amino acids:
All hydrophobic
75
Example of polar amino acids:
Usually contain sulphur
76
Example of charge amino acids:
77
What can some amino acids contain:
-Benzene ring
-Aromatic amino acids
78
What is folding in protein chains determined by?
-Charged interactions
-Flexibility
-Physical dimensions
79
What are 4 examples of protein structure-function relationships?
-Immunoglobulins
-Fibrous proteins - collagen
-Enzymes
-Channel and carrier proteins, receptors and neurotransmitters
80
What do amino acids form?
Linear chains - polypeptides
81
What are the properties of peptide bonds?
-Very stable
-Partial C-N bond
-Flexibility around C atoms not involved in bond - allows multiple conformations
-Usually one preferred native conformation determines mainly by type of side chain and their sequence in the polypeptide
82
What cleaves peptide bonds?
Proteolytic enzymes
83
What is a protein?
-Large polypeptide
-usually from a few 10s to 1000s amino acids
-Huge variety of functions arises from different number of 3D shapes
-Function is dependant on structure
84
What do these represent?
-Backbone - line following peptide bonds
-Cartoon - representation showing the fundamental secondary structures
85
Label the different protein structures:
86
What forces hold proteins together?
-Van der Waals forces
-Hydrogen bonds
-Hydrophobic forces
-Ionic bonds
-Disulphide bonds
87
What are hydrophobic forces?
-Uncharged and non-polar side chains poorly soluble in water
-Repelled
-Form tightly packed cores in interior of proteins excluding water molecules
88
What do disulphide bonds usually form between?
-Covalent bond between side chains of cysteine residues
-Extracellular domains of proteins
-Extra stability is needed in extreme conditions
89
Describe the primary structure of proteins:
-Linear sequence of amino acids linked by peptide bonds
-Functionally and evolutionary related proteins could have similarity
-Determines 3D conformation
90
Describe secondary structure of proteins:
-H bonds between each carbonyl group and H attached to N 4 amino acids along chain
-Side chains look outwards
-Proline breaks helix
91
What is this?
Describe it:
-Formed by H bonds between linear regions of polypeptide chains
-From two or same protein, parallel or unparallel
92
Describe the tertiary structure of a protein:
-Overall 3D conformation
-Forces:
-Electrostatic
-Hydrophobicity
-H-bonds
-Covalent bonds
-Conformations change with:
-pH
-Temperature
93
Describe quaternary structure of proteins:
-3D structure of protein composed of multiple subunites
-Same non-covalent interactions as tertiary structures
94
How do we determine protein structure?
-X-ray diffraction of protein crystals
-X-rays reflect off electrons within the protein
95
What is the function of enzymes?
-Powerful biological catalysts
-Bind substrates and convert them into products
-Release products to return to their original form
-Provide a way to regulate rate of reactions
96
What can enzymes be a marker for?
-Disease markers
-increased levels due to certain diseases
97
What can enzymes be a target for?
Can be drug targets for disease
98
What are these?
99
What is this?
-Porphyrin ring
-Core of each haem group
-Holds an iron atom
100
What is an iron-containing porphyrin called?
-Heme
-Iron atom is site of oxygen binding
101
Where does haemoglobin name come from?
Concatenation of heme and globin
102
What is carbonic acid effect on Hb and what reaction ocurrs?
.
103
What is effect on O2 binding to protonated Hb?
104
What does this show?
105
How does temperature affect haemoglobin oxygen dissociation?
106
How does carbon dioxide in the blood affect haemoglobin oxygen dissociation?
107
What factors affect haemoglobin saturation and why?
-Temperature
-H+
-PCO2
-Modify structure of haemoglobin and alter its affinity for oxygen
108
What do an increase and decrease of temperature, H+ and PCO2 cause on haemoglobin?
-Increase:
-Decrease haemoglobins affinity for oxygen
-Enhance oxygen's unloading from blood
-Decrease acts in opposite manner
-All these parameters are high in peripheral capillaries where oxygen unloading is target
109
What is sickle cell anaemia?
-Genetic disorder
-Formation of hard, sticky, sickle-cell shaped red blood cells
-Contrasts to biconcave-shaped red blood cells
-Caused by mutation in haemoglobin
110
Where is malaria most prevalent?
111
What are immunoglobulins?
-Antibodies
-Produced to bind to antigens, typically toxins or proteins on the surface of microbial agents
-Targets labelled for destruction by cells in the immune system or by lysis through complement system
112
What is the structure of immunoglobulins?
-Supporting scaffold that serves to display highly variable loops of complementarity determining regions (CDRs)
-Diverse nature of CDR regions enables range of reversible bonding effects to act between antibody and antigens
113
Where are the antigen binding domains on immunoglobins?
-Top of supporting structural frameworks
-"arms" of antibody molecule can hinge to allow a degree of movement
114
What is the essence of antibody/antigen interaction?
What is the part of the antigen involved in this interaction called?
-Very close proximity of antibody CDR regions and antigen surface
-Innate contact allows combination of relatively weak interactions to produce strong binding surface
-CDR loops have sequence of amino acids that "complement" antigen surface
-This portion of antigen bound is known as epitope
115
What is the epitope?
Portion of the antigen recognised by the CDR loops
116
What are proteins a patchwork of?
-Charge - +ve or -ve -COO- -NH2+
-Hydrophobicity
-Polarity
-Bulk
117
What does this show?
