Learning outcomes Flashcards
1
Q
Define aetiology
A
Cause of disease
2
Q
Define pathogenesis
A
How a disease develops
3
Q
Define signs
A
What the doctor sees
4
Q
Define symptoms
A
What the patient feels
5
Q
Define diagnosis
A
Determining the nature and cause of disease
6
Q
Define prognosis
A
A prediction of the probable outcome of the disease
7
Q
What are the classifications of disease?
A
Growth Unnatural Degenerative Developmental Inflammation Circulatory
8
Q
What proportion of the body’s water is in the ECF and ICF?
A
ECF= 1/3 ICF= 2/3
9
Q
What proportion of ECF is ISF and plasma?
A
ISF= 80% Plasma= 20%
10
Q
What is negative feedback control?
A
A change is detected by receptors, which is then fed to an integration level and compared to a reference level. A difference causes a signal to be sent to an effector and the change is negated
11
Q
What is feed forward control?
A
Changes can be anticipated and negated before they occur
12
Q
What is the first law of thermodynamics?
A
Energy can be converted from one form to another but not created or destroyed
13
Q
What is the second law of thermodynamics?
A
All energy transformations ultimately lead to more entropy in the universe
14
Q
How do cells maintain order if the laws of thermodynamic state they should not?
A
Even though the processes create more ordered, the heat that is released into the environment creates more entropy overall
15
Q
Why is equilibrium not reached in biological reaction pathways?
A
Products from one reaction are used in the next reaction in the pathway
16
Q
What is dynamic steady state?
A
The concentrations are constant but equilibrium is not reached
17
Q
Define metabolism
A
The chemical processes in a living organism that allow food to be used for tissue growth
18
Q
Define catabolism
A
Releases energy, negative G, spontaneous
19
Q
Define anabolism
A
Require energy, positive G, not spontaneous
20
Q
What are the uses of ATP and ADP in metabolic processes?
A
Act as free energy carriers, coupling anabolic and catabolic reactions using phosphate group transfers
21
Q
What are the functions of NADP/NAD and FAD in metabolic processes?
A
Used in reduce reactions as electron carriers
22
Q
What are the major elements used to construct human biomolecules
A
O H C N Na Cl K Ca S P
23
Q
What is the importance of functional groups?
A
Affect how a molecule acts around others
24
Q
What is molecular configuration?
A
The fixed arrangement of atoms in a molecule
25
What is molecular conformation?
The precise arrangement of atoms in molecule
26
What are the 5 types of chemical reactions in the body?
```
Redox
Making/breaking C-C bonds
Internal rearrangements
Group transfers
Condensation/hydrolysis
```
27
Give an example of a redox reaction in the body
Glycolysis in muscles
28
Give an example of making/breaking C-C bonds in the body
Cleavage of glucose in glycolysis
29
Give an example of internal rearrangement reactions in the body
Glucose-6-phosphate--> fructose-6-phosphate in glycolysis
30
Give an example of a group transfer reaction in the body
Transfer of phosphate group in glycolysis
31
Give an example of a condensation/hydrolysis reaction in the body
Formation and breaking of nucleic acids and proteins
32
Describe the structures present in all cells
Nucleus
| Cytoplasm
33
What are the roles of the nucleus in eukaryotic cells?
Contains DNA, nucleoprotein and some RNA
34
What is the function of the nucleoli?
Sites for ribosomal synthesis and assembly
35
What is the endoplasmic reticulum?
Interconnecting network of membranous tubules, vesicles and cisternae
36
What are the two forms of the endoplasmic reticulum?
Rough ER
| Smooth ER
37
What is the function of the rough endoplasmic reticulum?
Synthesises and packages proteins
38
What is the function of the smooth endoplasmic reticulum?
Lipid biosynthesis and membrane synthesis and repair
39
What is the function of ribosomes?
Protein factories
40
What is the golgi apparatus and its function?
Stack of flattened vesicles that package and process secretory proteins and synthesise complex polysaccharides
41
What are lysosomes and their function?
Membrane bound organelles containing granular materials used to break down bacteria and debris
42
What are peroxisomes and what is their function?
Membrane bound organelles containing catalase to regulate hydrogen peroxide concentration and oxidases involved in beta-oxidation of fatty acids
43
What is the structure of mitochondria?
Permeable outer membrane containing porin
Folded inner membrane- cristae
Filled with amorphous matrix
44
What is the function of the mitochondria?
Powerhouse of the cell
45
What are the components of the cytoskeleton?
Microfilaments- fine strands of actin
| Microtubules- Larger than microtubules
46
What is the role of the cytoskeleton?
