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Biol125 - Human Physiology > Week 2 > Flashcards

Week 2 Flashcards

(98 cards)

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1
Q

What is acetyl coA synthesised from ?

A

Acetyl coA + Choline using the enzyme choline acetyltransferase

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2
Q

What is the function of acetylcholinesterase ?

A

Break down acetylcholine - to prevent overstimulation

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3
Q

What 2 main types of receptors does acetylcholine bind to ?

A

Nicotinic - neuromuscular junction , brain , autonomic nerves
Muscarinic - smooth muscle , exocrine glands, brain

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4
Q

What are some of the neuropathological changes involved with Alzheimer’s disease ?

A

Loss of brain weight
Enlargement of ventricles
Numerous senile plaques
Neurofibrillary tangles

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5
Q

How can AChE inhibitors be used as treatment for AD?

A

Breaks down acetylcholinesterase
More acetylcholine in the brain

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6
Q

What are some AChE inhibitor drugs ?

A

Donepezil
Rivastigmine
Galantamine

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7
Q

How are catecholamines synthesised ?

A

From tyrosine
Involves enzymes monoamine oxidase (MAO) and catechol 0-methyltransferase (COMT)

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8
Q

When is the mean onset of Parkinson’s disease ?
What % does it affect ?
What is it characterised by ?

A

60 years
1-2% of over 65 yrs
Muscle stiffness
Slowness of movement
Tremor at rest

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9
Q

What % of dopamine is lost usually when symptoms of Parkinson’s are recognised ?

A

50%

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10
Q

What is the reason for Parkinson’s disease ?

A

Degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta and loss of dopamine in the caudate-putamen

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11
Q

What do selective serotonin reuptake inhibitors (SSRIS) do?
What can they help reduce the symptoms of ?
What are some examples ?

A

block the action of SERT = more serotonin at the synapse
Depression , anxiety , OCD , PTSD etc
Citalopram
Escitalopram
Fluoxetine
Paroxetine

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12
Q

How is Parkinson’s disease treated ?

A

Motor symptoms of PD are alleviated by treatment with L-Dopa which is transported into the brain and converted to dopamine
Administration of a peripherally active Dopa decarboxylase inhibitor prevents premature conversion of L-Dopa to dopamine
Inhibitors of COMPT and MAO-B can also be given to inhibit dopamine degradation

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13
Q
A
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14
Q

Are amino acid transmitters non-essential or essential ?
Which are excitatory and which are inhibitory ?

A

Non-essential
Glutamate , aspartate - excitatory
Glycine and GABA - inhibitory

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15
Q

Describe GABA A and GABA B

A

A - ionotropic receptor coupled to Cl- channel, has modulatory binding sites for benzodiazepines , barbiturates , neurosteroids and ethanol

B - metabotropic receptor coupled to Ca2+ and K+ channels via G proteins and second messenger systems

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16
Q

How can memantine be helpful for treating Alzheimer’s disease ?

A

Blocks Mg2+ binding site on the glutamate NMDA receptor
Preventing neuronal dysfunction and cell death

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17
Q

Give an example of a nicotinic agonist and antagonist ?

A

Nicotine (tobacco) - agonist
Curare (paralysis and poison) - antagonist

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18
Q

Give an example of a muscarianic agonist and antagonist

A

Agonist - muscarine (toadstool)
Antagonist - Atropine ( deadly nightshade )

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19
Q

How many major families of dopamine receptors are there ?

A

D1- like - coupled to stimulatory G-proteins
D1, D5
D2 like - coupled to inhibitory G proteins
D2, D3, D4

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20
Q

What is the most common type of neurotransmitter in the hypothalamus ?

A

Peptide neurotransmitters

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21
Q

How is serotonin synthesised ?

A

From tryptophan by tryptophan hydroxylase and 5-hydroxytryptophan (5-HTP) decarboxylase

Broken down into 5-hydroxyindoleactic acid ( 5-HIAA) by MAO and aldehyde dehydrogenase

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22
Q

How many receptors and what types of receptors can serotonin bind to ?
How is action terminated ?

A

14
All G-protein-coupled -except for 5-HT3 which is a ligand-gated ion channel
Action terminated mainly by reuptake from the synapse via the 5-HT transporter on the pre synaptic neuron.

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23
Q

How is GABA synthesised from glutamate ?

A

Using glutamate decarboxylase
Vitamin B6

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24
Q

What are the different types of Glutamate receptor , what do they bind and do ?