Describe them:
-Vand der Waals forces
-Weak and short range
-Instantaneous dipole
-Only effective in short distances
118
What does this show?
Describe them:
-Hydrogen bonds
-Sharing of a proton between electronegative groups
119
What does this show?
Charged amino acids can be acidic or basic
120
What does this show?
Bulky amino acid groups can project from the amino acid surface
121
What does this show?
-Hydrophicity
-Hydrophobic groups resist exposure to surrounding aqueous solvent (H2O
122
What does this show?
123
Describe prokaryotic DNA:
-No nuclear membrane
-Single chromosome often
-Circular
124
Describe DNA in eukaryotes:
-Nucleus
-Bound to proteins to form chromatin
-Different appearance at different functional moment
-Mitosis - chromatin condenses into visible chromosomes
-Each made of 2 identical strands (chromatids) joined in centre at centromere
-Some DNA in mitochondria
125
What are the functions of DNA?
-Template and regulator for transcription and protein synthesis
-Genetic material, structural basis of hereditary and genetic diseases
126
What is the structure of nucleic acids?
127
How do the two strands of DNA run in relation to each other?
Antiparallel
128
What do DNA sequences act as and when is this useful?
-Templates
-DNA replication
129
What is the shape of DNA?
-Double helix
-Major and minor grooves within the backbone
-Allow proteins to enter for replication
130
Describe prokaryotic chromosomes:
-Supercoiled
-Circular
-2.5 x 106 kDa
-4 x 106 bases
-2mm linear
131
Describe human chromosomes:
-Complex packaging
-22 x2 + X, Y or X,X
-4 x 109 kDa
-3 x 109 bp
-2m linear (all)
132
What is heterochromatin and euchromatin?
-Heterochromatin:
-Tightly packed
-Inactive
-Euchromatin:
-Loosely packed
-Actively transcribed
133
What is a solenoid?
Compacted nucleosomes
134
Label this:
What does it show?
The cell cycle
135
Why is cell cycle control and DNA repair so important in medicine?
-Cancer
-Oncogenes
-Proto-oncogenes
-Cell cycle control
-DNA repair
136
Describe DNA replication:
-Prior to cell division DNA opens at **replication fork**
-Base sequence on each parent strand is copied into a **complementary** daughter strand
-Two parental strand separate in front of fork
-New DNA made behind fork, composed of a new and old strand: replication is semi-conservative
-Many proteins are involved in DNA replication, binding proteins and enzymes
137
How fast is DNA replication and how long?
-700-1000bp per second
-6 billion base pairs
138
What does O show?
-Origins of replication
-Multiple points of origin
139
What enzymes are involved in human DNA replication?
-Polymerases (5' to 3')
-Helicase
-Ligase
-Nuclease
-Primase
-Topoisomerase
140
In what direction is DNA replicated by DNA polymerase?
-Reads 3' to 5'
-**Prints** 5' to 3'
-Substrates are deoxyribonucleotides triphosphates
-Enzyme stays on the strand, at the same time extends and proof-reads
141
What opens the DNA strands during DNA replication?
-DNA helicase enzyme
-Single stranded binding proteins (SSB) keep it open
-**Topoisomerase** unwinds the supercoiling
142
Label this diagram:
What does it show?
DNA replication complex
143
What other function does DNA polymerase have?
-Editing function
-Detects incorrect insertion of base and will excise repeat
144
What can be used to amplify regions of DNA?
Polymerase Chain Reaction (PCR)
145
What are sources of constant genome damage?
-Chemical
-Radiation
-Spontaneous insertion of incorrect bases during replication
146
What is benzopyrene?
-Product of incomplete combustion of hydrocarbonds
-Barbecued food is good source
-DNA - adduct: Reacts with bases to form a bulky group that disrupts replication
147
Describe the effect of ionising radiation on DNA:
-Can damage bases
-Causes breaks in phosphate backbone
-UV forms thymine dimers
148
When can mutations occur?
-DNA damage:
-Chemicals
-UV
-Radiation
-Chance
-DNA repair:
-Base or nucleotide excision
-Mismatch repair
149
What do we have an elaborate system for?
-Detecting DNA damage
-Initiating repair
-Many are keyed in or linked to cell cycle control
-p53 as an example - tumour suppressor gene (sits on DNA and detects damage)
150
What can p53 do?
151
What does bp stand for?
Base pairs
152
What does kDa stand for?
-KiloDaltons
-1000 atomic mass units
-One dalton is mass of H atom
153
What does S stand for?
-Svedberg unit
-Refers to mass and shape of cellular organelles
-High S means larger mass
-Not additive
-Used in ultracentrifugation - how particles are separated
154
What are 3 differences between human DNA and RNA?
-DNA is double-stranded with a complementary chain / RNA is single-stranded and any double stranding is usually with itself
-Three types of RNA: mRNA, rRNA, tRNA with different functions
-DNA is present in cells at all time, many mRNA species only accumulate following cell stimulation and are short lived
155
Describe mRNA:
-Messenger RNA
-Printed as long linear transcript
-Processed to the mature form (in proximity of nuclear membrane)
-Has 5'CAP and 3' Poly A tail
156
Describe rRNA:
-Ribosomal RNA
-Ribosomes are abundant in eukaryotic cytoplasm
-Four main types of rRNA combine with proteins to form 80S ribosomes
157
What is the interaction between the 3 types of RNA?
rRNA prints mRNA with help from tRNA
158
Describe tRNA:
-Transfer RNA
-Carry amino acids to ribosomes and check that they are incorporated in the right position
-Each tRNA only carries one amino acid so at least 20 different types
-Very small molecules
-Anticodon triplet sequence pairs with mRNA to ensure right amino acid for right triplet
159
Label:
160
What region sits before the target gene to be transcribed?
