IMAT Biology · Free notes

Human Anatomy and Physiology: How the Body Systems Work

Human Anatomy and Physiology has 67 past questions since 2011, and the ministry papers from 2023 on have asked 15 of them. It is the largest Biology chapter, and nearly all of it is recall: which organ makes what, which valve is open, which ion moves and which way. The older Cambridge papers liked sequences and multi-statement items (the cardiac cycle, the steps of muscle contraction, the nephron), while the ministry papers mostly ask one direct fact, such as the job of a hormone, a cell or an organ. The difficulty sits in the near-miss options: a neighbouring structure, a reversed direction or a look-alike name, so learn each table row exactly.

The handout has every subtopic, worked example, formula and trap with answers shown. The formula sheet is the chapter’s formulas and traps alone, on one page.

IMAT home All formulas on one page

Subtopic notes

Formula & revision sheet

3 formulas · 31 reference tables · 36 gotchas across all subtopics — the exam-eve cheat-sheet

Tissues, Bone and Homeostasis

Reference tables (4)

The four basic tissue types and how they build organs7 rows

Tissue	Kind	Where found	Job
Epithelial	Squamous: flat cells, one layer thick	Alveoli, capillary walls (endothelium), Bowman's capsule	Short path for diffusion and filtration
Epithelial	Ciliated columnar, with mucus-making goblet cells	Trachea, bronchi, oviducts	Moves mucus, or an egg, along the tube
Epithelial	Cuboidal	Kidney tubules, glands	Secretion and absorption
Epithelial	Stratified squamous: many layers	Epidermis of the skin, mouth, oesophagus	Resists wear and drying
Connective	Cartilage, bone, blood, fat, tendons, ligaments	Throughout the body	Support, joining, transport, storage
Muscle	Skeletal, cardiac, smooth	Attached to bones; heart wall; walls of gut and blood vessels	Contraction
Nervous	Neurones and supporting glial cells	Brain, spinal cord, nerves	Carries electrical signals

Blood is a connective tissue: its cells sit in a liquid matrix, the plasma.

Bone cells, cartilage and the structures of a joint7 rows

Structure	What it is	Job
Osteoblast	Bone-building cell	Secretes collagen and lays down calcium phosphate to make new matrix
Osteocyte	Former osteoblast trapped in the hard matrix	Maintains the bone around it and senses mechanical load
Osteoclast	Large cell with many nuclei	Dissolves (resorbs) bone matrix, releasing calcium into the blood
Cartilage	Chondrocytes in a collagen matrix, no blood supply	Smooth, shock-absorbing joint surfaces; flexible support
Tendon	Tough, hardly stretchy bundle of collagen	Joins a muscle to a bone, so the muscle can pull it
Ligament	Collagen with some elastic fibres	Joins bone to bone and holds a joint together
Synovial membrane and fluid	Lining of a movable joint capsule	Fluid lubricates the joint and feeds the cartilage

Memory aid: osteoblasts build, osteoclasts cut away.

Homeostasis and negative feedback loops5 rows

Controlled value	Receptor	Control centre	Effectors
Core temperature	Thermoreceptors in the skin and hypothalamus	Hypothalamus	Sweat glands, skin arterioles, skeletal muscle
Blood glucose	Alpha and beta cells of the pancreatic islets	The pancreas itself	Liver, muscle and fat cells
Blood water content	Osmoreceptors in the hypothalamus	Hypothalamus, via ADH from the posterior pituitary	Collecting ducts of the kidney
Blood carbon dioxide and pH	Chemoreceptors in the medulla, aorta and carotid arteries	Medulla oblongata	Diaphragm and intercostal muscles
Blood pressure	Baroreceptors in the aorta and carotid arteries	Medulla oblongata	Heart and arterioles

