Top 10 Tricky Science Questions: Biology
Top Ten Questions
I try to teach my pupils that science is not so much about getting answers, but about asking questions. This hub comprises 10 of the best biology questions I have been asked by my students during their biology lessons in the past year. We shall investigate some of the pressing questions of our age:
- What IS brain-freeze?
- Why DO we get spots?
- WHY do we get dizzy?
As time goes on, each topic will gain a link to a hub that expands on the topic in much greater depth. So sit back and enjoy this ride through my top 10 tricky biology science questions.
What is 'Brainfreeze?'
Sphenopalatine ganglioneuralgia (or 'brain-freeze') is a painful condition similar to a migraine, that arises due to your bodys natural reaction to cold temperatures.
When you get cold, your body undergoes a series of changes designed to prevent heat loss. One of these adaptations is the constriction of blood vessels (vasoconstriction) close to the surface of the skin. With less blood flowing near to your skin, less heat is lost to the surroundings and you stay warmer for longer.
When something really cold hits the back of your mouth, the blood vesselts in your palate rapidly constrict. When you swallow, the cold goes away and the same blood vessels rapidly dilate back to their original size. All of this is a perfectly normal physiological response to the cold.
The pain is caused by a misinterpretation of this constriction/dilation by the trigeminal nerve - a major facial nerve that is positioned very close to your palate. The pain seems to come from your forehead because of the location of the trigeminal nerve (shown in the diagram)
How do Painkillers Work?
We sense pain due to the transmission of a specific signal to the brain via the spinal cord. Pain relief medications work by preventing this 'pain signal' from reaching the brain. There are two main types of painkillers that are commonly used: the 'aspirin medicines' and the 'narcotic medicines.'
The Aspirin-type painkillers block the body's prostaglandins - molecules responsible for pain and swelling. Blocking prostaglandins blocks the signal at the source of the pain, as well as reducing swelling.
The Narcotic-type medicines block the pain messages in the spinal cord and the brain, and are typically used for much more severe pain relief.
Each group of painkiller is comprised of numerous sub-types, each with slightly different modes of action. This can allow certain pain relief medicines to be combined safely.
Types of Painkiller
Mild anticoagulant - can reduce probability of stroke and heart attack
Analgesic - reduces pain and lowers temperature
Severe pain relief
Mild to moderate pain relief. Also an anti-diarrheal
What are Spots, Pimples and Boils?
Whether you are male or female, spots, pimples, and acne are all down to a sensitivity to the hormone testosterone. This hormone can trigger the overproduction of sebum - an oily substance that waterproofs your hair and skin. When sebum gets trapped, this can lead to a spot forming.
Your skin is like a conveyor belt, constantly renewing itself. As new cells are produced in the lowest layers of your skin (the dermis), old cells are shed from the surface. If some of these dead skin cells happens to block a pore, sebum can build up inside the hair follicle.
- Blackheads occur when the blockage is near the sufrace. The accumulated sebum can react with the oxygen in the air and turns black (a similar process to an apple going brown). The technical term is an 'open comedone.'
- Whiteheads occur beneath a layer of skin. This prevents the sebum from reacting with the air and so it stays white. Whiteheads are 'closed comedones.'
- Red acne spots are the result of an infection. Trapped sebum provides the ideal breeding ground for bacteria which can multiply and cause an inflammed pustule.
There is no evidence that diet affects acne, as it is caused by the presence of testosterone. This also explains why teens and pregnant women develop acne - both sets of people are subject to hormone imbalances.
Why do our Stomachs Rumble?
The classic rumble associated with hunger is less to do with the stomach and more to do with our large intestine. A rumbling tummy is a combination of liquid and gas plus a small space.
Food does not move down our digestive system by gravity - if that were the case, astronauts would not survive in space. Instead, muscle contractions in the gut wall called peristalsis both churn up the food and move it through the system. These muscle contractions occur right the way through the digestive system, from the oesophagus to the stomach to the intestines and out the other end.
When air gets trapped in the folds and bends of the small intestine, the liquid sloshing around can create a rumble - amplified by the small space of the small intestine. The reason we associate a rumbling tummy with hunger is that the rumbling is louder the less food is present in the intestine.
