Vein
1 card- 01
Why do veins look blue under the skin when the blood inside them is red?
- A
Deoxygenated blood is blue and turns red on contact with air
- B
Skin scatters and absorbs light so that the vein reflects relatively more blue than the surrounding tissue; the blood itself is dark red
- C
Veins have blue walls
- D
It is the colour of the vein's valves
- A
Control of ventilation
1 card- 02
When you hold your breath, what creates the overwhelming urge to breathe?
- A
Rising carbon dioxide in the blood, detected by chemoreceptors in the brainstem
- B
The lungs running out of air
- C
The heart slowing down
- D
Falling oxygen in the blood
- A
Carbon monoxide poisoning
1 card- 03
Why is carbon monoxide so dangerous, when the air still contains plenty of oxygen?
- A
It destroys the lungs
- B
It binds haemoglobin over 200 times more tightly than oxygen, so the blood carries oxygen but cannot deliver enough of it
- C
It stops the heart directly
- D
It replaces oxygen in the air
- A
Red blood cell
1 card- 04
Why do mature red blood cells have no nucleus?
- A
Losing the nucleus makes room for more haemoglobin and lets the cell squeeze through capillaries, at the cost of a limited lifespan
- B
They are not really cells
- C
The nucleus would block oxygen from entering
- D
They are made without DNA
- A
Blood pressure
1 card- 05
A blood pressure reading is '120 over 80'. What do the two numbers mean?
- A
The pressure in the arteries and the pressure in the veins
- B
The pressure in the arteries when the heart contracts (systolic) and when it relaxes between beats (diastolic), in mm of mercury
- C
The heart rate and the breathing rate
- D
The pressure at the heart and at the fingertips
- A
Heart
1 card- 06
Why does the left side of the heart have a much thicker muscular wall than the right?
- A
It pumps more blood than the right side
- B
It pumps blood to the whole body at high pressure; the right side only pumps to the nearby lungs
- C
It holds the heart's pacemaker
- D
It beats more often
- A
Blood type
1 card- 07
Why can group O blood be given to almost anyone, but a group O person can only receive group O?
- A
Group O cells are smaller and pass any filter
- B
Group O red cells carry neither A nor B antigen for a recipient's antibodies to attack, but group O plasma contains antibodies against both A and B
- C
Group O blood has no antibodies of any kind
- D
Group O is the most common type
- A
Coagulation
1 card- 08
Why doesn't blood clot inside healthy blood vessels, when it clots within minutes in a cut?
- A
Clotting factors are made only at wounds
- B
Blood only clots when it meets air
- C
Clotting is triggered by contact with tissue outside the vessel lining; the intact lining actively suppresses it
- D
Moving blood cannot clot
- A
Fever
1 card- 09
Is a fever caused by the infection, or by the body?
- A
By the immune cells overheating as they fight
- B
By damaged tissue releasing stored heat
- C
By the infection: bacteria and viruses generate heat as they multiply
- D
By the body: immune signals raise the hypothalamus's set point, and the body then works to reach the new temperature
- A
Shivering
1 card- 10
Why do you shiver when you are cold?
- A
The nerves misfire in the cold
- B
To pump blood to the skin faster
- C
To shake ice off the skin
- D
Rapid involuntary muscle contractions generate heat
- A
Perspiration
1 card- 11
On a hot, humid day you sweat heavily but feel no cooler. Why?
- A
The body stops producing heat in humidity
- B
Humidity blocks the sweat glands
- C
Sweat cools only when it evaporates, and humid air cannot take up more water vapour
- D
Sweat on humid days contains less salt
- A
Immune system
1 card- 12
Why is a pus-filled, swollen, red wound not a sign that something has gone wrong?
- A
They are signs that antibiotics are needed
- B
Redness means the wound is bleeding internally
- C
Swelling shows the tissue is dying
- D
These are signs of inflammation: blood flow and white cells are being sent to the site, and pus is dead white cells and bacteria
- A
Allergy
1 card- 13
What is an allergy, in immune terms?
- A
A deficiency of the immune system
- B
A bacterial infection triggered by the allergen
- C
A toxin in the allergen that damages tissue
- D
An immune response against something harmless, such as pollen or peanut protein, treated as if it were a parasite
- A
Autoimmune disease
1 card- 14
Type 1 diabetes, coeliac disease and rheumatoid arthritis are autoimmune diseases. What do they have in common?
- A
They are all infections
- B
They are all caused by eating sugar
- C
They are all caused by a weak immune system
- D
The immune system attacks the body's own cells — insulin-producing cells, the gut lining, joint tissue
- A
Antibiotic resistance
1 card- 15
'Antibiotic resistance' means that:
- A
The patient has taken so many antibiotics that they no longer work on them
- B
Bacteria have evolved so that the drug no longer kills them
- C
The patient's body has become resistant to the drug
- D
The drug has degraded and lost its strength
- A
Stomach
1 card- 16
Stomach acid is strong enough to dissolve metal. Why doesn't it digest the stomach itself?