Temperature control: responses to heat and to cold5 rows

Effector	Response when too hot	Response when too cold
Skin arterioles	Vasodilation: more blood flows near the surface and loses heat	Vasoconstriction: less blood flows near the surface
Sweat glands	Secrete sweat, which evaporates and removes heat	Little or no sweat
Skeletal muscle	No shivering	Shivering: rapid contractions release heat from respiration
Hair erector muscles	Relax, hairs lie flat	Contract, hairs stand up and trap air (a small effect in humans)
Metabolic rate	Not raised	Raised by thyroxine and adrenaline

Watch out for (4)

Skin is an organ, endothelium is a tissue
→ The four basic tissue types and how they build organs
Tendons join muscle to bone, ligaments join bone to bone
→ Bone cells, cartilage and the structures of a joint
Positive feedback does not mean good feedback
→ Homeostasis and negative feedback loops
Capillaries do not move towards the skin
→ Temperature control: responses to heat and to cold

The Heart, the Cardiac Cycle and Blood Vessels

Formulas (1)

Cardiac output, stroke volume and heart rate · Cardiac output $CO = SV \times HR \qquad SV = EDV - ESV$

Reference tables (3)

Double circulation and the main blood vessels8 rows

Vessel	From and to	Oxygen content	Notable feature
Aorta	Left ventricle to the body	High	Highest blood pressure
Pulmonary artery	Right ventricle to the lungs	Low	The only artery with deoxygenated blood; high $\mathrm{CO_2}$
Pulmonary vein	Lungs to the left atrium	High	The only vein with oxygenated blood; lowest $\mathrm{CO_2}$
Venae cavae	Body to the right atrium	Low	Lowest blood pressure
Hepatic portal vein	Gut to the liver	Low	Highest glucose and amino acids after a meal
Hepatic vein	Liver to the vena cava	Low	Carries the urea the liver has just made
Renal artery	Aorta to the kidney	High	Still carries urea to be removed
Renal vein	Kidney to the vena cava	Low	Lowest urea concentration in the body

Heart structure, the pacemaker and the control of heart rate6 rows

Structure	Where	Job
Sinoatrial node (SAN)	Wall of the right atrium	Pacemaker: starts each wave of excitation, which spreads over both atria
Atrioventricular node (AVN)	Between the atria and the ventricles	Delays the wave by about 0.1 s so the atria empty first
Bundle of His and Purkinje fibres	In the septum and the ventricle walls	Carry the wave to the apex, so the ventricles contract from the bottom up
AV valves	Between each atrium and ventricle	Stop backflow into the atria when the ventricles contract
Semilunar valves	At the base of the aorta and the pulmonary artery	Stop backflow into the ventricles when they relax
Cardiovascular centre	Medulla oblongata	Adjusts heart rate through sympathetic and parasympathetic nerves

The cardiac cycle: pressure changes and valve positions5 rows

Phase	Atria	Ventricles	AV valves	Semilunar valves
Atrial systole	Contract: volume falls, pressure rises	Relaxed, receiving the last blood	Open	Closed
Start of ventricular systole	Relaxed, begin to fill	Contract; pressure rises above the atria but not yet above the arteries	Closed (first sound)	Closed
Ventricular ejection	Relaxed, filling	Pressure above the aorta and pulmonary artery: blood leaves	Closed	Open
Start of ventricular diastole	Relaxed, filling	Relax; pressure falls below the arteries	Closed	Close (second sound)
Passive filling	Relaxed; blood flows through	Relaxed; pressure below the atria	Open	Closed

Watch out for (5)

Artery does not mean oxygenated
→ Double circulation and the main blood vessels
The brain changes the heart rate but does not start the beat
→ Heart structure, the pacemaker and the control of heart rate
Valves follow pressure, not timing words
→ The cardiac cycle: pressure changes and valve positions
Left and right contract together
→ The cardiac cycle: pressure changes and valve positions
Convert litres to millilitres before dividing
→ Cardiac output, stroke volume and heart rate