Provide strength and support
| Allow for cell motility
47
What is a hydrogen bond?
Electrostatic attraction between polar groups when H is bound to O, N or F
48
What defines a molecule's water solubility?
Polarity
49
Define the term amphipathic
A molecule containing both hydrophobic and hydrophilic parts
50
Give an example of an amphipathic molecule
Phospholipids- hydrophilic heads, hydrophobic tails
51
How do amphipathic molecules act in water?
Minimise disruption by forming bilayers or micelles
52
How can pH be calculated?
pH=-log[H=]
| pH=pKa=log[A-]/[HA]
53
What are buffers?
Solutions of weak acids and their salt
54
How do buffer solutions work?
If OH- is added, it combines with free H+ to form H2O
If H+ is added, it combines with OH- to form H2O
These ions are then replaced by the dissociation of acid and water and the pH remains constant
55
Describe the basic structure of a cell membrane
Phospholipid bilayer containing proteins
56
List the classes of membrane proteins
Integral membrane proteins
| Peripheral proteins
57
What are integral membrane proteins?
Amphipathic proteins that cannot be removed without disrupting the membrane
58
What are the types of integral membrane protein and their functions?
Channels, through which ions can cross
Carriers, to transport substances across membranes
Enzymes, with binding sites
Receptors, recognition sites
59
What are peripheral proteins?
Non-amphipathic proteins that can be removed without major disruption to the membrane
60
What function do peripheral proteins have?
Usually enzymatic
| Important for cell shape and motility
61
What is the protein content of different cell membranes?
Schwann cells= 18%
Normal= 50%
Mitochondria= 75%
62
What factors aid diffusion?
Large surface area
High permeability
High concentration gradient
63
What must molecules be to diffuse through the membrane?
Small
Uncharged
Hydrophobic
64
What are the different types of channel proteins?
Open channels
| Gated channels- ligand or voltage gated
65
How do voltage gated channels work?
Changes in the electrical potential act on charged regions of channel proteins, changing their conformation, opening or closing the channel
66
How do ligand gated channel proteins work?
When a certain chemical binds to a channel protein, it produces a change in conformation, and opens or closes the channel
67
What is the electrochemical gradient?
The difference in charge between two compartments
68
What charge is carried by the inside of the cell?
-70mV
69
What are carrier mediated transport systems?
Proteins with binding sites for a substance, that changes conformation upon binding, allowing the molecule to diffuse into the cell, and allowing the protein to return to its original shape
70
What are the types of carrier mediated transport systems?
Facilitated diffusion
| Active transport
71
What is active transport?
Transport against a concentration gradient, requiring energy from ATP
72
Define osmolarity
Concentration of a solution, expressed as the total number of osmoles per litre
73
Define tonicity
Concentration of non penetrating solutes on the two sides of the membrane
74
What are the 3 types of solutions that can occur in the body?
Isotonic
Hypotonic
Hypertonic
75
What are isotonic solutions?
Equal number of non-penetrating cells on either side of the membrane
76
What are hypotonic solutions?
Solutions where the concentration of non-penetrating particles are higher inside the cell than outside
77
What are hypertonic solutions?
Solutions where the concentration of non-penetrating cells is higher outside the cell than inside
78
Explain the movement of water in and out of the cell in hyper and hypotonic solutions
```
Hypotonic= water moves into cell
Hypertonic= water moves out of cell
```
79
Describe the process of endocytosis
Invagination of the membrane to form a vesicle around the target substance, which eventually separates from the membrane on the cytoplasmic side and migrates into the cell
80
Describe the process of exocytosis
Invagination of the membrane around the target substance from the cytoplasmic side, which opens out into the extracellular space
81
What is epithelial tissue?
Tissue that covers surfaces and separates compartments
82
What are cell-cell junctions?
Junctions created between epithelial cells providing cell anchorage, sealing intracellular spaces and allowing for cell-cell communication
83
What are desmosomes?
Adhering junctions proving firm anchorage
84
What are tight junctions and what is their function?
Joining of membrane between two cells, forming a virtually impermeable barrier, sealing sections
85
What are gap junctions and what are their functions?
Connection between cytoplasm of two cells, allowing for cell-cell communication
86
What are cell-extracellular matrix junctions called?
Hemidesmosomes
87
What is the function of hemidesmosomes?
Anchor cells
88
What are the types of epithelial cells?
Squamous
Cuboidal
Columnar
89
What is the structure and function of simple squamous cells?
Thin, single cell, allows for easy diffusion
90
What is the function of simple cuboidal cells?
Secrete, absorption, pumping
91
What si the function of ciliated columnar cells?