A

NMDA receptor - binds glutamate , glycine , Mg2+ , Zn2+ and polyamines. Form channels that are permeable to cations
Non-NMDA receptors - Kainate and AMPA receptors interact only with glutamate and their specific agonists (Na+ , K+ > Ca2+ )
MGlut receptors - G-protein coupled receptors and trigger a second messenger cascade (eight different types of mGLuRs)

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25
How is glutamate removed from the synapse ? Is this similar to GABA uptake ?
By astrocyte uptake via excitatory amino acid transporters GABA is also taken up in this way , both are catabolised to glutamine which is then transported to the neurons for re-use
26
What type of agonist is given as treatment of seizures in epilepsy ?
GABA receptors
27
Peptide neurotransmitters are synthesised as large precursor proteins and transported to the synaptic release site what is this activated by ?
Proteolytic cleavage
28
What terminates actions with peptide neurotransmitters and what are they often co-released with ?
Extracellular proteases Classical transmitters
29
What does NO gas ) neurotransmitter do ?
Diffuses from nerve terminals into adjacent cells and forms covalent linkages to a multiplicity of targets , which may be enzymes or other targets
30
How long is the GI tract in living and at autopsy ? Functions ?
4.5 m (living ) , 9m autopsy Digestion - physical and chemical breakdown of food Absorption- transport of digestive end-products in to bloodstream Motility - peristaltic activity of muscle , propelling food along GI tract Accessory glands - salivary , pancreas , liver hall bladder Secretion - transport of digestive fluids into the GI tract
31
What are the different sphincters in the digestive tract ?
Upper esophageal sphincter Lower esophageal sphincter Pyloric sphincter Ileocecal sphincter Anal sphincter
32
What is the mucosa layer of the GI tract composed of ?
1. Mucosa (epithelium , lamina propria , muscular mucosa )
33
What is the submucosa layer of the GI tract composed of ?
2. Submucosa (connective tissue , blood and lymphatic vessels )
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What is the muscularis composed of in the GI tract ?
Circular layer Longitudinal layer
36
What is the serosa layer of the GI tract ?
Connective tissue
37
What are the 3 layers of the GI mucosa ?
membrane, lamina propria (connective tissue, capillaries, nerves, lymphoid tissue) and muscularis mucosae
38
What is the mucous membrane of the mucosa layer composed of ?
39
How long is the oesophagus ? Are the upper and lower esophageal sphincters usually closed ? Type of muscle ?
25 cm long Muscular tube Yes, they are usually closed, backflow can cause heartburn Upper - 1/3 skeletal Lower - 2/3 smooth muscle
40
How large is the stomach ? What cells do gastric glands contain ?
50ml to 1-2 L Can expand Parietal cells - secrete HCl and chief cells secrete pepsinogen
41
What volume of HCl can the stomach secrete a day ?
2 litres
42
What is intrinsic factor ?
glycoprotein required for absorption of vitamin B12 in the ileum
43
What does rennin do ?
coagulates milk
44
How is HCL produced in the lumen ?
H+ ions, made from CO2 and water by carbonic anhydrase (CA), are actively transported into the lumen in exchange for K+ ions Bicarbonate ions are exchanged for chloride ions, which diffuse into the lumen Nett result is the accumulation of HCl in the lumen
45
What do the hormone gastrin and the vagus nerve trigger the release of ?
Pepsinogen and HCl
46
What is a zymogen ?
Pre enzyme so that the stomach is not damaged by the enzyme
47
How is pepsinogen activated ?
Pepsinogen is not activated until it encounters HCl in the stomach The first 44 amino acids of pepsinogen are removed to generate pepsin Pepsin can then activate more pepsinogen Pepsin exhibits maximal activity at pH 2.0 and is inactive at ≥ pH 6.5 Pepsin is an endopeptidase that starts to break internal peptide bonds of proteins to generate smaller fragments Exopeptidases remove one amino acid at a time from either end of a polypeptide
48
How long is the small intestine ? What are the 3 regions ?
Approx 2.5-3m long Duodenum , jejenum , ileum
49
What does the duodenum receive ?
chyme from stomach, enzymes from pancreas, and bile from liver & gallbladder
50
What do crypts of Lieberkuhn do ?
secrete copious amounts of bicarbonate-rich fluid to neutralise chyme from the stomach
51
What does the colon consist of ? Function ?
Cecum, rectum, anal canal, also includes the appendix which is attached to the cecum Crypts of Lieberkuhn , no villi Principle site of water absorption Principle location of commensal microflora in
52
How many litres/day saliva are produced /day ?
0.75-1.5L
53
What is saliva stimulated by ?
The autonomic nervous system
54
What enzymes does saliva contain ? What are the other functions of saliva ?
Salivary a-amylase (digests glycogen and starch) and lingual lipase Lubrication ( mucus ) Buffering and diluting noxious substances Antibiotic action (lysozyme, lactoferrin ) Taste Cleans teeth Fluoride , calcium uptake into teeth
