Studied by 4 people
Minerals
specific elements such as calcium and iron
vitamins
chemically diverse carbon compounds needed in small amounts that cannot be synthesized by the body
example of fatty acids that, along with some amino acids allow the production of proteins at ribosomes to continue
omega-3 fatty acids
malnutrition
deficiency, imbalance or excess of specific nutrients in the diet
what can carbohydrates, lipids and amino acids all be used for as a source of energy
aerobic cell respiration
what happens when the energy in the diet is insufficient
reserves of glycogen and fats are mobilised and used.
starvation
prolonged shortage of food
what happens when glycogen and fat reserves are used up
body tissues have to be broken down and used in respiration (starvation & anorexia)
Anorexia
an individual does not eat enough food to sustain the body even though it is available
what can happen in advanced cases of anorexia
heart muscle is broken down
obesity
excessive storage of fat in adipose tissue, due to prolonged in take of more energy in the diet than is used in cell respiration
obesity can lead to which health issues
hypertension (high blood pressure) and Type 2 diabetes
what is responsible for feelings of appetite or satiety
hypothalamus
energy content of a food=
(temp rise X water volume (ml) X 4.2L)/mass of food (g)
what are considered more important than dietary intake when talking about heart disease
genetic factors, some families have high cholesterol even with low dietary intake
what happens when there is insufficient vitamin D in the body
calcium is not absorbed from food in the gut to large enough quantities
osteomalacia
inadequate bone mineralization due to calcium salts not being deposited or being reabsorbed so bones become softened
osteomalacia in children
rickets
what is unusual about vitamin D
can be synthesised in the skin but only by UV light
what is ascorbic acid needed for
synthesis of collagen fibres in many body tissues including skin and blood vessel walls
lack of vitamin c causes
scurvy
why were attempts to induce scurvy in rats unsuccessful
most mammals (apart from humans) have enzymes needed for synthesis in ascorbic acid
what happens in phenylketonuria
level of phenylalanine in the blood becomes too high
cause of phenylketonuria
insufficiency or complete lack of phenylalanine hydroxylase due to a mutation of the gene coding for the enzyme
what type of disease is PKU
genetic disease and the allele is recessive
what protects the stomach lining
natural mucus barrier
what are stomach ulcers
open sores, caused by partial digestion of the stomach lining by the enzyme pepsin and hydrochloric acid in gastric juice
80% of ulcers due to
infection with the bacterium Helicobacter pylori
where is gastric juice secreted
cells in the epithelium that lines the stomach
what is the acidity of the stomach and what does it help with
1-3pH which helps to control pathogens in ingested food that could cause food poisoning
what is liver composed of
hepatocytes
detoxification
hepatocytes absorb toxic substances from the blood and convert them by chemical reactions in to non-toxic or less toxic substances
life span of erythrocytes (red blood cells)
120 days
kupffer cells
in the walls of sinusoids in the liver are specialised macrophages that absorb and break down damaged red blood cells by phagocytosis and recycle their components
hepatocytes conver cholesterol in to
bile salts which are part if the bile that is produced in the liver
what happens when the bile is secreted in to the small intestine
the bile salts emulsify droplets of lipid, greatly speeding up lipid digestion by lipase
cholesterol is transported in
lipoproteins
how is high density lipoprotein a 'good cholesterol'
collects cholesterol from body tissues and carries it back to the liver for removal from the blood
how many vessels supply the liver with blood and what are they
2- hepatic portal vein and hepatic artery
sinusoids
inside the liver the hepatic portal vein divides in to vessels
which side of the heart is blood from the liver carried to
carried by the hepatic vein to the right side of the heart via the inferior vena cava
what is jaundice
condition in which the skin and eyes become yellow due to an accumulation of bilirubin in blood plasma
results of jaundice
infants: brain damage resulting in deafness and cerebral palsy adult: itching
junctions between cardiac muscle cells called
intercalated discs
what are also visible in electron micrograph of cardiac muscle
sarcomeres and mitochondria
what stimulates contraction
intercalated discs between adjacent cardiac muscle cells allow impulse to spread through the wall of the heart stimulating contraction
where is the sinoatrial node found and what does it do
small region in the wall of the right atrium, initiates each impulse and so acts as the pacemaker of the heart
0.09 seconds delay allows
atria time to pump blood in to ventricles before they contract
conducting fibres
impulses are sent from the AV node along them
"lub" sound of heartbeat
closure of the atrioventricular valves
dub sound of heart
closure of semilunar valves
electrocardiogram
detect electrical signals from the heart
artificial pacemakers
medical devices that are surgically fitted in patients with a malfunctioning sinoatrial node or a block in the signal conduction pathway within in the heart.
what do artificial pacemakers consist of
pulse generator and battery placed under the skin below the collar bone with wires threaded through veins to deliver electrical stimuli to right ventricle
risk factors causing hypertension
obesity, not doing exercise, too much salt, drinking large amounts of coffee and alcohol and genetic factors
hypertension can lead to
damaged kidneys, stroke, heart attack
thrombosis
formation of blood clots inside blood vessels
risk factors leading to thrombosis
high density lipoprotein, high levels of saturated fats and trans fats in the diet, inactivity for example on aeroplanes, smoking, hypertension, genetic factors
ventricular fibrillation
twitching of the ventricles due to rapid and chaotic contraction of individual muscle cells