Blood Cells, Immune Defences and Blood Groups

Reference tables (5)

Blood: plasma, red cells, white cells and platelets6 rows

Component	Structure	Main job
Plasma	Water with glucose, amino acids, ions, urea, hormones and plasma proteins (albumin, fibrinogen, antibodies)	Transport; carries most $\mathrm{CO_2}$ as hydrogencarbonate ions
Red blood cell (erythrocyte)	Biconcave disc, no nucleus, full of haemoglobin	Carries $\mathrm{O_2}$ from the lungs to the tissues
Neutrophil	Lobed nucleus, granular cytoplasm; the commonest white cell	Phagocytosis; first to arrive at an infection
Monocyte and macrophage	Large cell with a kidney-shaped nucleus; becomes a macrophage in tissues	Phagocytosis and presenting antigens to lymphocytes
Lymphocyte	Large round nucleus, little cytoplasm	Specific immunity: B cells make antibodies, T cells kill or coordinate
Platelet	Cell fragment without a nucleus	Starts blood clotting

Non-specific defences: barriers, phagocytes and inflammation6 rows

Defence	How it works	Where
Skin	Tough outer layer of dead keratinised cells; slightly acidic surface	Body surface
Mucus and cilia	Mucus traps microbes and dust; cilia sweep it up to the throat	Airways
Stomach acid	pH about 2 kills most swallowed microbes	Stomach
Lysozyme	Enzyme that breaks bacterial cell walls	Tears, saliva, nasal mucus
Phagocytes	Engulf and digest pathogens	Blood and tissues
Inflammation	Histamine causes vasodilation and leaky capillaries	Site of injury or infection

B and T lymphocytes, antibodies and immune memory5 rows

Cell	Made in	Matures in	Job
B lymphocyte	Bone marrow	Bone marrow	Binds antigen, divides, becomes plasma cells and memory cells
Plasma cell	Lymph nodes and spleen, from a B cell	Already mature	Secretes large amounts of one antibody
Helper T cell	Bone marrow	Thymus	Releases cytokines that activate B cells, killer T cells and macrophages; the cell HIV destroys
Cytotoxic (killer) T cell	Bone marrow	Thymus	Kills body cells infected by viruses, and cancer cells
Memory B and T cells	Bone marrow	As their parent cell	Survive for years and start a fast secondary response

Active and passive immunity, and how vaccines work4 rows

Type	How it is gained	Memory cells	Example
Natural active	Catching the disease	Yes, long-lasting	Immunity after recovering from measles
Artificial active	Vaccination	Yes, long-lasting	The measles, mumps and rubella vaccine
Natural passive	Antibodies cross the placenta, or come in breast milk	No, lasts weeks to months	Protection of a newborn baby
Artificial passive	Injection of ready-made antibodies	No, lasts weeks	Antivenom after a snake bite; tetanus antitoxin

ABO and Rhesus blood groups, transfusions and transplants5 rows

Blood group	Antigens on red cells	Antibodies in plasma	Can safely receive red cells from
A	A	Anti-B	A and O
B	B	Anti-A	B and O
AB	A and B	Neither	A, B, AB and O
O	Neither	Anti-A and anti-B	O only
Rh negative	No D antigen	Anti-D only after exposure	Rh negative only

Watch out for (5)

Red cells do not fight infection or clot blood
→ Blood: plasma, red cells, white cells and platelets
Beta cells are not immune cells
→ Non-specific defences: barriers, phagocytes and inflammation
B for bone marrow, T for thymus
→ B and T lymphocytes, antibodies and immune memory
Passive immunity has no memory
→ Active and passive immunity, and how vaccines work
Universal donor means no antigens, not no antibodies
→ ABO and Rhesus blood groups, transfusions and transplants

Airways, Breathing and Gas Transport

Formulas (1)

Minute ventilation and dead space · Ventilation $V_E = V_T \times f \qquad V_A = (V_T - V_D) \times f$