55
Where does the pancreas feed its products into?
Into the duodenum
56
How long is the pancreas? What cell type make digestive enzymes ?
About 20cm long , weighs -100g Made by acinar cells , released into duodenum via secretory duct
57
What zymogens does the pancreas produce ? What other enzymes are produced ? What do acinar cells also produce ?
Chymotrypsin , trypsin , carboxypeptidase , elastase made as zymogens Pancreatic amylase (digests starch) , lipase , proteases , DNase , RNASe Bicarbonate
58
What do the islets of Langerhans make ?
Hormones which are secreted into the blood
59
What do Beta , Alpha , delta Cells do?
B - insulin production glucose —-> glycogen A- glucagon - glycogen ——> glucose Delta cells - Somatostatin regulates digestion , absorption and release of other hormones
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67
How is insulin produced from proinsulin ?
4 amino acids are removed leaving the A and B chains , plus the C-peptide
68
What is the cause of Type 1 diabetes ? How is it treated ?
(Early onset , insulin dependent ) autoimmune disease caused by the loss of insulin secretion from the islets of Langerhans Treated with insulin administration
69
What is the cause of type 2 diabetes ?
Late onset - non-insulin dependent , associated with obesity , sedentary lifestyle , due to an initial loss of responsiveness to insulin , followed by a reduced insulin secretion
70
Fats are emulsified into fat droplets by ……… then they are susceptible to digestion by ………..
Bile salts Pancreatic lipase
71
Resulting long chain fatty acids and monoglycerides are converted into ……………. (small particles) , which enter the ………… system Some small short-chain fatty acids are absorbed straight to the ……….. instead of the lymph
Chylomicrons Lymphatic (drains into blood in left subclavian vein in the neck) Blood
72
Where has the highest microbiota concentration ? (10 to the power of 12 ml)
The colon
73
Where does the thoracic duct drain to? Where does the mesenteric lymph vessels drain to ?
Into the left subclavian vein Mesenteric lymph vessels
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75
Through which veins do monosaccharides, amino acids, electrolytes, water, absorbed from the intestines travel to the liver ? They can then enter the general circulation via the hepatic vein
Mesenteric veins Hepatic portal vein
76
What are the functions of biological catalysts ?
Regulate the flow of molecules through all metabolic pathways Build structures of cells (and break them down again ) Break down invading pathogens and parasites
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78
What are some uses of biological catalysts ?
Washing tablets Denim manufacture Used in food Cheese
79
Where do monosaccharides and amino acids go after digestion ?
Absorbed into the blood stream ( capillaries ) of liver , then to the liver ( via the hepatic portal vein )
80
Are all enzymes proteins ?
No, most are but there are ribozymes ( ribonucleic acid enzymes ) - self splicing RNA ( removes introns)
81
Do different enzymes have different substrate specificities?
Yes, e.g subtilisin is a bacterial protease that cleaves peptide bonds indiscriminately and some have really high specificity such as thrombin which cleaves between Arg and Gly within specific amino acid sequence motifs
82
Most enzyme names end in -ase , what are exceptions
Proteolytic enzymes that end with ‘in’ e.g trypsin , pepsin
83
What are enzyme commission numbers ? In the form 1.2.3.4
1st digit = 6 major classes Second and third digits give further details for the type of reaction ( bonds and groups ) Fourth digit gives substrate ( general descriptor , e.g amino acid enzymes, nucleic acid, lipid, etc )
84
What is the SI unit for enzyme activity ?
kayak (kat) = the amount of an enzyme that converts 1mol of substrate per second under standard assay conditions International activity unit (U) An amount of enzyme that will catalyse the transformation of 1 µ mole of the substrate per minute under standard assay conditions International
85
What is the equation for K eq ( K equilibrium ) ?
K eq = k for / k rev
86
What term describes reactions which release energy to the surroundings?
Exergonic
87
What term describes reactions which require an overall input of energy ? Why do most exergonic reactions still need an initial spark of energy ?
Endogonic Collision and bond destabilising
88
What is delta G
Difference between free energy of the products and the free energy of the products and the free energy of the reactants
89
At the summit the molecules are at an unstable state what is this called ? What is the difference between the free energy of the reactants and the transition state ?
Transition state delta G (double dagger ) - change in gibbs free energy of activation
90
How do enzymes reduce activation energy ?
Helping to form the transition state
91
What is energy contributes by binding of active site to transition state is equivalent to ?
Delta G B

Biol125 - Human Physiology (4 decks)

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