Promotor region
161
What are 3 features of the genetic code?
-Degenerate, but unambiguous
-Many amino acids specified by more than one codon
-Each codon specifies only one amino acid
-Almost universal
-All organisms use same code
-Fewer than 10 exceptions
-Non-overlapping and without punctuation
-Codons not overlap
-Each nucleotide only read once
162
What causes this?
-Lactate blocks repressor
-Complementary to active site deactivating it
163
What initiates gene expression?
-Proteins called "transcription factors" find their way to specific sequences 5' of 1st exon
-This is called promotor region
-"transcription complex" forms around TATA box 5' of 1st codon
-Helix opens, DNA separates
-RNA pol II starts mRNA creation
164
What is an enhancer?
Stretch of DNA far from gene which affects DNA expression
165
What do these show?
166
What 6 things can turn off gene expression?
-Activation of repressors (inhibit RNA polymerase binding)
-Each step of RNA transcription or processing finds no longer actively produced transcription and processing proteins
-Complexes do not form anymore - lack of phosphorylation
-Enzymes no longer activated
-DNA stability
-Other unknown mechanisms
167
Label this diagram:
168
Describe membrane permeability (3):
-Maintains internal environment
-Selectively permeable
-For membrane transport, impermeable substances may need: Transport proteins, energy
169
Describe channel proteins and their functions
-Narrow aqueous pore
-Selective to: Size, charge
-Passive
-May be gated (voltage or ligand)
-Usually ions (e.g. Na+) or water (aquaporins)
170
Describe carrier proteins and their function:
-Specific binding site
-Undergoes conformational change
-Different types
-Active (pumps) or passive
171
What are the 3 different types of carrier proteins?
-Uniport - single substance
-Symport - two substances in the same direction
-Antiport - two substances in the opposite direction
172
What are the 3 main driving forces of substances into/out of cells?
-Chemical
-Electrical
-Electrochemical
173
What is the movement of substances based on?
-Presence of a gradient
-Either move with the gradient or can move against the gradient
174
Describe the chemical driving force:
-Based on concentration differences across the membrane
-All substances have a concentration gradient
-Force directly proportional to concentration gradient
175
Describe the electrical driving force:
-Also known as membrane potential
-Based on distribution of charges across the membrane
-Only charge substances
-Force depends on size of membrane potential and charge of ion
176
Describe the electrochemical driving force:
-Combines chemical and electrical forces
-Net direction is equal to sum of chemical and electrical forces
-Only charged substances
177
What are the two main types of membrane transport and 2 sub-types of each?
-Passive:
-Simple diffusion
-Facilitated diffusion
-Active:
-Primary
-Secondary
178
Describe passive transport:
-Does not require an input of energy
-Substances move down its gradient
-Two type:
-Simple
-Facilitated
179
What is an example of passive transport?
-Glucose
-GLUT4 carrier protein
-Skeletal muscle and adipose tissue
-Glucose uptake by facilitated diffusion
-Expression upregulated by insulin
180
Describe too much glucose in pregnancy:
-Principal fetal nutrient - fetal gluconeogenic enzymes inactive + low arterial PO2
-From maternal circulation
-Fetal glucose level directly proportional to mother
-No mechanism to limit uptake
-Excess glucose can cause significant fetal harm
181
Describe a condition that affects glucose uptake:
-GLUT1 deficiency syndrome
-Very rare
-Mutation in gene
-Reduces available glucose to brain cells
-Symptoms - seizures, microcephaly, developmental delay
182
Describe active transport:
-Requires input of energy
-Substances move against its concentration gradient
-Primary and secondary
183
Describe primary active transport:
-Directly uses a source of energy, commonly ATP
-Common example - Na+/K+ ATPase
184
What's an example of primary active transport going wrong?
-ATP7B protein is a Cu2+ ATPase in liver that transports copper into bile
-Wilsons disease - mutations in ATP7B gene
-Dispersion of copper in liver and other tissues - eyes, brain
-Symptoms - liver disease, tremor, Kayser-Fleischer rings
185
Describe secondary active transport:
-Transport of a substance against its gradient COUPLED to transport of an ion (usually Na+ or H+) which moves it down its gradient
-Uses energy from generation of ions electrochemical gradient (usually primary AT)
-Na+/glucose cotransporter proteins (SGLT)
-Intestinal lumen
-Transports glucose from low to high
-Na+/K+ ATPase generates sodium gradient for co-transport
186
Describe an example of when secondary active transport goes wrong:
-SGLT1 transports glucose and galactose from intestinal lumen
-Glucose-galactose malabsorption
-Very rare
-Mutation is SGLT1
-Inability to transport glucose and galactose resulting in malabsorption
-Symptoms - severe, chronic diarrhoea, dehydration, failure to thrive
187
How does communication between cells take place?
-Signalling molecules
-E.g. hormones, neurotransmitters and growth factors
188
What do signalling molecules bind to?