Reference tables (3)

The airway from the nose to the alveoli6 rows

Structure	Tissues	Job
Nasal cavity	Ciliated epithelium, mucus, many blood vessels	Filters, warms and moistens air
Epiglottis	Elastic cartilage	Closes the larynx when swallowing
Trachea	C-shaped cartilage rings, ciliated epithelium with goblet cells, smooth muscle	Kept open by cartilage; mucus and cilia remove dirt
Bronchi	Cartilage plates, ciliated epithelium	Carry air into each lung
Bronchioles	Smooth muscle and elastic fibres, no cartilage	Branch through the lung; adjust airflow
Alveoli	Squamous epithelium, elastic fibres, surfactant	Gas exchange with the capillaries

Inhaling and exhaling: volume and pressure changes5 rows

Feature	Inhalation	Quiet exhalation
Diaphragm	Contracts, flattens and moves down	Relaxes and domes upward
External intercostal muscles	Contract: ribs move up and out	Relax: ribs move down and in
Volume of the thorax	Increases	Decreases
Pressure in the lungs	Falls below atmospheric pressure	Rises above atmospheric pressure
Air flow	Into the lungs	Out of the lungs

Carrying oxygen and carbon dioxide: haemoglobin and the Bohr effect5 rows

Situation	Effect on affinity for oxygen	Result
Lungs: high partial pressure of oxygen	Haemoglobin loads oxygen	Blood leaves about 97% saturated
Active muscle: high carbon dioxide, low pH, warm	Affinity falls; curve shifts right (Bohr effect)	More oxygen unloaded to the muscle
Fetal haemoglobin	Higher affinity; curve lies to the left	Takes oxygen from the mother's blood in the placenta
Myoglobin in muscle	Much higher affinity; far to the left	Stores oxygen and releases it only when oxygen is very low
Carbon monoxide	Binds haem about 200 times more strongly than oxygen	Less oxygen carried; can be fatal

Watch out for (4)

Gas exchange happens only in the alveoli
→ The airway from the nose to the alveoli
The diaphragm moves down when you breathe in
→ Inhaling and exhaling: volume and pressure changes
Fast shallow breathing wastes air
→ Minute ventilation and dead space
High carbon dioxide lowers affinity, it does not raise it
→ Carrying oxygen and carbon dioxide: haemoglobin and the Bohr effect

The Digestive System, Enzymes and Absorption

Reference tables (4)

Organs of the digestive system and what each one does9 rows

Organ	Main job	Secretes
Mouth	Chewing; starts starch digestion	Saliva: salivary amylase and mucus
Oesophagus	Moves food to the stomach by peristalsis	Mucus
Stomach	Stores and churns food, starts protein digestion, kills microbes	$\mathrm{HCl}$ , pepsinogen, mucus; the hormone gastrin
Duodenum	Receives bile and pancreatic juice; most chemical digestion	Mucus, brush-border enzymes; hormones secretin and CCK
Ileum	Absorbs the products of digestion	Brush-border enzymes
Large intestine	Absorbs water and ions; gut bacteria make vitamin K	Mucus
Liver	Makes bile; stores glycogen; makes urea	Bile (into the bile duct)
Gall bladder	Stores and concentrates bile	Releases bile after a fatty meal
Pancreas	Exocrine: digestive juice. Endocrine: insulin and glucagon	Pancreatic juice with enzymes and $\mathrm{HCO_3^-}$

Digestive enzymes: source, substrate, product and best pH8 rows

Enzyme	Made by	Substrate and product	Best pH
Salivary amylase	Salivary glands	Starch to maltose	About 7
Pepsin	Stomach wall, as pepsinogen	Proteins to shorter polypeptides	About 2
Pancreatic amylase	Pancreas	Starch to maltose	Slightly alkaline
Trypsin	Pancreas, as trypsinogen	Proteins to peptides	Slightly alkaline
Lipase	Pancreas	Triglycerides to fatty acids and monoglycerides (and glycerol)	Slightly alkaline
Maltase	Brush border of the small intestine	Maltose to glucose	Slightly alkaline
Lactase and sucrase	Brush border	Lactose to glucose and galactose; sucrose to glucose and fructose	Slightly alkaline
Peptidases	Brush border and pancreas	Peptides to amino acids	Slightly alkaline