Move mucus
92
What is the structure of stratified squamous epithelial cells?
Multiple layers, thick, layers can be sloughed off to allow for new growth
93
What is the function of stratified cuboidal cells?
Protection
94
What is the function of stratified columnar cells?
Protection and secretion
95
What epithelial cells are in the liver?
Hepatocytes
96
What functions do hepatocytes have?
Secretion
| Line blood vessels and bile ducts
97
How are cells arranged in the kidneys?
Arranged into nephrons
98
What are the functions of the kidney nephrons?
Filtration of blood, partial absorption of filtrate
99
What do epithelial cells line in the kidney?
Blood vessels and the renal pelvis
100
What are glands?
Collections of multi or single celleular secretory epithelial cells
101
What are the 2 types of glands and where do they secrete into?
Endocrine- secrete into bloodstream
| Exocrine- secrete onto surface i.e. sweat
102
What are the different gland structures?
Simple- tubular, acinar
| Compound- tubuloacinar
103
What kind of secretions does each gland type secrete?
```
Tubular= thin, watery
Acinar= thicker, mucousal
```
104
What are the consequences of abnormal glandular function?
```
Overproduction= pituitary giantism
Underproduction= pituitary dwarfism
```
105
What is the extracellular matrix comprised of?
Fibres
Ground substance
Tissue fluid
106
What kind of fibres are present in the extracellular matrix?
Collagen fibres
107
What are the differences between collagen and elastic fibres?
Collagen is flexible bit inelastic
| Elastic fibres are very elastic
108
What is group substance composed of?
Proteoglycans
Glycoproteins
Hyaluronic acid
Water
109
What are the three layers of the skin?
Epidermis
Dermis
Hypodermis
110
What are the 5 layers of the epidermis?
```
Stratum basale
Stratum spinosum
Stratum gramulosum
Stratum lucidium
Stratum corneum
```
111
How does the stratum basale bind?
To the basement membrane via hemidesmosomes
| To other cells via desmosomes
112
How is the stream granulosum defines?
Presence of keratohyalin granules
113
What is the turnover rate of the strum corneum?
30 days
114
What 2 layers is the dermis composed of?
Papillary layer
| Reticular layer
115
What is the papillary layer of the dermis composed of?
Loose connective tissue
Blood vessels
Nerve endings
116
What is the reticular layer of the dermis composed of?
Sense irregular connective tissue
Collagen bundles
Elastic fibres
117
What is the interface between the dermis and epidermis like?
Irregular
118
What are the functions of bone?
Mechanical support and attachment for muscles, tendons, ligaments and joints
Protects internal organs
Mineral reservoir
Support blood formation
119
Describe the process of endochondral ossification
Bone forms as cartilage first
Blood vessels and osteogenic cells invade the cartilage framework
Cartilage remains as growth plates until 18-21 years old
120
Describe the process of intramembranous ossification
Bone forms as a fibrous plate
| Bone cells differentiate from fibroblasts and haematopoietic precursors
121
What is the composition of bone?
20% water
35% proteins- collagen type 1, growth factor proteins, other matrix proteins
Minerals
122
What are the 3 areas of long bone and where are they found?
Epiphyses- end of a bone
Metaphyses- between the two
Diaphyses- shaft of bone
123
What is the epiphyses of long bone made up of and why?
Trabecular (spongey) bone
| Act as a softer interface at joints
124
What is the diaphyses of bone composed of?
Cortical bone
125
What is cortical bone of the diaphyses in long bone arranged into and why?
Haversian canals
| Gives bone strength
126
What are osteoclasts?
Bone reabsorbing cells
127
What are osteoblasts?
Cells that lay down more bone
128
What are osteocytes?
Sensors of mechanical pressure and damage
129
What are the 4 classes of amino acids?
Acidic
Basic
Polar
Nonpolar
130
What are the functions of proteins in the body?
```
Movement
Protection
Transport
Enzymes
Receptors
Structural
Storage
Hormones
Control of gene expression
```
131
What is the primary structure of proteins?
Sequence of amino acids linked by peptide bonds
| Beads on a string structure
132
What is the secondary structure of proteins?
A level of protein folding involving hydrogen bonds between amino acid residues that are close together into either alpha helices or beta pleated sheet
133
What bonds hold together the alpha helix?
H bonds between N-H and the C=O groups
134
What is the tertiary structure of proteins?
A level of protein folding involving amino acid residues that are far apart in the linear sequence
135
What bonds can form in the tertiary structure of proteins?
```
Van der Waals
Ionic interactions
Hydrogen bonds
Sysulphide bridges
Hydrophobic interactions
```
136
What is the quaternary structure of proteins?