-Receptors
-Intracellular - steroid hormones
-Cell-surface - peptide hormones
-Second messengers - amplification
-Affect gene expression in the nucleus either directly or through signalling cascades
189
Describe a disease that affects cell signalling:
-Cholera
-G-proteins integral part of G-protein-couples receptors on cell membrane surfaces
-Vibrio cholerae bacteria produce cholera toxin
-Crosses cell surface membrane
-Modifies subunit (intracellular action)
-Increased cAMP
-Stimulates transporters to surface membrane of intestinal cells
-Massive secretion of ions and water into gut
-Severe diarrhoea and dehydration
190
Describe endocytosis:
-Large molecules require different methods of transport
-Transport into a cell by encapsulating it into a vesicle
191
Describe exocytosis:
-Large molecules require a different method of transport
-Golgi vesicle fuses with membrane to release substance
192
Describe cystic fibrosis in terms of transport:
-Mutation in CFTR protein
-Chloride channel
-Found in many tissues - gut, pancreas, lungs and skin
-"secretory epithelium"
-Abnormal function results in sticky, viscous mucus
-no osmotic drag
193
What are some drugs that target membrane transporters?
-Cardiac glycosides
-Proton pump inhibitors
-Loop diuretics
-Thiazide diuretics
194
What is metabolism and metabolic processes?
-Metabolism - sum of the chemical reactions that take place within each cell of a living organims
-Sequence of chemical reactions: particular molecule is converted into some other molecule or molecules in a defined fashion
195
What 4 main pathways are dietary components metabolised?
-Biosynthetic
-Fuel storage
-Oxidative processes
-Waste disposal
196
What does anabolic and catabolic mean?
-Anabolic - synthesise larger molecules from smaller components
-Catabolic - break down larger into smaller
197
Are the 4 main metabolism pathways of dietary components anabolic or catabolic?
-Biosynthetic - anabolic
-Fuel storage - anabolic
-Oxidative - catabolic
-Waste disposal - either
198
What type of reaction provides energy for cell processes from fuel molecules?
Catabolism
199
What can catabolism provide energy for?
Anabolism
200
What is the Kreb's cycle and example of?
Catabolism
201
What can Krebs cycle produce?
Some substrates for biosynthesis
202
What do reactions often require?
Co-factor
203
How is energy conserved in oxidative phosphorylation?
Via transfer of electrons in the inner mitochondrial membrane
204
What does the electron transport chain consist of?
4 complexes and associated compounds like ubiquinone
205
What does the electron transport chain do?
-Oxidises NADH and FADH2
-Thus releasing energy which is used to produce ATP
206
What gradient drives ATP production?
Electrochemical proton gradient
207
What tissue is this?
Describe it:
-Adipose
-85% fat
-Storage of energy-rich molecules
208
What tissue is this?
Describe it:
-Liver
-Metabolically active
209
What type of tissue is this and what is its function?
-Muscle
-Activity
210
Label this diagram:
What does it show?
The Cori cycle
211
What kind of molecule is insulin?
-Anabolic
-Aids the build up of molecules within cells
212
What does this show?
The effects of insulin
213
What does insulin do in adipocytes?
-Stimulates uptake of VLDL and glucose
-Stimulates conversion of fatty acids to triacyglycerols
214
What does insulin do in skeletal muscles?
-Stimulates uptake of amino acids to be converted to protein
-Stimulates absorption of glucose
215
What does insulin do in liver cells?
-Stimulates uptake of amino acids to be converted to protein
-Stops conversion of amino acids to glucose
-Stimulates conversion of glucose to glycogen
-Stimulates conversion of glucose to fatty acids and release of VLDL
216
What are 7 dietary components?
-Fuels
-Essential amino acids
-Essential fatty acids
-Vitamins
-Minerals
-Water
-Xenobiotics
217
How many main dietary energy sources are there and what are they?
-3
-Carbohydrates (recommended primary energy source)
-Lipids
-Proteins
218
What is normal BMI?
-18.5 - 25: Normal/healthy
-25-30: Overweight
->30: Morbidly obese
-Measured in Kg/m2
219
What do we do with dietary energy sources?
Oxidation
220
What types of carbohydrates do we use?
Monosaccharides and disaccharides
221
What are proteins made of?
-Amino acids in chains
-Carbon
-Oxygen
-Hydrogen
-Nitrogen (16% by weight)
222
What lipids do we use?
-Triglycerides
-3 fatty acids esterified to one glycerol moeity
-More reduced than other energy sources
223
How are dietary fuels stored in the body?
-Fat - Adipose tissue - 15% water
-Carbohydrate - glycogen in liver and muscles
-Protein - muscle - 80% water
224
What happens to excess energy intake?
-Store as triglycerides in adipose (15kg)
-Store as glycogen (200g in liver, 150g in muscle, 80g in liver after overnight fast)
-Store as protein in muscle (6kg)
225
Why is storage of glycogen limited compared to triglycerides?
-Hydrophilic whereas triglycerides are hydrophobic
-Attracts water
226
How much energy per gram of carbohydrate?
4kcal/g
227
How much energy per gram of protein?
4kcal/g
228
How much energy per gram of alcohol?
7kcal/g
229
How much energy per gram of lipid?
9kcal/g
230
How much energy per gram of 4 molecules?
231
What is the primary source of ATP supplied to the body at rest during low intensity activities?
-Oxidative system (aerobic)
-Primarily uses carbohydrates and fats
232
Label the 4 things that energy can be utilized for:
233
What is BMR?
-Basal Metabolic Rate (BMR)
-Energy needed to stay alive at rest
-Measure of the energy required to maintain non-exercise bodily fuctions
234
What are 5 examples of non-exercise bodily functions?