Bile, pancreatic juice and the control of pH in the gut4 rows

Secretion	Made by	Contains	Effect
Gastric juice	Stomach wall	$\mathrm{HCl}$ , pepsinogen, mucus	Lowers pH to about 2; starts protein digestion
Bile	Liver (stored in the gall bladder)	Bile salts, hydrogencarbonate, bilirubin; no enzymes	Emulsifies fats; helps neutralise acid
Pancreatic juice	Exocrine cells of the pancreas	Hydrogencarbonate, amylase, trypsinogen, lipase	Neutralises acid; digests all three food types
Intestinal secretions	Lining of the small intestine	Mucus and brush-border enzymes	Finish digestion

Absorption in the small intestine and the main nutrients5 rows

Product	How it enters the cells	Where it goes next
Glucose and galactose	Co-transport with sodium ions	Blood capillaries, then the hepatic portal vein to the liver
Fructose	Facilitated diffusion	Blood capillaries, then the hepatic portal vein
Amino acids	Co-transport with sodium ions	Blood capillaries, then the hepatic portal vein
Fatty acids and monoglycerides	Diffusion through the membrane	Rebuilt into fats, then into the lacteals (lymph)
Water	Osmosis	Blood (small and large intestine)

Watch out for (4)

The stomach digests; the small intestine absorbs
→ Organs of the digestive system and what each one does
Amylase makes maltose; it does not digest it
→ Digestive enzymes: source, substrate, product and best pH
Emulsifying is not digesting
→ Bile, pancreatic juice and the control of pH in the gut
Fats bypass the hepatic portal vein
→ Absorption in the small intestine and the main nutrients

The Kidney, the Nephron and Water Balance

Formulas (1)

Net filtration pressure in the glomerulus · Net filtration pressure $P_{\text{net}} = P_G - (P_C + \pi_G)$

Reference tables (2)

The nephron: filtration, reabsorption and secretion6 rows

Region	What happens	Water reabsorbed here?
Glomerulus and Bowman's capsule	Ultrafiltration: water, glucose, amino acids, ions and urea leave the blood	No: this is filtration, not reabsorption
Proximal convoluted tubule	Reabsorbs all glucose and amino acids and most $\mathrm{Na^+}$ ; cells have microvilli and many mitochondria	Yes, about two thirds of it
Descending limb of the loop of Henle	Permeable to water, which leaves into the salty medulla	Yes
Ascending limb of the loop of Henle	Pumps out $\mathrm{Na^+}$ and $\mathrm{Cl^-}$ , making the medulla salty; impermeable to water	No
Distal convoluted tubule	Adjusts $\mathrm{Na^+}$ , $\mathrm{K^+}$ and $\mathrm{H^+}$ (blood pH)	Some
Collecting duct	Water leaves by osmosis into the salty medulla, controlled by ADH	Yes, a variable amount

Osmoregulation: ADH, aldosterone and the concentration of urine4 rows

Situation	ADH release	Collecting duct	Urine
Dehydration, sweating or a salty meal	Increases	More aquaporins, more water reabsorbed	Small volume, concentrated
Drinking a lot of water	Decreases	Fewer aquaporins, less water reabsorbed	Large volume, dilute
Alcohol, or a drug that blocks ADH release	Decreases	Less water reabsorbed	Large volume; lower urea concentration
Damage to the posterior pituitary	Little or none	Almost no water reabsorbed there	Very large volumes of dilute urine

Watch out for (4)

