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Cellular Physiology Flashcards

1
Q

Common types of interactions between cells

A

Mechanical
Electrical
Chemical - neurotransmitters, neurohormones, endocrine, paracrine, autocrine

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2
Q

How might control be exerted on an intracellular function? 5

A

Activation or inhibition of enzymes
Regulation of gene expression
Changes in membrane permeability
Regulation of membrane receptor activity
Changes in membrane potential

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3
Q

What is cytoplasm

A

Everything outside the nucleus within the cell

Cytosol (water, proteins, electrolytes) and organelles

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4
Q

Components of cytoskeleton - diameters

A

Microtubules - 25nm
Muscle thick filaments - myosin - 15nm
Intermediate filaments - 10nm
Muscle thin filaments - actin - 5nm

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5
Q

What is the function of the cytoskeleton?

A

Cell structure
Cell movement
Cell shape changes

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6
Q

Contents of mitochondria with function

A

To produce ATP
folded inner membrane - cristae - oxidative phosphorylation enzymes
Matrix - citric acid cycle
Maternal DNA

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7
Q

Function of endoplasmic reticulum

A

Rough - protein synthesis
Smooth - steroid synthesis and detoxification

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8
Q

Ribosome size and makeup, location
Function

A

32nm
65% RNA, 35% protein
On rough er or loose in cytoplasm
Protein synthesis

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9
Q

Function of centrosome

A

Formation of mitotic spindle

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10
Q

Function of golgi
Name of sides

A

Prepare proteins for secretion by exocytosis
Cis (receives proteins from ER) and trans (produces vesicles to travel to cell membrane)

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11
Q

Classifications of cell junction and function, example

A

Anchoring junction - form cell cell adhesions and allow anchoring of cytoskeleton e.g. desmosome
Occluding junction - seals the extracellular space preventing passage of molecules - eg tight junction
Channel forming junction - allow for passage of small molecules between cells - e.g gap junction
Signal relay junctions - allow communication between cells

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12
Q

Function of lysosomes and peroxisomes

A

Lysosomes breakdown and eliminate intracellular debris or exogenous substances
Persoxisomes catalyse anabolic and catabolic reactions

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13
Q

Function of cilia
Composition
Function

A

Move substances across surface of cell
9 pairs of microtubules around a central pair (10 in total)
Molecular motor mechanism causing micro tubules to slide relative to each other

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14
Q

Functions of cell membrane

A

Regulation of passage of substances maintaining homeostasis
Establishment of concentration gradients
Generation of action potentials
Contain cell contents
Anchor cytoskeleton
Site of intercellular connect
Communication - chemical and electrical

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15
Q

Term for the polar nature of phospholipids with regards to water sensitivity

A

Amphipathic

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16
Q

What is the term for the glycoprotein coat attached to membrane proteins across the cell

A

Glycocalyx

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17
Q

Categories of protein in a cell membrane by position

A

Integral vs peripheral
Transmembrane vs monotopic

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18
Q

What are the cell adhesion molecules

A

Membrane proteins with wide range of functions including adherence to other cells or surfaces and signal transduction

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19
Q

What proteins are responsible for adhesion to other cells? Which to the extracellular matrix?

A

Cells - Cadherins
Matrix - integrins

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20
Q

Physiological and pathological processes involving cadherins

A

Morphogenesis
Metastasis
Embryogenesis

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21
Q

Physiological processes associated with integrins

A

Platelet adhesion
Leukocyte mobility
Cell matrix adhesion

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22
Q

Subunits of a G protein

A

Alpha beta and gamma

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23
Q

Activation and deactivation sequence of a G protein

A

Ligand binds to GPCR,
release of GDP from alpha subunit, GTP binds in place,
dissociation of G protein,
Alpha subunit interacts with effector
GTP broken down by intrinsic GTPase,
deactivation of G protein