-Respiration
-Contraction of heart muscle
-Biosynthetic processes
-Repairing and regenerating tissues
-Ion gradients across cell membranes
235
What conditions are essential for measuring BMR (6)?
-Post absorptive (12 hour fast)
-Lying still at physical and mental rest
-Thermo-neutral environment (27-29)
-No tea/coffee/nicotine/alcohol in previous 12 hours
-No heavy physical activity previous day
-Establish steady state (30 min)
236
What 5 factors can decrease BMR?
-Age
-Gender
-Dieting/starvation
-Hypothyroidism
-Decreases muscle mass
237
Why do people with a higher muscle to fat ratio have higher BMR?
-Muscle cells require more energy to maintain than fat cells
-As we get older we tend to gain fat and lose muscle so BMR tends to decrease with age
238
What factors increase BMR?
-Body weight (BMR)
-Hyperthyroidism
-Low ambient temp
-Fever-infection-chronic disease
239
What is the rough estimate for BMR?
1kcal/kg body mass/hour
240
What does NHS nutrition guidelines recommend as the daily energy intake for patients who are not severely ill or injured, nor at risk of re-feeding syndrome?
25-35 kcal/kg/day
241
What happens metabolically during an overnight fast?
-Decrease in insulin
-Glycogenolysis
242
How much glycogen does the liver have after an overnight fast and why?
-Brain requires about 150g of glucose a day
-After an overnight fast, the liver only has about 80g of glycogen
243
What may happen during a longer period of fasting/starvation?
-Glucose must be formed from non-carbohydrate sources (amino acids, fatty acids)
-Gluconeogenesis
244
What happens during 2-4 days of starvation?
Decreased insulin and increased cortisol = lipolysis and proteolysis
-Gluconeogenesis
245
What does gluconeogenesis use?
-Lactate
-Amino acids:
-Muscle
-Intestine
-Skin
-Glycerol:
-Fat breakdown
246
What happens during >4 days starvation?
-Liver -> ketones from fatty acids
-Brain adapts to using ketones
-Decreased BMR = accomodation
247
What is malnutrition?
A state of nutrition with a deficiency, excess or imbalance of energy, protein or other nutrients, causing measurable adverse effects
248
What are adverse effects of malnutrition?
Adverse effects are on:
-Tissue/body form (shape/ size/ composition)
-Body function
-Clinical outcome
249
What are the dangers of re-feeding too quickly?
-**Re-feeding syndrome**
-Re-distribution of phosphate, potassium, magnesium etc. due to insulin
-Switch back to carbohydrates as the main fuel which requires phosphate and thiamine
250
What are essential nutrients?
-Body can't synthesise them
-Essential amino acids
-Essential fatty acids
-Vitamins
-Minerals
251
What are micronutrients?
What are their uses in the body?
-Trace elements and vitamins
-Co-factors in metabolism
-Gene expression
-Structural components
-Antioxidants
252
What are 3 uses of vitamin C (ascorbic acid)?
-Collagen synthesis
-Improve iron absorption
-Antioxidant
253
Give 3 facts about vitamin C:
-Ascorbic acid
-Sourced from fruit and vegetables
-Heat labile
254
What are 5 functions of vitamin B12?
-Protein synthesis
-DNA synthesis
-Regenerate folate
-Fatty acid synthesis
-Energy production
AND THEREFORE CELL DIVISION
255
What is a function of vitamin B1?
-Thiamine
-Helps with energy production
256
What is a function of vitamin B2?
-Riboflavin
-Energy production
-Helps body use other B vitamins
257
What is a function of vitamin B3?
-Niacin
-Helps body use protein, fat and carbohydrate to make energy
-Helps enzymes work properly
258
What is a function of biotin?
-Allows body to use protein, fat and carbohydrate
259
What is a function of vitamin B6?
-Pyridoxin
-Helps body make and use protein and glycogen which is stored energy in muscle and liver
-Helps form haemoglobin
260
what are some functions of folate (folic acid)?
-Helps produce and maintain DNA and cells
-Helps make red blood cells and prevent anaemia
-Getting enough folic acid lowers risk of having baby with birth defects like spina bifida
261
What is the prudent diet (main 5)?
-5+ servings of fruit/veg
-Base meals around starchy carbohydrate foods
-No more than 5% energy should come from free sugars
-0.8g/kg/day protein
-No more than 30g for men and 20g for women of saturated fat
262
What are the last 4 parts of prudent diet?
-Adults should have no more than 2.4g of sodium per day (6g salt)
-Advised to not regularly drink more than 14 units of alcohol a week (over >3 days)
-Avoid excess dietary supplementation
-Adequate calcium
263
Label this diagram:
264
Label this diagram:
265
What can vesicles do?
266
What does this show?
Phospholipid bilayer
267
What makes up phospholipids and describe the components:
268
Label the diagram:
What does it show?
269
What modifies the fluidity of the phospholipid bilayer?
-Cholesterol
-Temperature
270
What is the cell membrane freely permeable to?
-Water (aquaporins)
-Gases (CO2, N2, O2)
-Small uncharged polar molecules (urea, ethanol)
271
What is the cell membrane impermeable to?
-Ions (Na+, K+, Cl-, Ca2+)
-Charged polar molecules (ATP, glucose-6-phosphate)
-Large uncharged polar molecules (glucose)
272
What are the 6 ways substances can cross the cell membrane?