Urea is in every part of the nephron
→ The nephron: filtration, reabsorption and secretion
The glomerulus filters; it does not reabsorb
→ The nephron: filtration, reabsorption and secretion
Blood proteins oppose filtration
→ Net filtration pressure in the glomerulus
Less ADH means more urine but lower urea concentration
→ Osmoregulation: ADH, aldosterone and the concentration of urine

Nerve Impulses, Synapses, Reflexes and Muscle Contraction

Reference tables (5)

Resting potential, action potential and conduction speed5 rows

Stage	Membrane potential	What the ions do
Resting	About $-70\ \text{mV}$	Pump moves $\mathrm{Na^+}$ out and $\mathrm{K^+}$ in; $\mathrm{K^+}$ leaks out
Depolarisation	Rises past threshold (about $-55\ \text{mV}$ ) to about $+30\ \text{mV}$	Voltage-gated $\mathrm{Na^+}$ channels open; $\mathrm{Na^+}$ floods in
Repolarisation	Falls back towards $-70\ \text{mV}$	$\mathrm{Na^+}$ channels close; voltage-gated $\mathrm{K^+}$ channels open; $\mathrm{K^+}$ flows out
Hyperpolarisation	Briefly below resting, about $-80\ \text{mV}$	$\mathrm{K^+}$ channels are slow to close
Refractory period	Returning to rest	$\mathrm{Na^+}$ channels cannot reopen yet

The cholinergic synapse and the neuromuscular junction6 rows

Step	Event
1	An action potential arrives at the presynaptic knob
2	Voltage-gated $\mathrm{Ca^{2+}}$ channels open and $\mathrm{Ca^{2+}}$ diffuses into the knob
3	Vesicles fuse with the membrane and release ACh into the cleft by exocytosis
4	ACh diffuses across the cleft and binds receptors on the postsynaptic membrane
5	$\mathrm{Na^+}$ channels linked to the receptors open; $\mathrm{Na^+}$ enters and the membrane depolarises; at threshold a new action potential starts
6	Acetylcholinesterase hydrolyses ACh; the choline is taken back and ACh is remade using ATP

Reflex arcs and the sympathetic and parasympathetic systems6 rows

Target	Sympathetic effect	Parasympathetic effect
Heart rate	Increases	Decreases (vagus nerve)
Bronchioles	Widen	Narrow
Pupil	Dilates	Constricts
Gut movement and secretion	Decrease	Increase
Saliva	Small amount, thick	Large amount, watery
Adrenal medulla	Stimulated to release adrenaline	No effect

Muscle types, skeletal muscle structure and the sarcomere bands5 rows

Band or line	What it contains	During contraction
A band	The whole length of the thick (myosin) filaments, with overlapping actin	Stays the same length
I band	Thin (actin) filaments only	Gets shorter
H zone	Thick filaments only, in the centre	Gets shorter and may disappear
Z line	Anchors the thin filaments at each end of a sarcomere	Z lines move closer together
M line	Holds the thick filaments at the centre	Stays at the centre

A sarcomere runs from one Z line to the next.

From nerve impulse to cross-bridge cycle: calcium, troponin and ATP8 rows

Step	Event
1	Acetylcholine at the neuromuscular junction depolarises the muscle fibre membrane (sarcolemma)
2	The depolarisation spreads down the T-tubules into the fibre
3	The sarcoplasmic reticulum releases $\mathrm{Ca^{2+}}$ , which diffuses into the sarcoplasm
4	$\mathrm{Ca^{2+}}$ binds troponin; troponin changes shape and moves tropomyosin off the myosin-binding sites on actin
5	A myosin head, already carrying ADP and phosphate, binds actin: a cross-bridge forms
6	ADP and phosphate are released and the head tilts: the power stroke pulls actin towards the centre
7	A new ATP binds the head, which detaches from actin
8	The head hydrolyses ATP and re-cocks, ready for the next cycle

