IB Biology Option D

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