Joining of protein and prosthetic subunits
137
What is an enzyme cofactor?
A non protein component needed for activity
138
What is a prosthetic group of an enzyme?
Covalently bonded cofactor
139
What is an apoenzyme?
The protein component of an enzyme containing a prosthetic group
140
How do enzymes catalyse reactions?
Increase rates of spontaneous reactions
Lower activation energy
Accelerate movement towards equilibrium
141
What is the Michaelis constant and how is it calculated?
Km- the concentration of the substrate that catalyses the associated reaction at half of the maximum rate
Vmax (max rate of reaction) / 2
142
What does a high Km mean?
Low enzyme affinity
143
What does a low Km mean?
High enzyme affinity, faster reaction
144
How do competitive inhibitors work?
Non-covalently bind to enzymes in the same way the intended substrate does
145
How do non-competitive inhibitors work?
Non-covalently bind to a site other than the active site and change the shape of the active site
146
Explain the concerted model of allosteric enzymes
Each subunit can flip between conformations with a high and a low Km
When one substrate binds, it increases the affinity of all other subunits for the substrate
147
Explain the sequential model of allosteric enzymes
Binding causes a change in one subunit, causing a change in another to make further binding easier
148
What are the major carbohydrates in the diet?
Monosaccharides- glucose, galactose, fructose
| Disaccharises- maltose, sucrose, lactose
149
What is the difference between Glucokinase and hexokinase?
```
Glucokinase= high Vmax, which Km
Hexokinase= low Vmax, low Km
```
150
Where is glucokinase found and how does it work?
Liver
High Vmax and Km mean it only picks up glucose when the concentration is high, but it does so quickly, meaning as much glucose is trapped in the liver as possible
151
Where is hexokinase found and how does it work?
Tissues
| Can bind to glucose even at low concentrations and means tissues are easily satisfied
152
What is glycogen?
A polymer of glucose with (alpha 1-->4) linked subunits and an (alpha1-->6) branch every 8-12 residues
153
How is glycogen synthesised?
Glucogenin covalently binds glucose from UDP-glucose to form chains of approx 8 subunits
Glycogen synthase then takes over and extends the chains until they are broken by glycogen branching enzyme to form the branching points
154
How is glycogen degraded?
Glucose subunits are removed from the ends of the branches one at a time as G-1-P
155
What are the 2 phases of glycolysis?
Preparatory
| Payoff
156
What are the 10 steps of glycolysis?
1. Phosphorylation of glucose
2. Conversion of G-6-P to F-6-P
3. Phosphorylation of F-6-P to F-1,6-bisP
4. Cleavage of F-1,6-bisP
5. Interconversion of triose sugars
6. Oxidation of G-3-P to 1,3-bisPG
7. P transfer from 1,3-bisPG to ADP
8. Conversion of 3-PG to 2-PG
9. Dehydration of 2-PG to PEP
10. Transfer of P from PEP to ADP
157
What catalyst is involved in phosphorylation of glucose, what is needed for the reaction to take place and is the ΔG positive or negative?
Hexokinase
1 ATP
Negative ΔG
158
What catalyst is involved in the conversion of G6P to F6P and is the ΔG positive or negative?
Phosphohexose isomerase
| Positive, but very low, ΔG
159
What catalyst is involved in phosphorylation of F6P to F1,6bisP, what is needed for the reaction to take place and is the ΔG positive or negative?
Phosphofructokinase
1ATP
Negative ΔG
160
What catalyst is involved in the cleavage of F1,6bisP and is the ΔG positive or negative?
F1,6bisP aldolase
| Positive ΔG
161
What catalyst is involved in the interconversion of triode sugars and is the ΔG positive or negative?
Triose phosphate isomerase
| Positive ΔG
162
What catalyst is involved in the oxidation of G3P to 1,3bisPG, is the ΔG positive or negative and what is produced?
Glyceraldehyde 3-phosphate dehydrogenase
Positive ΔG
2 NADH produced
163
What catalyst is involved in the P transfer from 1,3bisP to ADP, is the ΔG positive or negative and what is produced?
Phosphoglycerate kinase
Negative ΔG
2 ATP produced
164
What catalyst is involved in the conversion of 3PG to 2PG and is the ΔG positive or negative?
Phosphoglycerate mutase
| Positive, but very low, ΔG
165
What catalyst is involved in the dehydration of 2PG to PEP and is the ΔG positive or negative?
Enolase
| Positive ΔG
166
What catalyst is involved in the transfer of P from PEP to ADP, is the ΔG positive or negative and what is produced?
