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Physiology > Cell Biology > Flashcards

Cell Biology Flashcards

1
Q

What is the significance of the cell membrane being a phospholipid bilayer?

A

It means that only lipidic or fat-soluble substances can diffuse through such as vitamins. Therefore water-soluble substances such as ions must have their passage through the membrane facilitated.

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2
Q

Define Passive Transport

A

When their is no energy required to pass through the membrane, such as when following a concentration gradient.

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3
Q

Define Active Transport.

A

When energy is required to pass a substance through a membrane.

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4
Q

What is the source of energy in active transport?

A

ATP - Adenosine Tri Phosphate

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5
Q

What are the 3 main mechanism for passive transport?

A

Passive diffusion, channel/transport protein-mediated substance facilitated transport.

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6
Q

Define Channel-mediated passive transport.

A

This form of transport only carries ions across a membrane and is exclusively passive. Its main benefit is that it can allow large numbers of ions to move across a membrane rapidly.

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7
Q

What are the 3 states of the ion channel

A

Resting (Closed)
Open
Ball & Chain mediated inactivation

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8
Q

What stimuli may open an ion channel?

A

Substance or ligand-gated open up when bound by a hormone or neurotransmitter.
Change in voltage can open other ion channels

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9
Q

Define Secondary Active Transport.

A

Where one substrate uses a concentration gradient of another substrate in order to facilitate its movement across a membrane and against the concentration gradient.

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10
Q

Define Primary Active Transport.

A

Where a substrate is enabled to cross a membrane against their concentration gradient through ATP degradation.

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11
Q

What is another term for Secondary Active Transport?

A

Cotransporter or coupled transporter

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12
Q

What is ATP broken down into when undergoing transport hydrolysis?

A

ATP is broken down into Adenosine di phosphate (ADP) and phosphate (PO4)

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13
Q

Which is more common active or passive transport?

A

Passive transport although disease processes are more likely to disrupt active transport and cause symptoms.

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14
Q

Define homeostasis.

A

The regulation of keeping the body in its normal environment through involuntary neuronal and hormonal controls.

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15
Q

Define pathological homeostasis

A

Where the body maintains a pathological normal balance and will try and correct and interventions you use to fix this eg high blood pressure and blood glucose

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16
Q

What is the equation for total body water?

A

TBW = 0.6 x Body Weight

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17
Q

How do you work out ECF?

A

ECF = 0.2 x Body Weight

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18
Q

How do you work out ICF?

A

ICF = 0.4 x Body Weight

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19
Q

How do you work out Interstitial Fluid?

A

Interstitial Fluid = 3/4 of ECF

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20
Q

How do you work out Plasma volume?

A

Plasma = 1/4 of ECF

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21
Q

Define diffusion.

A

Solute movement from a higher concentration to a lower concentration until it equilibrates if allowed to.

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22
Q

Define Osmotic Pressure

A

A concentration gradient caused by an unequal distribution if ions across a semi-permeable membrane causing water to move towards the higher electrolyte concentration.

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23
Q

Define Oncotic Pressure

A

A concentration gradient caused by the unequal distribution of macro molecules such as proteins and polysaccharides, across a membrane. It has a very strong water pull and is responsible for keeping water in the blood vessels

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24
Q

Define hydrostatic pressure.

A

Blood pressure - the pressure which fluid is pushing against the vessel walls

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25
Q

Name so causes of fluid extravasation .

A
  • increased BP
  • blocked lymph drainage
  • inflammation
  • Liver failure
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26
Q

Name some causes of fluid retention.

A

Renal Failure

Hypernatremia

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27
Q

What are the characteristics if a cell membrane?

A
  1. Permeable to water
  2. Impermeable to water soluble substances
  3. Permeable to fat soluble substances
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28
Q

What is a ligand?

A

A substance that binds to a receptor and elicits a response

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29
Q

What is an example of something that binds to an intracellular receptor?

A

Binds steroids

30
Q

What typically binds to an extracellular receptor?

A

Things that are too large to go through the membrane such as proteins and peptides

31
Q

What is a receptor?

A

Is a protein structure that binds ligands

32
Q

What is the clinical significance of receptor and their subtypes?

A

If a drug targets a receptor and all it’s subtypes they will have more widespread side effects

33
Q

Define endocytosis.

A

The taking in of a substance by a cell by invagination of its membrane to form a vacuole. The substance maybe released into the cell and utilised by leave the cell the other side via exocytosis.

34
Q

Define exocytosis.

A

A substance leaves a cell by the vacuole containing it moving to the outer membrane of the cell and fusing with it, thus liberating the substance to the extra-cellular environment.