- A
The lining secretes a thick alkaline mucus and replaces its surface cells every few days; when this defence fails, an ulcer forms
- B
The stomach wall is made of the same material as tooth enamel
- C
Stomach cells are made of acid-proof protein
- D
The acid is only produced while food is present
- A
Gastroesophageal reflux disease
1 card- 17
What is 'heartburn'?
- A
Excess acid burning the stomach lining
- B
A mild heart problem brought on by eating
- C
Gas trapped near the heart
- D
Stomach acid leaking up into the oesophagus, which has no protective mucus layer
- A
Insulin
1 card- 18
What does insulin do?
- A
Signals cells to take glucose out of the blood and store it, lowering blood sugar after a meal
- B
Raises blood sugar when it is low
- C
Converts fat into sugar
- D
Digests sugar in the gut
- A
Blood sugar level
1 card- 19
Why do you feel sleepy after a large meal rich in refined carbohydrate?
- A
Blood is diverted from the brain to the stomach in large amounts
- B
Carbohydrate is converted directly into sleep hormones
- C
The insulin surge that follows drives blood sugar down again, and the digestive effort and hormonal signals promote drowsiness
- D
The stomach presses on the lungs
- A
Adrenaline
1 card- 20
When frightened, your heart races, your hands shake and your mouth goes dry. What connects these?
- A
The brain shuts down non-essential organs
- B
Fear damages the nerves temporarily
- C
Adrenaline and the sympathetic nervous system prepare the body to fight or flee, shifting resources to muscles and away from digestion
- D
Blood pressure drops suddenly
- A
Thyroid
1 card- 21
The thyroid gland sets the body's metabolic rate. What is the single essential ingredient it cannot make its hormones without?
- A
Vitamin C
- B
Iron
- C
Iodine, which is why table salt is often iodised
- D
Calcium
- A
Caffeine
1 card- 22
How does caffeine keep you awake?
- A
It blocks the receptors for adenosine, the molecule that accumulates during the day and signals sleepiness
- B
It raises blood sugar
- C
It speeds up the heart, which wakes the brain
- D
It supplies the brain with energy
- A
Alcohol (drug)
1 card- 23
Why does drinking alcohol make you need to urinate so often?
- A
Alcohol irritates the bladder
- B
Beer and wine are mostly water
- C
The body flushes the alcohol out through the kidneys
- D
Alcohol suppresses the hormone that tells the kidneys to conserve water, so they release more
- A
Lactic acid
1 card- 24
Is the muscle soreness you feel the day after unaccustomed exercise caused by lactic acid?
- A
Yes: the acid crystallises in the muscle
- B
No: it is caused by dehydration
- C
No: lactate is cleared within an hour; the soreness comes from microscopic damage to muscle fibres and the inflammation that repairs them
- D
Yes: lactic acid takes a day to break down
- A
Vitamin C
1 card- 25
Why do humans need vitamin C in the diet, when dogs, cats and most other mammals make their own?
- A
Humans never had the gene
- B
Our ancestors lost the gene for the last enzyme in the pathway; on a fruit-rich diet the loss did not matter
- C
Humans use up vitamin C faster
- D
Humans have a larger brain that consumes it
- A
Cholesterol
1 card- 26
Is cholesterol bad for you?
- A
No: cholesterol is only found in animals, not humans
- B
No: it is essential for every cell membrane and for making hormones; what matters is how it is carried in the blood
- C
Yes: all cholesterol comes from food and should be avoided
- D
Yes: the body has no use for it
- A
Reflex
1 card- 27
You touch a hot pan and pull your hand away before you feel the pain. How?
- A
The withdrawal reflex is wired through the spinal cord and acts before the signal has reached the brain
- B
Pain nerves are faster than movement nerves
- C
The hand has its own small brain
- D
The brain reacts and then edits your memory of the order
- A
Nerve conduction velocity
1 card- 28
Why do you feel a stubbed toe as a sharp pain first and a dull throbbing a moment later?
- A
Two kinds of pain fibre carry the signal: fast, insulated fibres for sharp pain and slow, uninsulated ones for dull pain
- B
The brain replays the signal
- C
The toe is far from the brain, so the signal arrives twice
- D
The first pain is in the skin and the second in the bone
- A
Taste
1 card- 29
Is the tongue divided into zones for sweet, salty, sour and bitter?
- A
No: taste is detected only in the throat
- B
Yes, but only in children
- C
No: every taste can be detected across the whole tongue; the 'tongue map' comes from a misread 1901 study
- D
Yes: sweet at the tip, bitter at the back
- A
Olfaction
1 card- 30
Why does a hot meal taste of almost nothing when you have a heavy cold?
