Ingredients of Life

Question 1

What is hypokalemia?

Answer 1

Low plasma potassium ion level
Hypo: below normal

Question 2

Physical examination of hypokalemia

Answer 2

Dry tongue and mucous membrane (possible dehydration)

Acute onset of muscle weakness (generalized, more prominent in the lower limb)

Question 3

Composition of blood

Answer 3

Formed elements (cell and cell fragments) suspended in plasma, which is mostly water

Plasma
- 55-60% of blood volume (can flucuate from time to time due to dehydration and overhydration)

Formed elements (40-45% of blood volume)
- Erythrocytes (red blood cells): 99%
- Leukocytes (white blood cells): < 1%
- Platelets: < 1%

Question 4

Spin down whole blood using a centrifuge

Answer 4

• Plasma
• Buffy coat: leucocytes and platelets
• Packed cells and solids: erythrocytes (red blood cells)

Question 5

Composition of plasma

Answer 5

Water, proteins, nutrients, metabolic wastes, hormones and inorganic electrolytes (K+ and Na+ ions)

Question 6

Hematocrit

Answer 6

Percentage of blood volume that is red blood cells

Question 7

Average size adult

Answer 7

70kg

Question 8

Serum

Answer 8

• Clearer than plasma
• Can be obtained by setting the blood sample at room temperature for 30 mins before centrifuging it
• This is because the blood clotted and the fibrinogen and other clotting proteins are removed

Question 9

Important electrolyte

Answer 9

Nerve impulse (action potential): Ca2+, K+, Na+
Major extracellular anion: Cl-
Major intracellular cation: K+
Major extracellular cation: Na+
Acid and base balance: H+

Question 10

0.9% sodium chloride (NaCl)

Answer 10

• Normal saline
• Sterile: X micro-organism
• Non-pyrogenic: X fever-causing substances
• for fluid and electrolyte replenishment
• isotonic volume expander (increase blood volume) and electrolyte replacement for intravenous infusion (dip)

Question 11

Hypernatremia

Answer 11

Plasma Na+ ion level is higher than normal in the plasma

Ions (Na+ and Cl-) attract and retain water, Na+ affects water balance (i.e. blood volume), then indirectly affects blood pressure called mean arterial pressure (MAP), may trigger stroke

Question 12

Isomers

e.g. glucose, fructose, and galactose

Answer 12

In ileum, fructose and galactose are subsequently converted into glucose as only glucose can be digested and used as a source of energy

Question 13

Normal physiological concentrations of important ions in plasma

Key to their ability to produce physiological functions

Answer 13

Na+ ion: 135-145 mmol/L
K+ ion: 3.5-5.0 mmol/L

Question 14

Water

Answer 14

• Most abundant substance in human body (60% of total body weight)
• Provides an optimal medium in which cells can function
• Major transport component of the body
• Aids in thermoregulation
• Provides cushioning
• Acts as lubricant
• Breaks down food particles into smaller components in the digestive system
• I srequired for a variety of metabollic processes that are necessary for survival
• Is a good physiological solvent for electrolytes and non-electrolytes

Question 15

Surface tension

Answer 15

Cohesion: forces of attraction between like molecules
Adhesion: forces of attraction between dissimilar molecules

Both of them lead to the formation of meniscus (bending of the liquid surface)

Question 16

Meniscus

Answer 16

Water forms bowl-shaped (concave) meniscus: adhesive forces > cohesive forces
* measure the center bottom

Mercury forms dome-shaped (convex) meniscus: cohesive forces > adhesive forces
* measure the center top

Question 17

Manometers

to measure the pressure by means of a vertical coumn of fluid

Answer 17

Mercury sphygmomanometer: measurement of arterial blood pressure

Saline manometer: measurement of central venous pressure (CVP)

Question 18

Lack of surfactants in the lungs

Answer 18

Insufficient surfactant leads to reduced pulmonary compliance and increased surface tension. This increases risk of alveoli collapse at end-expiration followed by reduction in total surface area for gaseous exchange. Lung may undergo collapse and cause the patient to have difficulty breathing.

Question 19

Pulmonary surfactant

Answer 19

Acts as a film to keep alveoli open by reducing the cohesive forces between water molecules

• Lubricates the alveoli and allow them to expand without overstretching and get smaller without collapsing
• Produced by type II alveolar cells

Question 20

Newborn Respiratory Distress Syndrome (NRDS)

Answer 20

• Life-threatening breathing disorder of premature newborns which commences at or soon after birth (mostly before 28th week)
• Surfactants are normally produced between 34th and 36th wee of pregnancy
• Management: breathing support and artificial surfactant

Question 21

Organic molecules

Answer 21

• Accounts for 18% of body weight

Question 22

Dehydration (Condensation)

Answer 22

Removes the equivalent of a water molecule to link molecular units so that macromolecules can be built

Question 23

Hydrolysis

Answer 23

Adds the equivalent of a water molecule to break apart macromolecules

Question 24

Carbohydrates

Answer 24

The most abundant monosaccharide in human: glucose, stored in cells in the form of polysaccharide glycogen

Oligosaccharide
* Sucrose: glucose + fructose
* Maltose: glucose + glucose
* Lactose: glucose + galactose

Question 25

Proteins

Answer 25

Haemoglobin (found in rbc): contains heme (Fe) pigment, carries oxygen in blood
Myoglobin: contains heme pigment, store oxygen in striated muscles (skeletal and cardiac muscles)

Question 26

4 levels of structure of protein

Answer 26

Primary
* Chain of amino acids
* Alightest change of sequence affects the protein’s ability to function

Secondary
* Coiling (alpha helix) and folding (pleated sheet) of polypeptide are resulted from hydrogen bonding

Tertiary (Polypeptide, a single subunit of transthyretin/thyroxine)
* Three dimensional shape
* Results from interactions between the R groups of various amino acids
* Disulphide bridges (between two sulphur molecules) are covalent bonds that further strengthen the protein’s shape
* Hydrophobic interactions between two non-polar side chains

Quaternary (thyroxine)
* Two or more polypeptide chains associated together

Question 27

Gobular protein

Answer 27

• Ball-shaped
• Functional protein
• E.g. enzymes, plasma proteins (low level of albumin caused swelling), erythrocyte pigment haemoglobin

Question 28

Fibrous protein

Answer 28

• Rope-like
• Structural protein
• E.g. keratin (provides impermeability on the epidermis), collagen (toughness of the skin), elastin (elasticity of the skin), fibrinogen (protein precursor of fibrin)