Pyruvate kinase
Very negative ΔG
2 ATP and pyruvate produced
167
What is gained per molecule of glucose invested in glycolysis?
2ATP and 2 pyruvate
168
What is the function of gluconeogenesis?
Convert pyruvate back into glucose
169
What reactions are catalysed by lactate dehydrogenase?
Interconversion of lactate and pyruvate
170
What reactions are catalysed by pyruvate dehydrogenase?
Interconversion of pyruvate and acetyl coA
171
What is the fate of blood lactate?
Lactate is transported to the lover in the blood and converted back to glucose using gluconeogenesis
172
What is the cori cycle?
The cycle between glycolysis and gluconeogenesis
173
How many bypass reactions are in gluconeogenesis and how many are reverse reactions?
4 bypass reactions
| 7 reverse reactions
174
What is the fate of absorbed galactose?
Joins glycolysis through conversion to G1P by UDP. This is then converted to G6P to enter glycolysis
175
What is the fate of absorbed fructose?
Forms F1P through phosphorylation, then glyceraldehyde, then G3P to join glycolysis
176
What is the pentose phosphate pathway?
Cycle producing NADPH and pentose sugars needed for nucleic acid synthesis
177
What are the phases of the posts phosphate pathway?
Oxidative, irreversible
| Non-oxidative, reversible
178
What happens in the oxidative, irreversible part of the pentose phosphate pathway?
G6P is converted to a pentose phosphate
| NADPH generated
179
What happens in the non-oxidative, reversible part of the pentose phosphate pathway?
G6P is interconverted with various 3,4,5,6 and 7 carbon sugars
180
What is an x-ray?
Electromagnetic packet of energy with wavelength between 0.1 and 10 nanometres
181
Briefly describe how an X-ray works?
High energy electrons are fired at a heavy atom material
The collision of the electrons and heavy materials creates braking radiation in the form of x-rays
The x-rays are then directed at the target and some rays are absorbed and some pass through and hit the imaging film, creating the image
182
What has the least to the most absorption of x-rays?
Air
Fat
Muscle
Bone
183
How do ultrasounds work and what are they used to image?
Firing sonic waves with frequencies between 2 and 18 megaHertz into the patient
Soft tissues and embryonic development
184
How does a CT scan work and what is it most commonly used for?
Taking a series of 2D x-rays around an axis of rotation to create a 3D image
Head
185
What is fluoroscopy?
Imaging technique used to obtain real time moving images of the internal structures of the body
186
What is iodinated contrast media?
IV radiocontrast containing iodine which enhances the visibility of vascular structures and organs during radiographic procedures
187
What is barium used for in x-rays?
Absorbs x-ray photons, helping to outline the GI tract
188
Where does the citric acid cycle occur?
Mitochondril matrix
189
What do pyruvate and fatty acids form to enter the civic acid cycle?
Acetyl coA
190
What is produced from every turn of the citric acid cycle?
3 NADH
2 CO2
1 FADH2
1 GTP
191
What is the final stage of respiration and where does it take place?
Electron transport chain
| Mitochondrial matrix and intramembranous space
192
What proteins are involved in the electron transport chain?
NADH-Q oxidoreductase
Succinate Q reductase
Q cytochrome C oxireductase
Cytochrome C oxidase
193
What is the function of NADH Q oxidoreductase in the electron transport chain?
Reduce NADH and pass electrons to uboquinone
| Pump H+ ions into intramembranous space
194
What is the function of succinate Q reductase in the electron transport chain?
Reduces FADH2 and passes electron to ubiquinone
195
What is the function of Q cytochrome C oxidoreductase in the electron transport chain?
Passes electrons from ubiquinol to cytochrome C
| Pumps H+ ions into intramembranous space
196
What is the function of cytochrome C oxidase?
Pass electrons from cytochrome C to oxygen
| Pump H+ ions into intramembranous space
197
What is the function of pumping H+ ions across the inner mitochondrial membrane?
Create a proton gradient so the protons can diffuse back through into the matrix, turning ATP synthase
198
Describe the process by which H+ ions pass through the inner mitochondrial membrane
As the protons passively diffuse the membrane, ATP synthase turns, yielding energy to bind ADP and Pi
199
How many turns of ATP synthase are needed to bind ADP and Pi?
3
200
What are the functions of lipids?
```
Store energy
Structural component of cell membranes
Enzyme cofactor
Hormones
Synthesis of vitamins A,D,E and K
Signalling molecules
```
201
What are the major lipid classes?
Fatty acids
Triacylglycerides
Phospholipids
202
What is the structure of a fatty acid?
