Metabolism Flashcards
Moderate physical activity daily expenditure of a 58 kg adult female
9500kJ
Moderate physical activity daily expenditure of a 70kg adult male
12000kJ
Components of daily expenditure
Basal Metabolic Rate
Voluntary physical exercise
Diet-induced thermogenesis
Use of fats
Absorb fat-soluble vitamins
Energy source after carbohydrates
Examples of essential fatty acids
Linoleic acids
Linolenic acids
What are essential fatty acids used for?
Structural component of cells membranes
Precursors of important regulatory molecules (eicosanoids)
Use of proteins
Amino acids, product of digestion of protein
Used in synthesis of essential N-containing compounds
E.g. Creatine, nucleotides, haem
Excretion of proteins
Degraded and excreted in urine as urea
What are essential amino acids?
Cannot be synthesised in body
Come from dietary protein
Why are carbohydrates essential to diet?
Major energy-containing component of diet
17kJ/g
How much of the adult body weight is water?
50-60%
Fibre essential to diet?
Non-digestible plant material for normal bowel function
E.g. Cellulose
Minerals and vitamins in diet
Either water-soluble or lipid-soluble
Deficiency disease associated with the absence/excess of these
Clinical signs of starvation
Cold and weakness
-> loss of subcutaneous fat and muscle wasting
Infections of GI tract and lungs are common
Cause of marasmus
Protein-energy malnutrition
Common in children under 5
Cause of kwashiorkor
Young child displaced from breastfeeding
Fed diet with some carbohydrate but very low protein content
Clinical signs of marasmus
Emaciated look Obvious signs of muscle wasting and loss of body fat (no Oedema signs) Hair is thin and dry Diarrhoea common Anaemia may be present
Clinical signs of kwashiorkor
Apathetic Lethargic Anorexic (loss of apetite) Distended abdomen Oedema Anaemia is common
Why do kwashiorkor sufferers have a distended abdomen?
Hepatomegaly
Ascites
What is a hepatomegaly?
Enlarged liver
What is ascites?
Accumulation of fluid in the peritoneal cavity
How does generalised oedema occur in kwashiorkor?
Due to low serum albumin (osmotic pressure)
Calculate BMI
Height^2 (m^2)
Underweight BMI
<18.5
Desirable BMI
18.5-24.9
Overweight BMI
25-29.9
Obese BMI
30-34.9
Severely obese BMI
> 35
Define obesity
Excess body fat has accumulated to the extent that it may have an adverse effect on health
BMI greater than 30
Leading to reduced life expectancy/ increased health problems
Define homeostasis
Maintenance of a stable internal environment
Dynamic equilibrium
Homeostatic mechanisms act to counteract changes in the internal environment
What are the two main communication pathways?
Nervous system Endocrine system (hormones)
What is paracrine control?
Local release (via ducts/ exocrine) and action
What is autocrine control?
Agents released by a cell which affects the releasing cell
Branches of peripheral nervous system
Afferent branch (sensory input) Efferent branch (motor output)
What does the control centre do?
Establishes the reference set point
Analyses the afferent input
Determines the appropriate response
Examples of control centres in the brain
Hypothalamus in diencephalon
Medulla oblongata in brain stem
Role of hypothalamus
Control of endocrine system
Role of medulla oblongata
Control of ventilation and the cardiovascular system
Role of receptors
Detect stimuli
E.g. Changes in internal environment
Specialised nerve endings
E.g. Chemo/thermoreceptors
Sensors from receptors to control centre
Communicate input via afferent nerves
Role of effector
Causes change
Control centre produces an output
Communicated via efferent pathways to effectors
E.g. Sweat glands activated to produce more sweat causing heat loss
Biological rhythm of cortisol
Peak at 7am to 7pm
Circadian rhythm
Low blood cortisol
Hypo activity of adrenal cortex
Addisons’s disease
High blood cortisol
Hyperactivity of adrenal cortex
Cushing’s syndrome
Marker for ovulation
Sudden increase in core body temperature
Define cell metabolism
Highly integrated network of chemical reactions that occur within cells
Cells metabolise nutrients to provide
Energy for cell function (and synthesis of cell components (ATP))
Building block molecules (synthesis of cell components for growth, maintenance, repair, division of cell)
Organic precursor molecules (eg acetyl CoA, intercom version of building block molecules)
Biosynthetic reducing power (used in the synthesis of cell components NADPH)
Cell nutrients in blood comes from
Diet
Synthesis in body tissues from precursors
Released from storage in body tissue
What happens to cell nutrients?
Degradation to release energy in all tissues
Synthesis of cell components in all tissues except RBC
Storage in liver, adipose tissue, skeletal muscle
Define catabolism
Breakdown of larger molecules into smaller ones
Define anabolism
Smaller molecules built up into larger ones
Catabolic pathways
Large -> small
Oxidative - release H+ (reducing power)
Release large amounts of free energy (some conserved as ATP)
Produces intermediary metabolites
Anabolic pathways
Small -> large
Reductive - use H+ ions
Use intermediary metabolites and energy (ATP) produced by catabolism to drive the synthesis of important cell components
What is exergonic?
Energy releasing (Gibbs Free Energy -ve)
Energy release from phosphorylated compounds
Have high energy of hydrolysis
Phosphate phosphate bond is high energy bond
Creating phosphate in muscle
Muscle needs to increase metabolic activity very quickly
Need a reserve of high energy stores that can be used immediately
Reaction catalysed by creatine kinase in muscle
Creatine + ATP Creatine Phosphate + ADP
High ATP forward reaction is favoured
What happens in oxidative reactions?
Electrons are removed
Removal of hydrogen atoms