What are Hiccups?
An enduring tricky biology question, the actual hiccup is a strong contraction of the diaphragm - the organ responsible for our breathing. Just after the contraction we start to inhale which causes the glottis (a partioning wall between the windpipe and oesophagus) closes the windpipe, causing the 'hic' sound.
But what sets them off? There are actually over 100 physiological causes for a hiccup! The most common reasons are:
- Acid reflux
- Irritation of the thorax
- Irritation of the phrenic nerve (the nerve that controls the diaphragm)
Are X-Rays Safe?
Did you know that falling out of bed kills 450 people a year in the US?, Ants claim another 30 lives and vending machines kill around 13 people; Safety is a relative term.
An x-ray is a form of high energy radiation with a wavelength about 10,000 times shorter than that of visible light. The danger with x-rays is that they can knock electrons away from atoms, creating ions; this is why x-rays are called 'ionising radiation'. Ions are much more reactive than atoms and can shoot about your body damaging important molecules like DNA. This can cause mutation, or even cancer, if the dose is high enough.
But that is the key - 'if the dose is high enough.' The increase in radiation your body receives during an x-ray is equivalent to the extra radiation you are exposed to during a trans-atlantic flight. Medical x-rays are now very safe (the technician is in greater danger than you are due to the frequency of possible exposure), and much safer than being cut open every time a doctor needs to look inside you.
How Does a Fish Breathe Underwater?
Fish don't 'breathe' underwater, but they still need to absorb oxygen and remove oxygen in a process known as gas exchange.
The gills of a fish are made up of an arch which splits into filaments lined with lamellae - small, blood-vessel lined discs. This makes the gills extremely blood-rich giving a bright red colour. The more active a fish is, the more oxygen it needs, so the more lamellae it has.
A fish extracts the oxygen it needs from the water by diffusion. Water moves into the mouth and flows over and through the gills. The water contains a high concentration of oxygen compared to the blood which causes oxygen to diffuse into the blood (carbon dioxide is the opposite - high concentration in blood, low in water, so it diffuses out). Fish must maintain a 'countercurrent system of flow' as diffusion only works if there is less oxygen in the blood than there is in the water.
Why do we get Dizzy?
Dizziness is caused when the brain receives conflicting signals from different sensors.
The vestibular system is an intricate network of fluid-filled channels found in our inner ear and is responsible for our perception of gravity and motion. When we spin around, we set the fluid in the semicircular canal spinning. If we stop suddenly, our eyes and other sense organs immediately send a signal to the brain that the body has stopped moving. The fluid in our vestibular system, however, keeps spinning and so sends a signal to the brain that the head is moving.
The sensation of 'dizziness' occurs due to the conflict between these two signals. The brain accepts both signals as true and so decides that the head is spinning, whilst the body is stationary.
What is a Neuron?
Neurons are a speciailised cell-type that transmits information around our body at high speed. They are the information highway of our bodies and work in a similar way to an electric circuit. These highly specialised cells exhibit a number of adaptations to help them do their job:
- Dendrites: increase the surface area of the neuron to maximise the number of possible synaptic connections.
- Myelin Sheath: a fatty tissue that insulates the nerve in a similar way to the insulation on an electrical wire.
- Nodes of Ranvier: gaps in the myelin that allow the signal to 'jump' from node to node, increasing the speed of transmission.
It should be obvious that neurons do not work in isolation - many are needed to transmit a signal to its destination. The more often a series or collection of neurons are caused to fire, the easier and easier it becomes for that same pattern to be repeated: this is the basis of learning.
What are Goosebumps?
Another extremely popular biology question! Goosebumps are a relic from our ancestrally hairy days...and are now next to useless. The theory behind this physiological response is twofold:
Firstly, air is a poor conductor of heat. When cold our ancestors would fluff up their fur, trapping air and reducing heatloss. The video shows how our hairs are raised.
Secondly, many mammals fluff up their fur to appear larger and scarier when threatened or displaying during mating rituals. This is why we get goosebumps when scared.
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