Watch out for (5)

Synapses and long axons do not speed up transmission
→ Resting potential, action potential and conduction speed
Breaking down the transmitter is not what makes a synapse one-way
→ The cholinergic synapse and the neuromuscular junction
Count only the synapses inside the CNS
→ Reflex arcs and the sympathetic and parasympathetic systems
The filaments slide; they do not shorten
→ Muscle types, skeletal muscle structure and the sarcomere bands
Calcium binds troponin, and ATP makes myosin let go
→ From nerve impulse to cross-bridge cycle: calcium, troponin and ATP

The Brain, the Eye, Hormones and Reproduction

Reference tables (5)

Regions of the brain and their functions9 rows

Region	Main functions
Cerebrum (cerebral cortex)	Conscious thought, memory, language, voluntary movement, interpreting senses
Corpus callosum	Links the left and right hemispheres
Hippocampus	Forming new long-term memories
Amygdala	Emotions, especially fear
Thalamus	Relays sensory signals to the cortex
Hypothalamus	Body temperature, water balance, hunger and thirst; controls the pituitary
Pineal gland	Secretes melatonin at night; regulates the circadian rhythm of sleep
Cerebellum	Balance, posture and coordination of movement
Medulla oblongata	Heart rate, breathing rate, blood pressure; reflexes such as swallowing and coughing

The eye: its parts, rods and cones, and how light is detected9 rows

Part	Function
Cornea	Transparent front; does most of the bending of light; has no blood vessels
Iris	Coloured muscular ring that controls the size of the pupil
Lens	Fine focusing; changes shape for near and far objects
Ciliary muscle and suspensory ligaments	Change the shape of the lens
Retina	Contains the rods and cones
Fovea	Only cones; the sharpest vision
Blind spot	Where the optic nerve leaves; no rods or cones
Choroid	Blood vessels and dark pigment that stops light reflecting inside the eye
Sclera	Tough white outer coat

Endocrine glands, their hormones and how hormones act10 rows

Gland	Hormone	Chemical type	Main effect
Anterior pituitary	FSH, LH, TSH, ACTH, growth hormone, prolactin	Peptide and protein	Controls the gonads, thyroid and adrenal cortex; growth; milk production
Posterior pituitary	ADH and oxytocin (made in the hypothalamus)	Peptide	Water reabsorption in the kidney; uterine contraction and milk release
Thyroid	Thyroxine; calcitonin	Amine (contains iodine); peptide	Raises metabolic rate; lowers blood $\mathrm{Ca^{2+}}$
Parathyroids	Parathyroid hormone	Peptide	Raises blood $\mathrm{Ca^{2+}}$
Adrenal medulla	Adrenaline	Amine	Fight or flight: raises heart rate, breathing rate and blood glucose
Adrenal cortex	Cortisol; aldosterone	Steroid	Raises blood glucose in stress; increases $\mathrm{Na^+}$ reabsorption
Pancreas (islets)	Insulin (beta cells); glucagon (alpha cells)	Peptide	Lowers and raises blood glucose
Ovaries	Oestrogen, progesterone	Steroid	Female characteristics; build and keep the uterine lining
Testes	Testosterone	Steroid	Male characteristics; sperm production
Pineal gland	Melatonin	Amine	Daily sleep rhythm

Blood glucose control: insulin, glucagon and adrenaline4 rows

Hormone	Made by	Released when	Effects
Insulin	Beta cells of the islets	Blood glucose is high	Glucose uptake into muscle and fat; glycogen and fat made; blood glucose falls
Glucagon	Alpha cells of the islets	Blood glucose is low	Liver breaks down glycogen and makes new glucose; blood glucose rises
Adrenaline	Adrenal medulla	Stress, fear or exercise	Glycogen breakdown in liver and muscle; blood glucose rises fast
Cortisol	Adrenal cortex	Long-term stress	Gluconeogenesis; blood glucose rises

