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Health And Society > Week 5 > Flashcards

Week 5 Flashcards

1
Q

Osmolarity

A

Amount dissolved in moles/litre

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2
Q

Osmolality

A

Amount dissolved in grams/litre

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3
Q

What happens when [solutes]inside > [solutes]outside?

A
  1. Water moves in which lowers [solutes]inside
  2. [solutes]inside move out which lowers [solutes]inside
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4
Q

Sodium’s and Potassium ions are ….

A

Ubiquitous solutes of the cytosol and extracellular fluid

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5
Q

Na+/ K+ ATPase pump

A

Forms concentration gradients which facilitate a range of cellular functions
- transport of other solutes across the membrane
- propagation of action potential (cell signaling)

Also maintains osmolarity and resting potential

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6
Q

Passive Transport

A
  • No energy required
  • Movement down concentration gradient (channels, symporters, antiporters)
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7
Q

Primary Active Transport

A

Use chemical energy to move substrates against concentration gradient (pumps)

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8
Q

Secondary Active Transport

A

Use the energy contained in a concentration gradient to move solutes uphill (against concentration gradient)

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9
Q

Action Potential

A

The potential difference across the membrane allows for signal transduction via Action Potentials
General idea: change in charge across the membrane opens voltage-gated channels

  1. Stimulus causes depolarization of membrane. This opens voltage gated Na+ channel, allowing Na+ influx. Na+ influx depolarizes membrane.
  2. Voltage-gated K+ channels are slower to open than voltage-gated Na+.K+ exits down concentration gradient, causing repolarization of the cell

3.Depolarisation leads to opening of Voltage gated Ca2+ channels

  1. [Ca2+]i increase triggers release of Ach
  2. ACh binds its receptor (travels across synaptic cleft)

6.Ligand gated channel opens. Na+ and Ca2+ enter through this channel, starting depolarization

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10
Q

Oversupply of Sodium

A

Sodium is oversupplied in the Australian diet
- The SDT (adults) for sodium is 2 000 mg/day
- This is lower than the average intake for Australian adults (~4 000 mg/day)
- Excessive sodium intake can lead to increased risk of:
• Hypertension
• Heart attack
• Stroke

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11
Q

How does Na+ relate to hypertension?

A
  • extracellular (ECF) volume maintains blood pressure
  • blood pressure is important for adequate tissue perfusion
  • changes in salt content of the ECF affect ECF volume
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12
Q

Na+

A
  • The total-body content of Na+ is the main osmotic constituent of ECF
  • Main determinant of ECF volume
  • The total-body content of Na+ is changed through excretion (kidney)
  • Initially, decrease in Na+ will change osmolality
  • To maintain osmolality, H2O will also be lost.
  • If the amount of H2O in the ECF is decreased, the volume of the ECF will decrease, leading to a decrease in blood pressure.
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13
Q

Hyponatremia

A

Low Na+

Caused by:
• excessive sweating
• vomiting
• diarrhoea

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14
Q

Roles of Potassium

A
  • maintaining cellular polarization
  • transport of other solutes
  • maintaining cell volume
  • regulation of intracellular pH
  • regulation of vascular tone
  • control of enzyme function: DNA and protein synthesis, cell growth

Supplied through leafy vegetables, onions, and some spices

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15
Q

There is a limit to how much Na+ the kidney can remove. If the amount of Na+ in the ECF increases, what will happen to blood pressure?

A
  • increase in amount of water in ECF
  • increase in ECF volume
  • increase in blood pressure
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16
Q

Hypokalaemia

A

** Low K+**
- Causes: diuretics, excessive vomiting, diarrhoea
- Effects: Muscle weakness, heart arrhythmia
- Potassium wasting can occur where [Na+]ECF is high:
•Na+ loss achieved by increased glomerular flow rate
• Adversely affects K+ reabsorption in the kidney.

17
Q

Na+/ K+ Balance

A
  • Raised Na+ → decreased K+ reabsorption
  • Need to consume adequate K+
  • K+ has a direct effect on vascular tone:
    Hypokalaemia → exacerbation of the primary hypertension
  • For this reason, the dietary guidelines recommend considering increasing K+ intake when reducing Na+ to treat sodium-sensitive hypertension.
18
Q

3 primary macronutrients

A
  • fat
  • protein
  • carbohydrate
19
Q

Macronutrients provide what?