Hydrocarbon chain with carboxylic acid at one end
203
What are the categories of fatty acids?
Essential
Good
Bad
Really bad
204
What are essential fatty acids?
Fatty acids cannot we must ingest as we cannot synthesise them- we cannot synthesise carbon double bonds past carbon 9
205
What are good fatty acids?
Fatty acids high in polyunsaturated fat
206
What are bad fatty acids?
Fatty acids high in saturated fat
207
What are really bad fatty acids?
Trans fatty acids
208
What are triacylglycerols?
Esters of fatty acids and glycerol
209
What are the functions of triacylglycerols?
Major component of adipose tissue- act as insulation and dietary fuel
210
What are phospholipids?
Glycerol with two fatty acid tails an a phosphate group head
211
What is the function of phospholipids?
Form the basic structure of the cell membrane
212
How are triacylglycerols digested?
Through pancreatic enzymes in the small intestine
| Emulsion by bile salts and peristalsis
213
What are triacylglycerols digested by and into?
Pancreatic lipase into monoacylglycerols and two fatty acids
214
What are cholesterol esters broken down into?
Cholesterol and fatty acids
215
What are phospholipids broken down into?
Lysophospholipids and fatty acids
216
How are fatty acids transported round the body?
Fatty acids and cholesterol esters into chylomicrons which are released into the bloodstream
217
What happens when chylomicrons reach the tissues?
Hydrolysed to fatty acids and glycerol for uptake into the cell, for energy or storage
218
How are free fatty acids transported in the blood?
In a complex with serum albumin
219
Explain How fats are transported in high and low density lipoproteins
```
LDL= fat from liver to tissues
HDL= fat from tissue to liver for elimination
```
220
What is the beta oxidation pathway and where does it occur?
Degratation of fatty acids 2 carbons at a time
| Mitochondrial matrix
221
What are the 3 stages of the beta oxidation pathway?
Activation
Transport
Degradation
222
What happens in the first step of the beta oxidation pathway?
Fatty acids are activated to form fatty acylcoA in the cytoplasm
2 ATP used
223
What happens in the second step of the beta oxidation pathway?
Carnitine shuttle transfers long chain fatty acyl coA to the inside of the mitochondrion
224
What happens in the third stage of the beta oxidation pathway?
Fatty acyl coA is dehydrogenated to form FADH and an intermediate
The intermediate is then hydrated
The resulting intermediate is then dehydrogenated to give NADH and an intermediate
Thiolysis forms acetyl coA to feed into citric acid cycle
225
What is formed in fatty acid synthesis?
Acetyl coA
FADH
NADH
Carbon species 2 Cs shorter than original fatty acid
226
What are ketone bodies?
Fuel sources synthesised from acetyl coA that can fuek the brain, unlike fatty acids
227
Where does ketogenesis occur?
Liver
228
What are the main nitrogen containing molecules in the body?
Amino acids
Ammonia
Urea
229
What are the 3 types of protein digestion?
Gastric
Pancreatic
Intestinal
230
How are proteins digested in the stomach?
Denaturation of proteins males them more susceptible to actions of pepsin
231
How are proteins digested by the pancreas?
Pancreatic enzymes create a mix of free amino acids and short peptides around 2-8 units in length
232
How are proteins absorbed in the intestines?
Free amino acids absorbed into the portal system
| Di and tripeptides are absorbed and broken down to free amino acids in enterocytes of the brush border
233
What is different about glutamate compared to the other amino acids?
Can obtain its nitrogen from ammonia rather than preexisting amino acids through transaminase reactions
234
Describe the catabolism of protein
Once the proteins are broken down, they are deaminated and catabolised into intermediated of the citric acid cycle and glycolysis to be used as energy
235
How is nitrogen transported from the muscles to the liver?
Through the bloodstream as alanine
236
What happens to amino acids once in the liver?
Built up to form glucose, creating ammonia and urea and requiring the use of transferase enzymes
237
How is urea formed?
From ammonia in the urea cycle
238
How is ammonia formed?
Through oxidative deamination, where glutamate loses its nitrogen as ammonia
239
How is the nervous system organised?
Brain
Spinal cord
Peripheral nerves
240
How is the peripheral nervous system organised?
Autonomic- sympathetic and parasympathetic
| Somatic
241
Describe the general structure of neuron
Cell body- contains nucleus
Dendrites- route to other neurons
Axon- carries action potential
Terminals- connects with nerves/muscles
242
What is the resting membrane potential?
-70mV
243
How is the resting membrane potential created?
Na/K pumps pump K into cell and Na out
K channels allow K to leak out of cell via facilitated diffusion
There are therefore more positive ions outside the cell than inside the cell, creating the membrane potential
244
What are action potentials?