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24
Q

Number of G protein coupled receptor transmembrane domains

A

7

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25
Common GPCRs
Adrenoreceptors Muscarinic ACH receptor Opioid receptor
26
Types of G protein and downstream effect
Gs - stimulates adenylyl cyclase increasing cAMP - stimulates PKA (a protein kinase) causing target phosphorylation Gi - inhibits adenylyl cyclase decreasing cAMP Gq - stimulates phospholipase C cleaving PIP2 into IP3 (opens Ca channels) and DAG (stimulates protein kinase C causing target phosphorylation)
27
What substances can cross phospholipid bilayer
Water, lipid soluble substances, small molecules
28
Define diffusion
Movement of solute molecules due to random thermal motion with a net movement down concentration gradient (high to low)
29
Factors that influence diffusion across cell membrane
Concentration gradient Surface area Membrane thickness Temperature Lipid solubility Molecular weight Electrical charge of particle
30
Define osmosis
Net movement of water molecules due to diffusion between areas of different concentration Can consider addition of a solute as diluting the water and reducing its concentration thus water diffuses from a high concentration (low concentration of solute) to low concentration (high concentration of solute)
31
What is osmolarity
Concentration of solution. 1 mole/litre = 1 osm/L
32
Define osmotic pressure
The pressure required to oppose the net movement of water across a semipermeable membrane between two solutions
33
What is the osmolarity of ECF normally?
300mOsm/L
34
What is tonicity? What does it depend on?
The ability of a solution to cause shrinkage or swelling of a cell placed in it. ECF and ICF osmolarity Cell membrane permeability to the solute particles.
35
Types of gated ion channels
Stretch (mechanically gated) Chemical (ligand gated) Electrical (voltage gated)
36
What sort of carriers are there for active transport (by substance exchange method)
Uniport - carries one specific substance Symport - transports combination of substances Antiport - exchanges one substance for another
37
What occurs with membrane proteins when they facilitate active transport? What is the impact of this on transport speed, what else contributes?
They undergo a conformational change - speed is in part determined by how fast they can change. Also how dense the carriers are and how saturated they are.
38
Features of NaKATPase
Primary active transporter Uses ATP to phosphorylate Antiporter exchanging 3 Na for 2 K both against concentration gradient
39
Define primary and secondary active transport
Primary - use of energy directly at carrier proteins Secondary - uses an ion gradient set up by primary active transport in order to facilitate the transport of another molecule - substance binds at first carrier site, ion binds at a secondary site on the protein, allosteric modulation causes transport of substance whilst ion travels down diffusion gradient.
40
What are the two sorts of secondary active transport
Co transport - ion and substance carried in same direction Counter transport - ion and substance carried in opposite directions
41
What is facilitated diffusion? Difference and implication to normal diffusion?
Transport of a substance down concentration gradient via a carrier. Not a diffusion mechanism - no energy is required but transport kinetics are characteristic of carrier mediated transport Thus carrier saturation occurs limiting rate.
42
What are exo and Endocytosis
Transport of substances by fusion of membrane covered vesicles with cell membrane
43
What surrounds the nucleus Features
Nuclear envelope Double membrane with nuclear pores that allow passage of specific proteins
44
What is the function of the nucleolus
Synthesis of ribosome subunits.
45
Components of a nucleotide
Base (Purine/pyramidine) Sugar (ribose or deoxyribose) Phosphate group
46
Bases in DNA
Adenine Guanine Cytosine Thymine
47
Three types of rna
Messenger Transport Ribosomal
48
What is the main sort of rna in a cell?
Ribosomal - constitutes 2/3rds of ribosome
49
Number of chromosomes in human
23 pairs
50
What is chromatin
The clumped dna protein complex seen in the nucleus
51
Phases of mitosis
Prophase - separation of centrioles and formation of chromosomes from chromatin Prometaphase - nuclear membrane and nucleolus disitigrates Metaphase - chromosomes line up on cell equator Anaphase - chromatids split Telophase - chromosomes, nuclear membrane and nucleoli reform, cytokinesis begins
52
Which enzyme is instrumental to transcription
RNA polymerase
53
Which enzyme is instrumental for Translation
Aminoacyl-tRNA synthetase
54
How many tRNAs are bound to mRNA at any one time during translation? What are they doing?
2, once carrying the amino acid chain, an adjacent one carrying the next amino acid.
55
What are the regions of DNA? Which are used for protein synthesis?
Introns - cut out in post transcription processing of pre-mRNA into mRNA Exons - used
56
What are transcription factors
Controlling factors that influence RNA polymerase binding to certain (one or multiple) genes. Can originate in the cell or external to it.
57
Other than transcription factors how else can protein synthesis rate be controlled