- A
Mucus coats the tongue
- B
Fever dulls the nerves
- C
Most of flavour is smell; a blocked nose stops odour molecules from the mouth reaching the smell receptors
- D
The cold virus infects the taste buds
- A
Motion sickness
1 card- 31
Why do people get car-sick reading in the back seat but not when driving?
- A
Reading uses up oxygen the stomach needs
- B
The inner ear senses motion while the eyes report stillness; the brain treats the conflict like poisoning and triggers nausea
- C
Drivers have stronger stomachs
- D
Passengers breathe more exhaust
- A
Sleep
1 card- 32
Why is sleep necessary? Which of these is supported by evidence?
- A
During sleep the brain consolidates memories and clears metabolic waste; without it, cognition and immunity deteriorate within days
- B
Sleep exists only to save energy at night
- C
The body cannot repair tissue while awake
- D
Sleep is a habit with no biological function
- A
Lateralization of brain function
1 card- 33
Are some people 'left-brained' (logical) and others 'right-brained' (creative)?
- A
No: the two hemispheres are identical in function
- B
Yes: creative people have a larger right hemisphere
- C
Yes: it is determined by which hand you write with
- D
No: some functions are lateralised, but brain scans show no people who preferentially use one hemisphere
- A
Hiccup
1 card- 34
What is a hiccup?
- A
A sudden involuntary contraction of the diaphragm, followed by the vocal cords snapping shut
- B
Air escaping from the lungs
- C
A cough that starts in the throat
- D
A spasm of the stomach
- A
Yawn
1 card- 35
Why is yawning contagious?
- A
It spreads a shortage of oxygen through a room
- B
It is not contagious; people just yawn at similar times
- C
It appears to be a social reflex linked to empathy; seeing a yawn activates the same brain areas involved in imitation
- D
Yawning releases a chemical that others inhale
- A
Bone
1 card- 36
An adult has 206 bones. A newborn has around 300. What happened to the rest?
- A
The count is wrong: babies have 206 too
- B
Many of the baby's bones are separate pieces of cartilage or bone that fuse together as it grows
- C
Babies have extra fingers and toes that are lost
- D
The extra bones dissolve and are reabsorbed
- A
Knuckle cracking
1 card- 37
Does cracking your knuckles cause arthritis?
- A
Only if done more than ten times a day
- B
Yes: the sound is the bones grinding
- C
No: the sound is a gas bubble forming in the joint fluid, and studies of habitual crackers show no increase in arthritis
- D
Yes: it wears the cartilage away
- A
Hair
1 card- 38
Does shaving make hair grow back thicker or darker?
- A
Yes, but only on the face
- B
Yes: the root produces more pigment after shaving
- C
No: shaving cuts the hair at its widest point, so the blunt regrowth feels coarser, but the hair itself is unchanged
- D
Yes: cutting stimulates the follicle
- A
Skin
1 card- 39
What is the largest organ of the human body?
- A
The skin: about 2 m² and 15% of body weight, with its own blood supply, nerves and immune cells
- B
The brain
- C
The intestines
- D
The liver
- A
Sunburn
1 card- 40
What is sunburn?
- A
An allergic reaction to sunlight
- B
Skin cooked by the heat of the sun
- C
An inflammatory response to DNA damage in skin cells caused by ultraviolet light — not a heat burn
- D
Damage from infrared radiation
- A
Water intoxication
1 card- 41
Can you drink too much water?
- A
No: the body simply passes any excess
- B
Yes: drinking faster than the kidneys can excrete dilutes the blood's sodium, and the resulting brain swelling can be fatal
- C
Only if the water is contaminated
- D
No: water has no active ingredient
- A
Appendix (anatomy)
1 card- 42
Why is a burst appendix a medical emergency?
- A
It causes massive bleeding
- B
The stomach can no longer digest food
- C
It spills gut bacteria into the abdominal cavity, causing a spreading infection of the lining
- D
The appendix contains a poison
- A
Digestion
1 card- 43
Does swallowed chewing gum stay in the stomach for seven years?
- A
No: stomach acid dissolves it within hours
- B
Yes: it sticks to the stomach wall
- C
Yes: the stomach cannot break it down, so it stays
- D
No: gum base is indigestible but passes through the gut like any other roughage in a day or two
- A
Human body temperature
1 card- 44
Is normal human body temperature 37.0 °C?
- A
Roughly, but it varies by person, time of day and age, and modern averages are closer to 36.6 °C
- B
Yes, but only when measured under the arm
- C
Yes, exactly, in every healthy person
- D
No: it is 38 °C
- A
Heart rate
1 card- 45
Why do trained endurance athletes have resting heart rates as low as 40 beats per minute?
- A
They have fewer red blood cells
- B
Their blood is thinner
- C
Their metabolism has slowed down
- D
Training enlarges and strengthens the heart, so each beat pumps more blood and fewer beats are needed at rest
- A
End of deck · 45 cards