All or nothing signals that either fire a potential of +40mV or nothing
Intensity is shown in frequency, not amplitude
245
What are graded potentials?
Potentials that vary in intensity with the intensity of the stimulus
Can be depolarising or hyperpolarising
Can summate
246
How are nerve signals fired?
Once a graded potential reaches threshold, an action potential will be fired
This changes the potential of the neutron to +40mV, where the Na channels open and depolarise the cell
This then opens K channels, depolarising the cell
Na/K pump restores resting membrane potential
247
What are the 3 types of nerve fibres?
Afferent
Interneurones
Efferent
248
What is the function of the 3 types of neuron?
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Afferent= detect changes or sensory stimuli
Interneurones= Carry signal to brain
Efferent= carry signals to effector tissues or muscles
```
249
How does axon size affect transmission speed?
Larger axon=faster transmission
| Resistance is decreased, allowing the charge to travel further and reducing the time needed
250
How does myelination affect transmission speed?
Myelnation=faster transmission
| Transmission can travel further due to insulation provided
251
What is the neuromuscular junction and its structure?
Junction between the nerve and effects muscle
Synapse between the two
Muscular side has sarcolemma
252
Describe the process of neuromuscular transmission
Action potential opens Ca- channels in presynaptic terminal
Triggers fusion of vesicle and acetylcholine released into cleft
Diffused across synapse and binds to receptors in junctional folds
End plate potential reached and action potential fired
Each removed from cleft by acetycholinesterase
253
What are the main differences between neuron-neuron junction and neuromuscular junction?
Neuron-neuron= wide range of neurotransmitters, range of postsynaptic potentials, different anatomical arrangement, synaptic connectivity
254
What is the structure of skeletal muscle?
Multinucleated striated fibres collected in bundles and wrapped in sheathes
255
How do muscles contract?
Calcium ions bind to troponin on the actin filament and remove the tropomyosin, exposing the actin binding sites
The myosin converts an attached ATP to ADP and Pi and used this energy too bind to the actin
The myosin head then releases the ADP and unattaches
When Ca ions return to the sarcoplasmic reticulum, the tropomyosin again binds and the contraction stops
256
What is an isotonic muscle twitch?
Contraction with shortening length
257
What is an isomeric muscle twitch?
Contraction with constant length
258
What is tetanus?
State of extended contraction via the summation of action potentials
no respite in which Ca can return to sarcoplasmic reticulum
259
What is fatigue?
State caused by repeated muscle stimulation
260
What is the purpose of fatigue?
Prevents using vast quantities of ATP
261
What are oxidative fibres?
muscle fibres with more mitochondria and myoglobin
262
What are glycolytic fibres?
Muscle fibres with few mitochondria and a high concentration of glycolytic enzymes and glycogen
263
What is the structure of smooth muscle?
Mononucleate non striated spindles
| Diagonally arranged actin and myosin filaments
264
What are receptors?
Proteins that recognise a specific compound or molecule
265
What are agonists and antagonists?
Agonists mimic the effect of a receptor
| Antagonists block the normal action of a recteptor
266
Define the term affinity of a drug for a receptor
The strength of the chemical attraction between the drug and the receptor
267
What is the efficacy of an agonist?
How good an agonist is at activating a specific receptor
268
In what ways can receptors pass signals across the membrane?
Receptors that act as ion channels, interact with JAK kinases or G proteins, or have intrinsic enzyme activity
269
What are the types of G protein receptor and how do they work?
Adenylyl cyclase- change concentration of cAMP to activate or inactivate PKA
Phospholipase C- produce diacylglycerol and inositol triphosphate to activate PKC and release internal Ca-
270
What are the sources of intracellular calcium?
From internal stores
From transport via ligand or voltage gated channels into the cell
Via inhibition of Ca- transport out of the cell
271
What is the structure of cutaneous sensory receptors?
Nerve ending protected by capsule
| Stretch sensitive ion channels- present in distal tip of axon or in specialised sensory cells
272
How do cutaneous sensory receptors transmit a singal?
Stretch sensitive ion channels are activated, releasing a neurotransmitter to create a generator potential in the dendrites
273
Describe the concept of frequency coding
The bigger the stimulus, the greater the receptor potential and the higher frequency of action potentials
274
What are muscle spindles?
Intrafusal fibres that monitor muscle length and they way in which they contract
275
What is the structure of muscle spindles?
Intrafusal fibres containing sarcomeres, controlled by gamamotoneurones
276
What is the function of the golgi tendon organs?
