Metabolism S1 - Nutrition, Diet, Homeostasis and Energy reactions in cells

Question 1

What are the features of catabolic pathways in metabolism?

Answer 1

Break down of molecules (large to small)

Releases energy (some conserved as ATP)

Produces reducing power (release of H+)

Produces intermediary metabolites

Question 2

What are the features of anabolic pathways in metabolism?

Answer 2

Builds smaller molecules into larger ones

Reductive (uses H+ ions)

Uses intermediary metabolites and energy as ATP to synthesise new cell components

Question 3

What is the daily energy expenditure of a 70kg male?

Answer 3

12,000kJ

Question 4

What is the daily energy expenditure of a 58kg woman?

Answer 4

9,500kJ

Question 5

Daily energy expenditure is comprised of what 3 basic components?

Answer 5

Energy to support base metabolism (basal metabolic rate)

Energy for voluntary physical exercise

Energy to process food we eat (diet induced thermogenesis)

Question 6

List the essential components of the diet

Answer 6

Fats

Carbohydrates

Proteins

Water

Fibre

Minerals and vitamins

Question 7

Why are fats essential to diet?

Answer 7

Necessary to absorb fat soluble vitamins (ADEK)

Contain essential fatty acids (eg linoleic and linolenic acids)

Question 8

What is the energy yield of fats compared to carbohydrates?

Answer 8

2.2 times greater

Question 9

What are the fatty acids linolenic acid and linoleic acid used for?

Answer 9

Structural components of cell membrane

Precursors of important regulatory molecules (eicosanoids)

Question 10

Why are proteins essential components of the diet?

Answer 10

Amino acids used in synthesis of N containing compounds (eg. Creatine, nucleotides, haem)

Maintain nitrogen balance

Contain essential amino acids that can’t be synthesised by the body.

Question 11

What is the nitrogen balance?

Answer 11

Intake of N2 = N2 loss daily

Question 12

How much protein is degraded and excreted per day and hence what is the daily protein requirement in the diet?

Answer 12

Average 35g degrades

35g intake required to maintain nitrogen balance

Question 13

Why are carbohydrates and essential dietary requirement?

Answer 13

Main source of energy in diet

Question 14

What is the energy content of carbohydrates per gram?

Answer 14

17kJ/g

Question 15

Are fats necessary for energy production?

Answer 15

Nope

Question 16

Why is water an essential dietary component?

Answer 16

Water lost by the body each day, must be replaced by drinking

Question 17

What proportion of the body weight is water?

Answer 17

50-60% adult

70% child

~50% elderly/obese

Question 18

How much water is lost to the body a day and how is it lost?

Answer 18

2. 5L lost total
3. 5L urine
4. 4L expired air
5. 5L skin/sweat
6. 1L Faeces

Question 19

How is water gained by the body?

Answer 19

Drinking

Cellular metabolism (0.35L)

Question 20

Why is fibre necessary in the diet?

Answer 20

Normal bowel function

Question 21

Why are minerals and vitamins necessary in the diet?

Answer 21

Deficiency/absence/excess of these associated with disease.

Question 22

In adults what can starvation lead to?

Answer 22

Muscle and subcutaneous fat wasting as fat and protein reserves used for energy.

Question 23

What are the common complaints of starvation?

Answer 23

Cold, muscle weakness, GI tract and lung infections common

Question 24

What is marasmus?

Answer 24

Protein-energy deficiency most commonly seen in children under 5

Question 25

What are symptoms of marasmus?

Answer 25

Emaciated appearance (muscle and fat wasting) Hair is thin/dry Diarrhoea/anemia commonly present NO oedema

Question 26

What is kwashiorkor?

Answer 26

Form of malnutrition typically found in young children that stop breast feeding to early and are fed a low protein diet with some carbohydrate.

Question 27

What are the common complaints in a child with kwashiorkor?

Answer 27

Apathy Lethargy Anorexia Distended abdomen Generalised oedema Anaemia common

Question 28

Why is the abdomen distended and generalised oedema seen in children with kwashiorkor?

Answer 28

Distended abdomen due to hepatomegaly (enlarged liver) and/or ascites (fluid in peritoneal cavity) Generalised oedema due to low serum albumin (low blood osmotic pressure)

Question 29

How is BMI calculated?

Answer 29

Weight (kg) / (height (m) squared)

Question 30

How is BMI interpreted?

Answer 30

Underweight = \<18.5 Desirable range = 18.5 - 24.9 Overweight = 25 - 29.9 Obese = 30 - 34.9 Severely obese = \>35

Question 31

Define obesity

Answer 31

Excess body fat accumulation that may have adverse effect on health leading to reduced life expectancy and/or increased health problems

Question 32

What leads to changes in body weight?