At the translation stage Controlling mRNA breakdown
58
Classifications of first chemical messengers between cells
Neurotransmitters Neuromuscular transmitters Endocrine agents Paracrine agents Autocrine agents
59
Definition of ligand affinity
Strength of binding with receptor
60
Definition of ligand competition
Ability of different ligands to bind with same receptor
61
Definition of ligand agonist
Ability of ligand to trigger cell response
62
Definition of ligand antagonist
Ability of ligand to bind to receptor without triggering a response
63
Definition of ligand half life
Time take for ligand to be metabolised to half its concentration
64
Consequence of ligand lipid solubility
Lipid insoluble ligands active cell surface receptors Lipid soluble ligands active intracellular or intranuclear receptors
65
Definition of receptor specificity
Selectivity of a receptor to a single ligand
66
Definition of receptor saturation
Percentage of receptors already occupied by ligand
67
Definition of receptor down regulation and up regulation
Decrease / increase in number of receptors available for given ligand
68
Definition of receptor sensitivity What controls it
Responsiveness of a get full to given ligand - dependant on concentration of receptors
69
Definition of receptor supersenstitivity
Increased sensitivity of cell due to receptor upregulation
70
What are the two processes that allow ligand binding to receptor with conformational change? Brief desription
Allosteric modulation - separate modulator binds away from binding site resulting in conformational change allowing ligand binding Covalent modulation - phosphorylation of receptor with conformational change allowing ligand binding.
71
Group of proteins responsible for phosphorylation
Kinases
72
What ways might a receptor result in signal transduction into the cell?
Opening or closing of integral ion channel Activation of intracellular protein kinase Activation of G proteins mediating further action
73
How can lipid soluble ligands exert their intracellular effect
Complex formation with cytosol receptor which moves to nucleolus and promotes gene expression Ligand moves directly into nucleus and forms complex with nuclear receptor and promotes gene expression,
74
What is the effect of the second messenger system within a cell on signals strength
Acts as a cascade amplyfing the signal
75
What is the effect of caffeine and theophylline on the second messenger system?
Inhibit phosphodiesterases reducing breakdown of cAMP and cGMP augmenting the second messenger cascade.
76
What is the approx gradient of extracellular to intracellular calcium concentration? Implication?
10^4 Rapidly enters cell when given chance
77
Where is calcium stored intracellular
ER
78
How are calcium levels reduced in the cell
C H ATPase NaCa Antiporter Reuptake into ER
79
Examples of intracellular proteins that calcium can bind to Other functions when released
Calmodulin Troponin Calbindin Synaptic function Protein synthesis
80
What occurs downstream after binding of calcium to calmodulin
Acts as a protein kinase
81
Effect of IP3 production from G proteins
Release of calcium from ER
82
Mediator that is activated by Gq receptors causing cleavage of PIP2 to IP3 and DAG
Phosphlipase C
83
Effect of DAG
Activation of protein kinase C
84
Definition of aging
Physiological process involving general changes in body systems (usually decline) distinct from the pathological changes of disease
85
Three theories of aging
Wear and tear - natural deterioration as a result of continuous functioning Adaptive evolution - genetically programmed termination of life in interests of evolutionary selection Non-adaptive evolution - evolved as optimum balance between limited energy sources available and demands of normal function and repair
86
Cellular mechanisms associated with ageing
Accumulation of cells with random mutations Crosslinking of collagens and proteins by glycosylation Accumulation of oxidant radicles and lipofuscin granules Genetic clock determining number of cell reduplications Pleiotropic genes with good effects in early life and bad in later life
87
Cardiac output and renal blood flow of a 70 year old vs young adult
64 and 60%
88
Muscle mass of a 70 year old vs young adult
74%
89
Cardiovascular changes in aging
Lower cardiac output and reserve Decreased heart rate Decreased stroke volume Decreased LV compliance
90
Respiratory effects of aging
Decreased pao2, lung elasticity, compliance, vital capacity Increased residual volume
91
Gi changes with age
Decreased smell and taste Decreased coordination and swallowing Decreased gastric and pancreatic secretions Decreased large bowel motility
92
Endocrine effects with aging
Increased norad and vasopressin Decreased RAAS, carbohydrate tolerance, oestrogen and testosterone
93
Renal changes with ageing
Decreased kidney mass, ability to concentrate urine, renal response to vasopressin Increased prostate mass
94
CNS changes with ageing
Decreased brain mass, ACh activity, cerebral blood flow, short term memory Increased reaction time
95
Immunological change with ageing
Decreased cellular and humoral immunity
96
Musculoskeletal changes with ageing
Decreased bone and muscle mass

Primary Physiology (15 decks)

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