-Simple diffusion
-Facilitated diffusion
-Primary active transport
-Secondary active transport
-Ion channels
-Pino/phago-cytosis
273
What do each of these show an example of?
274
Why are membranes and membrane proteins needed?
-Cell polarisation
-Compartmentalisation
-Ionic gradients (diffusion, membrane potential)
-Tightly regulated
-Disease disrupts this
275
What is the membrane potential (Em,/sub>)?
-Potential difference across the cell membrane generated by differential ion concentrations of key ions (K+, Na+, Ca2+, Cl-)
-Stable in most cells
276
What is the major determinant of Em?
K+
277
What does convention dictate with membrane potential?
-Extracellular fluid potential = 0 mV (reference)
-Membrane potential is that on intra-cellular membrane
278
Describe the various individual diffusion potentials that make up membrane potential:
+ve ion - -ve value if diffusing from IC to EC (K+)
+ve ion - +ve value if diffusing from EC to IC (Na+ or Ca2+)
-ve ion - -ve value if diffusing from EC to IC (Cl-)
279
What equation relates to diffusion potential?
Recite it:
-Nernst equation
280
What is a key determinant of Em and what is it dependant on?
-Ion conductance (permeability)
-Channel numbers
-Channel gating
-Change ion permeability -> change Em
281
What plays a major role in K+ homeostasis and what can affect it?
-Kidneys and aldosterone
-Renal failure
-Conn's syndrome (too much aldosterone)
282
Describe increased concentration of K+:
-Hyperkalaemia
-Em less -ve (tending to depolarisation)
-Reaches threshold more easily
-Cell depolarisation more likely
-Heart - decreased SAN firing / bradycardia
283
Describe decreased concentration of K+:
-Hypokalaemia
-Em more -ve (tending to hyperpolarisation)
-Disrupts various K+ channels
-Abnormal heart rhythms (arrhythmias)
284
Describe ischaemia in terms of Em:
-Hypoxia = low ATP
-Opens KATP channel
-Em less -ve (~-55mV)
-Depolarises more easily
-Fast Na+ inhibited (~-55mV)
285
What happens in terms of Ca2+ during ischaemia?
-Slow calcium mediated depolarisation:
-Early repolarisation
-Decreased plateau
-Decreased action potential time
286
Describe:
287
Describe 3 features of epithelia:
-Require polarisation of plasma membrane
-Permits cell-specific function (secretion/absorption)
-Strongly adhere to neighbours (tight junctions)
288
What are ways in which cells communicate?
-Cell membrane receptors:
-Signal transduction
-Internalise extra-cellular signal
289
What various receptors are involved in signal transduction?
-Ion channels
-Membrane-bound steroid receptors
-Neurotransmission
-Growth factors
-Nuclear steroid receptors
290
Describe the six parts of GPCR:
-Receptor - give primary specificity
-Three G-proteins (alpha, beta, gamma) (gamma gives further specificity)
-Enzyme to modulate second messenger (e.g. cAMP)
-Enzyme to terminate signal
291
What part of the G-protein determines second messenger?
Alpha G subunit
292
How does pH affect membrane function?
-Both extremes damage protein
-Inhibits cell function
293
What plays a critical role in acid:base homeostasis?
-Plasma Ca2+
-Cell membrane excitability/permeability
294
What about calcium is measured clinically?
-Total serum calcium
-Ionised (Ca2+)
-Unionised (Ca)
295
Describe serum calcium:
-45% free ionised Ca2+
-Biologically active
-Change Ca2+ (active) : Ca (inactive) with no change in total calcium
296
Describe alkalosis and acidosis in terms of calcium:
-Acidosis - less Ca2+ bound to plasma proteins (H+ ions buffered by albumin)
-Alkalosis - more Ca2+ bound to plasma proteins (fewer H+ ions on protein)
297
What are alkalotic patients more susceptible to?
-Hypocalcaemic tetany
-Due to increased neuronal Na+ permeability
298
Describe the 55% of calcium that is not bound in serum:
-Not biologically active
-45% bound to albumin
-10% anions - phosphate; lactate active form
299
Describe how temperature affects membrane function:
-Too cold - proteins slow down, membrane less fluid
-Too hot - proteins denature; increased membrane fluidity
300
Describe the conditions associated with body temperatures:
-Heat exhaustion core temp >37 but <=40
-Heat stroke core temp >=40
-Dehydration
301
What happens when core body temp decreases?
-Everything slows down
-Lowest survivable core temp 13.7
302
What can affect regulation of SAN action potential (temp)?
-Hypothermia
-Decreased depolarisation rate of cardiac pacemaker cells
-Bradycardia
-Abnormal heart rhythms
-Fibrillation
303
Describe hypokalaemia and the lethal triad:
304
What is the currency of metabolic energy?
Whats its composition
-Adenosine-5-triphosphate
-High energy molecules composed of adenine (purine base), ribose and 3 phosphate groups
305
What reaction of ATP is energetically favourable?
-Hydrolysis of ATP to ADP
-Releases inorganic phosphate, H+ and heat energy
306
Label this diagram:
What does it show?
ATP-ADP cycle
307
How do cells generate energy from nutrients?
