Biology - Option D > Option D > Flashcards

Option D Flashcards

(48 cards)

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1
Q

What are nutrients?

A

Chemical substances in foods that are used in the (human) body

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2
Q

What are essential nutrients?

A
  • Cannot be synthesised by the body
  • Must be taken in by diet
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3
Q

What can be used for energy?

A

(In aerobic cell respiration)
- Carbohydrates
- Lipids
- Amino acids
(If energy in diet is insufficient)
- Glycogen + fat reserves

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4
Q

Measuring energy content (equation)

A

temp rise (c) x water volume (ml) x 4.2J
/ mass of food (g)

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5
Q

Measuring energy content (other)

A

Burning the food in a food calorimeter which traps heat from combustion (more efficiently)

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6
Q

What is there a correlation between for CHD?

A

High levels of cholesterol (in blood plasma) and an increased risk of CHD

Note: lowering cholesterol may not reduce risk of CHD

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7
Q

Vitamin D Deficiency (consequences)

A
  • Not enough calcium is absorbed from food (in the gut)
  • Same as calcium deficiency symptoms (eg. Osteomalacia)
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8
Q

What is osteomalacia and its consequences?

A
  • Inadequate bone mineralisation (due to calcium salts not being deposited or reabsorbed)
  • Bones become softened

Note: In children, it’s called rickets

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9
Q

How is vitamin D synthesised and stored?

A
  • Contained in oily fish, eggs, milk, butter, cheese, and liver
  • Can be synthesised in the skin (by UV light)
  • Liver can store vitamin D in liver (for winter)
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10
Q

How is cholera caused?

A
  • (Disease) Caused by infection of the gut w/ the bacterium ‘Vibrio cholerae)
  • Releases toxin which binds to receptor on intestinal cells -> brought into cell (endocytosis)
  • When in cell: triggers release of Cl- and HCO3- ions (from cell into intestine)
  • Water leaves cell by osmosis (leads to watery diarrhoea)
  • Water taken from blood into cells to replace the lost fluid (leads to dehydration)
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11
Q

Vitamin C deficiency (in mammals)

A

AKA ascorbic acid
- Needed for the synthesis of collagen fibres (in many body tissues + blood vessel walls)
- Scurvy = deficiency of vitamin C
- Essential nutrients for humans

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12
Q

How is stomach acid secreted?

A

Proton pump (H+/K+ ATPase) in parietal cells in stomach epithelium

  • Pumps exchange protons from cytoplasm with potassium ions from the stomach
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13
Q

How is tyrosine synthesised?

A

Phenylalanine –(phenylalanine hydroxylase)—-> tyrosine

  • Phenylalanine is an essential nutrient
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14
Q

What is phenylketonuria (PKU)?

A

Disease caused by too much phenylalanine in blood (due to lack of phenylalanine hydroxylase)
- Caused by mutation of gene coding for the enzyme
- Recessive allele

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15
Q

what are the consequences and treatment of PKU?

A
  • Diet with low levels of phenylalanine (Eat small amounts of meat, fish, nuts, cheese, and beans) AND (maybe) tyrosine supplements
  • Causes reduction in head + brain growth in newborns
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16
Q

What causes stomach ulcers?

A

Partial digestion of the stomach lining by the enzyme pepsin + hydrochloric acid (in gastric juice)

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17
Q

How are digestive juices secreted?

A

Exocrine gland: secrete through duct onto surface of the body or into the lumen of the gut
Endocrine gland: ductless, sectete hormones directly into the blood

  • Only exocrine glands secrete digestive juices
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18
Q

What does gastric juice do?

A
  • Secreted by cells in epithelium that lines the stomach
  • Hydrogen ions are secreted by the parietal cells -> makes contents of stomach acidic
  • Helps w/pathogen control + assist w/some hydrolysis reactions
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19
Q

How is the secretion of gastric juice controlled?

A
  • By nerves AND hormones
    Nervous mechanism:
    1. Sight + smell of food triggers response by which gastric juice is secreted by the stomach
    2. When food enters stomach -> distension (detected by stretch receptors)
    3. Signals sent to brain to release digestive hormones

Hormonal mechanism:
1. Gastrin is secreted into bloodstream + stimulates release of stomach acids
2. If stomach pH is too low (becomes acidic) gastrin secretion is inhibited
3. When digested food passes into small intestine, digestive hormones are released

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20
Q

What are the functions of the liver?

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A

Detoxification: hepatocytes absorb toxic substances from blood + convert them by chemical reactions into non-toxic or less toxic substances

Breakdown of erythrocytes: kupffer cells in the walls of sinusoids absorb + break down damaged red blood cells + recycle them

Cholesterol to bile salts: converted by hepatocytes

Production of plasma proteins: rough ER (of hepatocytes) produce 90% of proteins in blood plasma

Nutrient storage + regulation

21
Q

How does blood flow through the liver?

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A

Hepatic portal vein = deoxygenated (already flowed through stomach/intestine walls)

Hepatic portal vein - divides into sinusoids

Hepatic artery = oxygenated blood (from aorta)

Hepatic artery - branches into capillaries (join sinusoids)

22
Q

What are the features/structures of sinusoids?

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A
  • Wider than normal capillaries
  • Wall = single layer of thin cells
  • Pores + gaps between cells = allow blood flow in sinusoids to be in close contact to hepatocytes
23
Q

What is juandice?