Answer 32

Differences between input of substances and output of substances and energy will lead to increase or decrease in body weight

Question 33

Define homeostasis then explain its importance and what it controls.

Answer 33

The maintenance of a stable internal environment. A dynamic equilibrium that acts to counteract changes in the internal environment Occurs at all levels from cellular to organ/system to whole body Controls supply of nutrients, oxygen, blood flow, temperature, removal of waste and pH Failure of homeostasis leads to disease

Question 34

What are the 2 major communication pathways of the body?

Answer 34

Nervous and endocrine

Question 35

What is paracrine control?

Answer 35

Local release of hormones (via ducts/exocrine)

Question 36

What is autocrine control?

Answer 36

Release of agent which affects the releasing cell.

Question 37

What two categories can the peripheral nervous system be sorted into?

Answer 37

Efferent - motor output Afferent - sensory input

Question 38

What are the major features of the bodies control system?

Answer 38

Communication Control centre Receptor Effector

Question 39

What are the functions of the control centre of the body's control system

Answer 39

Establishes reference set points Analyses afferent input and determines response

Question 40

Where is the hypothalamus and what does it control?

Answer 40

Found in the diencephalon Involved in control of the endocrine system

Question 41

Where is the medulla oblongata and what functions is it involved in?

Answer 41

Found in brainstem Involved in control of ventilation and cardiovascular system.

Question 42

What are receptors in the PNS of the body involved in?

Answer 42

Detect stimuli with specialised nerve endings and communicate this to the CNS via afferent nerves

Question 43

What is the function of effectors?

Answer 43

Cause change when prompted by efferent nerve stimulation

Question 44

Are set points of control by the CNS fixed? Give an example of set point control

Answer 44

No, they can vary over time Eg. Cortisol peaks around 7am and troughs around 7pm this is known a circadian rhythm.

Question 45

The menstrual cycle is a good example of what?

Answer 45

A biological rhythm, a woman's core body temperature varies throughout the cycle. (Sharp increase indicates ovulation).

Question 46

Define cell metabolism

Answer 46

Highly integrated network do chemical reactions comprised of a series of metabolic pathways (some specific to specialised cells, some general).

Question 47

What are the functions of cell metabolism?

Answer 47

Metabolise nutrients to produce a variety of products.

Question 48

What is produced by cell metabolism and what are the products used for?

Answer 48

Energy for cell function - produces ATP Building block molecules - used in the synthesis of cell components needed for growth, repair and division of the cell Organic precursor molecules - used to interconvert building block molecules (eg. AcetylCoA) Biosynthetic reducing power - used in the synthesis of cell components (eg NADPH)

Question 49

Where do cell nutrients in the blood come from?

Answer 49

Diet Synthesis in other tissues Release from storage in other tissues

Question 50

What are cell nutrients used for?

Answer 50

Degradation for energy release Synthesis of cell components Storage - (only in liver, adipose tissue, skeletal muscle)

Question 51

Why do cells need a continuous supply of energy?

Answer 51

To maintain function

Question 52

Explain the concept of energy coupling and how it's performed.

Answer 52

Transferring energy released in exergonic reactions to endergonic reactions. This is performed by intermediary molecules of the ADP/ATP cycle.

Question 53

Name three high energy phosphorylated compounds and give the energy released by their hydrolysis

Answer 53

Phosphoenolpyruvate = -62kJ.mol-1 Creatine phosphate = -43kJ.mol-1 ATP = -31kJ.mol-1

Question 54

What is the equation for hydrolysis of ATP or ADP ans how much energy is released?

Answer 54

ATP + H2O \<--\> ADP + Pi ADP + H2O --\> AMP + Pi Releases -31kJ.mol-1

Question 55

What is Creatine phosphate used for?

Answer 55

To provide a store of high energy molecules that can be used immediately for metabolism in high activity tissues eg. muscle

Question 56

What is the reaction for the phosphorylation of Creatine, what enzyme is involved and how is it controlled?

Answer 56

Creatine + ATP \<--\> Creatine phosphate + ADP When ATP is high forward reaction favoured Catalysed by Creatine kinase

Question 57

How is ATP involved in regulation of metabolism?

Answer 57

High ATP concentration leads to activation of anabolic pathways Low ATP concentration leads to activation of catabolic pathways

Question 58

What signals a cell has adequate energy?

Answer 58

High levels of ATP as well as reducing agents such as FADH/NADHH/NADPH are high energy signals

Question 59

What signals a cell has low energy?

Answer 59

High levels of ADP and NAD+/FAD/NADPH+

Question 60

Carrier molecules such as NAD+ are derived from what type of molecule?

Answer 60

B vitamins

Question 61

What can be said about the total amount of H+ carrier molecules in the body?

Answer 61

Total amount is constant