-Glucose metabolism in a series of linked pathways:
-Glycolysis
-Krebs cycle
-Oxidative phosphorylation
308
Describe the 3 stages of glucose metabolism:
-Glycolysis - anaerobic breakdown of glucose to pyruvate, small amount of ATP production from substrate level phosphorylation
-Krebs cycle - oxidation of AcetylCoA to CO, generates coenzymes NADH and FADH2
-Oxidative phosphorylation - transduction of energy derived from fuel oxidation to high energy phosphate, generates large amount of ATP
309
Label this diagram:
310
Where does glycolysis occur?
Cytosol under anaerobic conditions
311
Why is glycolysis carried out?
-Emergency energy production pathway when oxygen limited (RBC, skeletal muscle)
-Generates precursor for biosynthesis
-G-6-P for nucleotides/glycogen
-Pyruvate for fatty acid synthesis
-Glycerol-3-P is backbone of triglycerides
312
What is an overview of glycolysis?
-1 glucose converted into 2 pyruvate, 2 NADH + H+ + 2ATP
-Preparative phase
-ATP generating phase
313
Describe the two phases of glycolysis:
314
Label the preparatory phase of glycolysis:
315
In what two stages of the preparatory phase of glycolysis is ATP used?
316
Label this diagram of the ATP generating phase of glycolysis:
317
In what 2 stages of the ATP generating phase of glycolysis is ATP generated?
318
Label this diagram of glycolysis
319
In what stages of glycolysis are ATP, NADH generated and used?
320
What 3 things regulate gylcolysis?
-Hexokinase
-Pyruvate kinase
-Phosphofructose kinase - 1 (PFK-1) (MAIN ONE)
321
What is the main regulator of glycolysis?
PFK-1
322
What are the two types of regulation of glycolysis?
-Allosteric
-Binds to non-catalytic site
-Conformational change
-Increase or decrease affinity for substrate
-Hormonal
-Increase or decrease gene expression of enzyme
-Indirect route - regulatory molecules
-Increase or decrease enzyme activity
323
What are activators and inhibitors of PFK-1?
-Activators:
-AMP
-Inhibitors:
-ATP
-Citrate
-F2, 6 BP
324
Why is AMP a PFK-1 activator?
-ADP derivative
-When ATP is used up, ADP accumulates and converted to AMP by adenylate kinase reaction to generate ATP
-Increasing AMP relieves inhibition of PFK-1 by ATP
325
What is the most important allosteric activator of PFK-1?
-Fructose-2,6-bisphosphate
-Mediates effect of insulin and glucagon
326
What product of Krebs cycle can allosterically inhibit PFK-1?
-Citrate
-Increase signals that cycle doesn't need more fuel
327
What happens to pyruvate in anaerobic conditions?
-Lactate formation catalysed by **lactate dehydrogenase**
-Regeneration of NAD+
328
What happens to pyruvate in aerobic conditions?
-Enters mitochondria and converted to Acetyl CoA and CO2 by **pyruvate dehydrogenase**
-Acetyl CoA can enter TCA cycle for more energy production
329
What is the equation for what happens to glucose in anaerobic conditions?
.
330
Label the diagram for what happens to pyruvate under anaerobic conditions:
.
331
What is the equation for what happens to pyruvate under aerobic conditions?
332
Describe the irreversible reaction of pyruvate under aerobic conditions:
-Catalysed by **pyruvate dehydrogenase** (multienzyme complex within mitochondrial matrix)
-Inhibited by high concentration of acetyl CoA and NADH
-inactivated by phosphorylation
-Activated by phosphate removal
333
Where does Krebs cycle happen?
Mitochondrial matrix under aerobic conditions
334
Why does the Krebs cycle occur?
-Generates LOTS of ATP
-Provides final common pathway for oxidation of carbohydrates, fat and protein via ACoA
-Produces intermediates for other metabolic pathways
335
What is an overview of Krebs cycle and its products?
-Acetyl CoA condenses oxaloacetate with acetate
-Oxaloacetate regenerated in Krebs cycle
336
Label the basic steps of Krebs cycle:
337
Label the products of Krebs cycle:
338
Label the enzymes of Krebs cycle:
339
What is the net energy gain for Krebs cycle?
340
What main enzymes regulate the Krebs cycle?
341
What regulates citrate synthase?
Stimulates:
-ADP
Inhbits:
-ATP
-NADH
-citrate
342
What regulates isocitrate dehydrogenase?
Stimulates:
-ADP
Inhibits:
-ATP
-NADH
343
What regulates alpha-ketoglutarate dehydrogenase?
Stimulates:
-Ca2+
Inhibits:
-ATP
-NADH
-Succinyl CoA
-GTP
344
What regulates pyruvate dehydrogenase?
Stimulates:
-Pyruvate
-ADP
Inhibits:
-ATP
-NADH
-Acetyl CoA
345
Where does oxidative phosphorylation occur?
Inner mitochondrial membranes during aerobic conditions
346
Why does oxidative phosphorylation occur?
-Releases majority of energy during cellular respiration
-Reduced NADH or FADH2 from glycolysis and krebs oxidised, electrons passed to ETC
-Energy released trapped in ATP
347
Describe oxidative phosphorylation:
-ETC accept electrons (reduced) and pass them on (oxidised)
-Electrons transferred to final electron acceptor (oxygen)
-Free energy used to power movement of H+ across inner membrane creating proton motive gradient
-ATP produced as protons flux in through **ATP synthase**
348
Describe oxidative phosphorylation:
-ETC accept electrons (reduced) and pass them on (oxidised)
-Electrons transferred to final electron acceptor (oxygen)
-Free energy used to power movement of H+ across inner membrane creating proton motive gradient
-ATP produced as protons flux in through **ATP synthase**
349
Label this diagram of oxidative phosphorylation:
350
What is the basic equation of oxidative phosphorylation?