35
Q

Define transcytosis

A

The transfer of a substance across a cell using endocytosis and exocytosis. Most commonly used by barrier tissues to transport larger substances over membranes.

36
Q

What is the function of the rough endoplasmic reticulum?

A

Protein synthesis occurs here by taking the RNA code and translates it into the correct amino acids sequence

37
Q

What is the function of the Golgi apparatus?

A

It package the protein into a membrane package readying it for export from the cell and transferred to other organelles or out of the cell

38
Q

What is the function of the mitochondria?

A

Production of energy from glucose. Also house drug metabolising enzymes

39
Q

What is the function of centrioles?

A

They form the centres for mitotic spindles which are key for cell division.

40
Q

What is an epithelial cell?

A

Cell that is exposed to the external environment.

41
Q

Define endothelial cells.

A

Cell surface that has direct contact with blood vessels

42
Q

What substances tend to be transported via exocytosis?

A

Hormones and neurotransmitters

43
Q

Define Pharmacodynamics.

A

Examines how drugs interact with the body.

44
Q

Give examples of structures that drugs target in the body.

A 
Ion Channels
Ion Pumps
Receptors
Enzymes
Cell Membranes
45
Q

What are the main forms of stimuli that open ion channels?

A

Ligands and voltage.

46
Q

What is the purpose of an ion pump?

A

Ion pumps move ions against the concentration gradient via active transport.

47
Q

Define receptor.

A

A receptor is a specific protein capable of binding the members of a specific drug or endogenous substances.

48
Q

Define enzyme.

A

Enzymes are chemical catalysts that accelerate biochemical reactions in the body.

49
Q

Name 2 common enzymes in the body.

A

ACE (Angiotensin Converting Enzyme) and COX (Cycloxygenase Enzyme)

50
Q

What does ACE do?

A

It is an enzyme that converts angiotensin I to angiotensin II

51
Q

What does COX do?

A

It is an enzyme that converts arachidonic acid into steroidal inflammatory mediators

52
Q

Define Agonist.

A

Drugs with high affinity and have high intrinsic activity

53
Q

Define Antagonist.

A

Drugs with high affinity but have no intrinsic activity. Therefore the binding of drugs to the target results in no effect as the receptor is inhibited.

54
Q

Define Affinity.

A

Affinity is a link between how the shape and charge of a ligand fit into the binding site of a receptor. The more the charges on the ligand complement receptor, the higher the affinity.

55
Q

Define Competitive Antagonist.

A

These drugs compete for the same receptor as an agonist.

56
Q

Define Non-competitive antagonist.

A

These drugs bind to a place other than the endogenous ligand binding site and incapacitance the receptor causing an absent biological effect.

57
Q

Define Partial Agonist.

A

These drugs act on a receptor without a maximum effect as an effect.

58
Q

Define relative affinity.

A

When the drug and the natural ligand compete for the same site, the comparative bind of one compared to the other is determined by relative affinity

59
Q

How does chemical concentration affect affinity?

A

If the drug and ligand have equal affinities then the concentration of the chemicals at the receptor. Therefore the effect of a competitive antagonist drugs can be stopped by flooding the system with an agonist for the receptor.

60
Q

Give some examples of receptors and their natural ligands.

A

Adrenoreceptor - Adrenaline
Cholinergic receptor - Acetylcholine
Dopamine receptor - Dopamine

61
Q

Give an example of an adrenergic receptor subtype.

A

alpha and beta receptors

62
Q

What are the effects of beta 1 receptors?

A

Largely stimulatory effects when adrenaline binds e.e increased cardiac and brain function

63
Q

What are the effects of beta 2 receptors?

A

Reduction in stimulation e.g. smooth muscle relaxation in the bronchi, blood vessels and bladder

64
Q

What factors affect capillary pressures?

A

Lymphatic re-absorption…

65
Q

What are triggers for ion channel opening?

A
  • Voltage
  • Ligand gated
  • Metabotropic:
    - G-protein Linked
    - Tyrosine Kinase
66
Q

What is the function of the nucleus?

A

It is the control centre for the cell an holds genetic information in DNA

67
Q

What are examples of triggers for an ion channel opening?

A 
Voltage
Ligand gated
Metabotrophic
- G-protein linked
- Tyrosine kinase
68
Q

What is the function of the nucleus?

A

It is the control centre for the cell and holds genetic information in DNA form for use by the cell.

69
Q

What substances tend to use endo or exocytosis?

A

Large protein-based substances such as hormones and neurotransmitters

70
Q

How do small molecules tend to be transported?

A

Small molecules such as glucose tend to be transported via transport proteins

Physiology (12 decks)

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