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A
  • Skin and eyes become yellow
  • Caused by accumulation of bilirubin in blood plasma
  • Caused by things such as hepatitis, liver cancer, and gallstones
  • In infants: can cause brain damge that leads to deafness + cerebralpalsy
    -In adults: itchiness
24
Q

What is the role of lipoproteins?

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A
  • Transports cholesterol
  • Low density lipoproteins (LDL) = bad – carries cholesterol from liver to body tissue
  • High density lipproteins (HDL) = good – collects cholesterol from body tissue + takes to liver for removal from the blood
25
What are the functions + features of cardiac muscle?
- Junctions between cardiac muscle cells = intercalated discs - Junctions have cytoplasmic connections between cells -- allow for the movement of ions -> rapid conduction of electrical signals
26
How is blood pressure measured?
1. Cuff placed around the upper arm + inflated to constrict the arm + prevent blood in the arteries from entering the forearm 2. Cuff slowly deflated + doctor listens with stethoscope for sounds of blood flow in the artery 3. Sound occurs when cuff pressure drops below the systolic pressure 4. Cuff further deflated until no more sounds -- happens when cuff pressure drops below diastolic pressure
27
Blood pressure levels
High blood pressure (hypertension) = 140 systolic over 90 diastolic (+ above) Pre high blood pressure = 120 - 140 systolic over 80 - 90 diastolic Ideal blood pressure = 90 - 120 systolic over 60 - 80 diastolic Low blood pressure = 70 - 90 systolic over 40 -60 diastolic
28
What are the risk factors for hypertension?
- Obesity - Exercise - Too much salt in diet - Too much coffee/alcohol - Genetic factors
29
What are the consequences of hypertension?
- Heart attack - Stroke - Damage to wall of arteries
30
What are the risk factors for thrombosis?
(thrombosis = blood clots inside blood vessels) - high HDL lvls in blood - high lvls of saturated fats + trans fats in diet - inactivity (eg. sitting on plane) - smoking - hypertension - genetic factors
31
What are the consequences of thrombosis?
- Heart attack (if in coronary arteries) - Stroke (if in carotid arteries)
32
What is coronary heart disease (CHD)?
Damage to heart due to blockages or interruptions to the supply of blood in coronary arteries
33
What do artificial pacemakers do?
Regulates heart rate + ensures that it follows a steady rhythm - Provide a regular impulse OR - Only when a heartbeat is missed
34
What do defibrillators do?
1. Device detects whether the ventricles are fibrillating 2. If they are: delivers an electrical discharge (often stops the fibrillation) Note: fibrillation = twitching of the ventricles due to rapid + chaotic contraction of individual muscle cells
35
What part of the brain is responsible for appetite?
Hypothalamus
36
What are exocrine glands?
- Secrete to the surface of the body (eg. sweat) or the lumen of the gut (digestive) - Produce + secrete via a duct onto an epithelial surface Examples: Salivary glands Gastric glands Pancreatic glands Intestinal glands
37
What are exocrine glands made of?
- A clustor of secretory cells which collectively form an acinus - Surrounded by a basement membrane + held together by junctions between secretory cells - Secretory cells = rich in mitochondria Exocrine gland -> duct -> epithelial surface
38
What are the features of villi?
Microvilli: increases SA:V Rich blood supply Single layer epithelium: minimises diffusion distance between lumen + blood Lacteals: absorb lipids from intestine Intestinal glands: exocrine pits release digestive juices Membrane proteins: facilitates transport of digested materials into epithelial cells
39
What are endocrine glands?
- Comprised of ductless glands - Release chemicals into the blood to regulate body functions - Secrete hormones - Slower but longer reponse compared to nervous system
40
What are pituitary glands?
- Lies adjacent to hypothalamus + in direct contact due to a portal blood system - Receives instructions from the hypothalamus Responsible for: Metabolism Adult development Reproduction Growth Equilibrium/Homeostasis
41
What is the growth hormone (somatotrophin)?
- Acts directly to reduce the formation of adipose cells - Acts indirectly via insulin growth factor to increase muscle mass + bone size
42
How is CO2 transported?
Three ways: 1. bound to haemoglobin (binds to globin, rather than haem - oxygen) 2. dissolved in water + carried (only about 5%, CO2 doesnt dissolve well in H2O) 3. diffuses into the erythrocyte + gets converted into carbonic acid (75%)
42
What are alveoli (alveokus) made up of?
Lined by pneumocytes, surrounded by capilliaries (on outside) Type I pneumocytes = very thin, mediate gas exchange with bloodstream Type II = pneumocytes secrete pulmonary surfactant to reduce the surface tension within the alveoli
43
How is carbonic acid transported?
1. When CO2 enters erythrocyte it combines with water to form carbonic acid 2. Dissociated to form hydrogen ions + bicarbonate 3. Bicarbonate pumped out of cell 4. Bicarbonate in plood plasms combines with sodium + travels to the lungs 5. Hydrogen ions (in erythrocyte) make environment less alkaline - haemoglobin releases oxygen 6. When red blood cell reaches lungs, bicarbonate is pumped back into the cell + process is reversed
44
What is a hormone used in appetite control?
Leptin - secreted by adipose tissue, depresses appetite
45
What causes stomach ulcers?
H. pylori - secretes a protease - breaks down lining
46
What is osmolarity?
No. of particles of solute per litre of solution
47
What does the large intestine do?
Reabosrbs water and mineral ions Egests materials that aren't absorbed
Biology - Option D
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