351
What sources of stored energy are in the body and for how long will they last?
-Glycogen - 12 hours
-Fats - 12 weeks
-Protein - used when muscle glycogen stores fall
352
What makes up fatty acids?
-Carboxylic head
-Aliphatic tails
-Saturated and unsaturated
353
Where are most fatty acids derived from?
-Triglycerides
-Phospholipids
354
Describe fatty acid activation implications:
-Must be activated in cytoplasm before they can be oxidised in mitochondria
-If the Acyl-CoA has <12 carbons - it can diffuse through mitochondrial membrane
-Most dietary fatty acids have >14 carbons - taken through mitochondrial membrane using **carnitine shuttle**
355
Describe fatty acid activation:
356
Label this diagram of fatty acid b-oxidation:
Oxidation occurs at the beta carbon
357
Under normal conditions, how is acetyl-CoA used?
-Most utilised via the TCA acid cycle to produce glucose
-Small proportion converted to ketones
358
What are ketones?
three examples?
-Molecules produced by the liver from acetyl-CoA
-Characteristic fruity/nail polish remover smell
359
What are three examples of ketones?
360
What is produced during high rates of fatty acid oxidation?
-Large amounts of acetyl-CoA
-Exceeds the capacity of the TCA cycle which results in **ketogenesis**
361
What can acetoacetate be converted into?
-Can undergo spontaneous decarboxylation to acetone
-Enzymatically converted to beta-hydroxybutyrate
362
How are ketone bodies utilised?
-Utilised by extrahepatic tissues
-Conversion of beta-hydroxybutyrate and acetoacetate to **acetoacetyl-CoA**
-Requires enzyme **acetoacetate:succinyl-CoA transferase** which is found in all tissues but hepatic tissues
363
What things regulate ketogenesis?
-Release of free fatty acids from adipose tissue
-High concentration of glycerol-3-phosphate in liver results in triglyceride production, low level results in ketone body formation
-When ATP demand is high, acetyl-coA is likely to be further oxidised via TCA to carbon dioxide
-Fat oxidation is dependant upon amount of glucagon (activation) or insulin (inhibition)
364
Ketone production + usage during normal and low physiological conditions?
-Normal physiological conditions production of ketones occurs at low rate
-Carbohydrate shortages cause liver to increase ketone body production from acetyl-CoA
-Heart and skeletal muscles preferentially utilise ketone bodies for energy preserving glucose for brain
365
What is ketoacidosis?
-Occurs in insulin-dependant diabetics when dose is inadequate or because of increased insulin requirement (infection, trauma, acute illness)
-Often presented by newly diagnosed type 1 diabetics
-Chronic alcohol abuse
-Present hyperventilation and vomiting
366
Describe the flow chart of diabetic ketoacidosis:
367
Describe the flow chart of alcoholic ketoacidosis:
368
What are the consequences of ketoacidosis?
-Ketones relatively strong acids (pKa ~ 3.5)
-Excessive ketones lower blood pH
-Impairs ability of haemoglobin to bind to oxygen
369
What are the blood values for ketoacidosis?
370
What is the definition of homeostasis?
Maintenance of a constant internal environment
371
What are 5 examples of homeostasis in the body?
-Temperature
-Glucose
-Potassium
-Blood oxygen
-Hydrogen ion
372
What is the homeostasis model?
373
What are the 2 communication systems in the body?
-Hormones
-Electrical
374
What are the 3 categories of communication in the body?
-Autocrine
-Paracrine
-Endocrine
375
What is autocrine communication?
Cells communicating to themselves
376
What is paracrine communication?
-Cells communicating to neighbouring cells a short distance away
-Signal diffuses across gap between cells
-Inactivated locally so doesn't enter blood stream
377
What are 2 examples of paracrine communication?
-Interleukins:
-Immune system
-Mainly white blood cells
-PDGF
-Released from platelets
-Regulates cell growth
378
What is endocrine communication?
-Cells communicating to other cells elsewhere in the body
-Hormones in the blood
379
What are the main endocrine organs/glands?
-Hypothalamus
-Pituitary
-Thyroid
-Adrenals
-Pancreas
-Ovaries
-Testes
380
What is a hormone and how are the classified?
-Molecule that acts as a chemical messenger
-Amino-acid derivatives
-Peptide
-Steroid
381
What are amino acid hormones?
name and example:
-Derived from tyrosine
-Adrenaline
382
What are peptide hormones?
-Made of amino acids
-Vary in size from few amino acids to small proteins
-Some have carbohydrate side chains (glycoproteins)
-Hydrophilic (like water)
383
What types of hormone create a quick reaction in the body?
-Amino acid derivatives
-Peptide
384
Describe the action of TSH:
What kind of hormone is it?
Peptide
385
Describe steroid hormones:
-All made from cholesterol
-Different enzymes modify molecule to produce a variety of hormones
-Can't dissolve in water (hydrophobic)
-Can dissolve in lipids
386
What kind of reactions produce a slow response?
-Steroid
-Example: testosterone
387
Explain the role of testosterone:
388
What is a positive feedback loop?
Signal is amplified
389
What is a negative feedback loop?
-Slowing down/regulating process
-Maintains homeostasis