Monitor muscle tension
277
How is muscle tension monitored?
The stretch in tendons- monitored by nerve endings- is directly related to muscle tension
278
Describe the stretch reflex
A sharp tap to the tendons, which are inelastic- so the force is transferred to the muscle which stretch and stimulate the spindles, activating alphamotorneurons and stimulating the agonist to contract
279
Describe the clasp knife reflex
As the muscle contracts, it pulls on tendons and the golgi tendon organs increase their discharge, activating inhibiting neurons to the agonist, decreasing contraction strength and activating the antagonist muscles
280
Describe the flexor-withdrawal reflex
Sensory stimulus from the nocireceptors causes an increase in the activity of flexor muscles via excitatory interneurons, and decreasing activity in antagonists via inhibitory neurons
281
What is important in the flexor-withdrawal reflex in the legs?
If one leg withdraws, the other must extend
| Excitatory interneurons crossing the spinal column, activating extensors and inhibiting flexion
282
Where does sympathetic and parasympathetic outflow originate from?
Sympathetics- thoracic-lumbar T1-L2
| Parasympathetic- Cranial sacral C3-5 and S1-5
283
What is the structure of sympathetic fibres?
Short preganglionic fibres, synapse in the sympathetic trunk, long postganglionic fibre
284
What is the structure of parasympathetic fibres?
Long preganglionic fibre, with synapse close to or in target organ
285
What neurotransmitters are used by sympathetic and parasympathetic fibres and what receptors do they act on?
All preganglionic release acetylcholine onto nicotinic receptors
Sympathetic postganglionic- noradrenaline on alpha or beta receptors
Parasympathetic postganglionic- acetylcholine onto muscarinic
286
What is the average circulating volume of an adult male?
5 litres- 1 in lungs, 3 in veins, 1 in heart and arteries
287
What are the functions of blood?
```
Carraige of physiologically active compounds
Clotting
Defence
Carriage of gas
Thermoregulation
Maintenance of ECF pH
```
288
What are the 3 plasma proteins?
Albumin
Globulins
Fibrinogen
289
What is oncotic pressure?
Concentration gradient of plasma proteins that draws water into the circulatory system
290
What is the structure and function of red blood cells?
Flexible, biconcave and non-nucleated
| Carry oxygen around the body in the blood
291
What is erythropoiesis?
The differentiation of pluripotent into erythroblasts, accelerate by erythropoietin
292
What are the 5 main types of white blood cells?
```
Neutrophils
Eosinophils
Basophils
Monocytes
Lymphocytes
```
293
What are neutrophils?
Phagocytic white blood cells that deal with bacterial infection
294
What are eosinophils?
White blood cells that attach pathogens too large for other leukocytes
295
What are basophils?
White blood cells that release histamine and heparin to promote inflammation
296
What are monocytes?
White blood cells that migrate to tissues and become macrophages
297
What are lymphocytes?
White blood cells that can either form B or T cells
298
What factors control white cell formation?
Cytokines- growth stimulating factors, interleukins
299
What are platelets?
Membrane bound fragments of megakaryocytes
300
What is the function of platelets?
Adhere to damaged capillary walls and exposed connective tissue to mediate blood clotting
301
What is haematocrit?
Proportion of red blood cells in the blood
302
What is blood viscosity?
Thickness of the blood in comparison to water- plasma is 1.8x thicker, whole blood is 3-4x thicker
303
What are the major cells involving innate immunity?
Macrophages
| Neutrophils
304
What are the major cells involved in adaptive immunity?
Lymphocytes
305
What is the role of the innate immune system?
Act as the body's first line of defence
306
What factors are involves in the innate immune system?
Physical barriers
Phagocytic cells
Soluble factors
307
What is the process of phagocytosis?
Foreign matter is internalised by cytoplasmic vesicles
| Matter is digested by lysosomes which contain enzymes
308
What are the primary and secondary lymphoid organs?
Primary- where lymphocytes are created, thymus, bone marrow, foetal liver
Secondary- where immune responses are initiated and lymphocytes maintained, lymph nodes, spleen
309
What are the fundamental properties of the adaptive immune response?
Specificity
Diversity
Memory
Recruitment of other defence mechanisms
310
What is the role of B lymphocytes?
Form plasma cells
| Synthesise antibodies
311
What is the structure and function of an antibody?
Y shaped protein
paratope= antigen binding region
Coat surface of antigen to prevent entry to cell, stimulate other parts to the immune system, opsonisation
312
What is the complement system?
System made of 25 serum proteins that can cause
- recruitment of inflammatory cells
- opsonisation of bacteria
- lysis of bacteria