A
  • energy
  • essential biomolecular components
20
Q

How do protein, fat and carbohydrate affect metabolic health

A
  • quantity of the macronutrient
  • quality of the macronutrient
21
Q

Role of fat

A
  • Some fats are essential
    • linoleic acids
    • α-linolenic acids
  • Fat soluble vitamins are absorbed and transported with fats
  • Metabolism of fat provides energy
  • Fats are necessary for the production of steroid hormones, bile salts, lipoproteins
22
Q

What are some fats “good” and some “bad”?

A

Different types of fat promote the formation of different kinds of cholesterol.

Important: Cholesterol can either refer to
• the family of chemical compounds, or
• the lipoproteins which carry cholesterols and other fats

LDL – low density lipoprotein = “bad” cholesterol. Accumulates, causes atherosclerotic plaques in arteries. Saturated fat contributes to formation of these.

HDL – high density lipoprotein = “good” cholesterol. Can help remove these plaques.
Unsaturated fat contributes to formation of these.

23
Q

Hydrogenated fats

A
  • Unsaturated fats can become rancid – unpalatable
    (chemically: spontaneous conversion to ketones)
  • Can be prevented by converting unsaturated fats to saturated fats
    (hydrogenation – adding hydrogens across double bond)
24
Q

Problem with hydrogenation

A

Some cis double bonds are converted to trans double bonds

25
Q

Trans fats

A

• Increase risk of cardiovascular disease (CVD)
• Increase LDL (“bad”) cholesterol, decrease HDL (“good”) cholesterol
• Increase inflammatory response, further increasing risk of CVD
• Are rare in Australia, but no legal requirement to declare them in nutritional information

26
Q

Essential PUFAs p Omega 3 and 6 fatty acids

A
  • Polyunsaturated Fatty Acids - more than one double bond
  • The double bond closer to the methyl end of the chain is of greater biological importance
  • “Omega” indicates we are counting from the methyl end
  • Omega 3 fatty acids have a double bond between carbons 3 and 4
27
Q

Essential PUFAs - Omega fatty acids

A
  • We cannot synthesise Omega 3 (α-linolenic) and Omega 6 (linoleic) fatty acids, and therefore they must be taken in through the diet.
  • The ratio is important to health:
    • 4:1 or 1:1 is optimal omega 6 FAs : omega 3 FAs
    • The North American settler diet is closer to 30:1
    • Imbalance in this ratio is associated with inflammation, and CVD, and increase in “bad” cholesterol.
  • Omega 3 fatty acids are high in leafy salads and fish oils.
28
Q

Role of protein

A
  • Provides essential amino acids
    • 9 essential, 6 conditionally essential
  • Provides nitrogen for protein synthesis
    • Growth, maintenance, repair
  • Source of energy
  • Very important in growth and development
  • Protein quality is dictated by
    • Amino acid composition
    • Digestibility
  • There is no storage of amino acids
29
Q

Protein metabolism

A
  • Carbon backbone is used to produce energy
  • Glucogenic → pyruvate or TCA cycle intermediates
  • Ketogenic → acetoacetate or acetyl CoA
  • Some AA - both categories
30
Q

Carbohydrates

A
  • Primary source of energy for most people
  • Types of carbohydrates
    • Fibres
    • Starches
    • Sugars
  • Carbohydrate metabolism
    • Glycolysis
    • Pentose Phosphate Pathway
    • Glycogenesis / Glycogenolysis (storage)
    • FA synthesis (storage)
31
Q

Assessing carbohydrate quality

A
  • Glycaemic index
  • High GI food causes rapid rise in blood glucose
  • Low GI food causes gradual, lower rise in blood glucose
32
Q

Whole and refined carbohydrates

A

Whole grains contain fibre
• Can be milled (remove endosperm, germ, bran), as long as product contains those elements

Refined
• Only the starch component

33
Q

Dietary Fibre

A
  • Non-digestible forms of carbohydrates, and lignin.
  • Increases satiety
  • Protects against cardiovascular disease, obesity, type 2 diabetes
  • Essential for digestive health: colonic lubrication and transit
  • Provided in the diet by whole grain foods, cooked dry beans and peas, vegetables, fruit and nuts
34
Q

Added Sugars

A
  • Dietary guidelines state to reduce intake of added sugar
  • Added sugar has no additional nutrients, and overconsumption can eventually lead to type 2 diabetes
  • Added sugar consumption occurs almost exclusively through consumption of sweetened beverages, and in snack foods

Health And Society (7 decks)

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