Reproductive organs, the menstrual cycle, pregnancy and birth7 rows

Hormone	Made by	Role
FSH	Anterior pituitary	Growth of a follicle; sperm production in males
LH	Anterior pituitary	A surge triggers ovulation and forms the corpus luteum; testosterone production in males
Oestrogen	Growing follicle	Rebuilds the uterine lining; a high level triggers the LH surge
Progesterone	Corpus luteum, later the placenta	Keeps the lining thick; inhibits FSH and LH
hCG	The early embryo	Keeps the corpus luteum alive; detected by pregnancy tests
Oxytocin	Made in the hypothalamus, released by the posterior pituitary	Uterine contractions in labour; milk release
Prolactin	Anterior pituitary	Milk production

Watch out for (5)

Cerebrum and cerebellum are easy to swap
→ Regions of the brain and their functions
Retinal, retinol, opsin and opsonin
→ The eye: its parts, rods and cones, and how light is detected
Hormones do not flow down ducts
→ Endocrine glands, their hormones and how hormones act
Glucagon is a hormone; glycogen is the store
→ Blood glucose control: insulin, glucagon and adrenaline
Progesterone comes from the corpus luteum, not the pituitary
→ Reproductive organs, the menstrual cycle, pregnancy and birth

PYQ weightage by concept

34 concepts · 0 PYQs — where the marks actually sit, so you know what to drill first

Tissues, Bone and Homeostasis0 PYQs · 0%

Concept	PYQs	Share
The four basic tissue types and how they build organsfoundation	—	—
Bone cells, cartilage and the structures of a jointfoundation	—	—
Homeostasis and negative feedback loopsfoundation	—	—
Temperature control: responses to heat and to coldfoundation	—	—

The Heart, the Cardiac Cycle and Blood Vessels0 PYQs · 0%

Concept	PYQs	Share
Double circulation and the main blood vesselsfoundation	—	—
Heart structure, the pacemaker and the control of heart ratefoundation	—	—
The cardiac cycle: pressure changes and valve positionsfoundation	—	—
Cardiac output, stroke volume and heart ratefoundation	—	—

Blood Cells, Immune Defences and Blood Groups0 PYQs · 0%

Concept	PYQs	Share
Blood: plasma, red cells, white cells and plateletsfoundation	—	—
Non-specific defences: barriers, phagocytes and inflammationfoundation	—	—
B and T lymphocytes, antibodies and immune memoryfoundation	—	—
Active and passive immunity, and how vaccines workfoundation	—	—
ABO and Rhesus blood groups, transfusions and transplantsfoundation	—	—

Airways, Breathing and Gas Transport0 PYQs · 0%

Concept	PYQs	Share
The airway from the nose to the alveolifoundation	—	—
Inhaling and exhaling: volume and pressure changesfoundation	—	—
Minute ventilation and dead spacefoundation	—	—
Carrying oxygen and carbon dioxide: haemoglobin and the Bohr effectfoundation	—	—

The Digestive System, Enzymes and Absorption0 PYQs · 0%

Concept	PYQs	Share
Organs of the digestive system and what each one doesfoundation	—	—
Digestive enzymes: source, substrate, product and best pHfoundation	—	—
Bile, pancreatic juice and the control of pH in the gutfoundation	—	—
Absorption in the small intestine and the main nutrientsfoundation	—	—

The Kidney, the Nephron and Water Balance0 PYQs · 0%

Concept	PYQs	Share
The nephron: filtration, reabsorption and secretionfoundation	—	—
Net filtration pressure in the glomerulusfoundation	—	—
Osmoregulation: ADH, aldosterone and the concentration of urinefoundation	—	—

Nerve Impulses, Synapses, Reflexes and Muscle Contraction0 PYQs · 0%

Concept	PYQs	Share
Resting potential, action potential and conduction speedfoundation	—	—
The cholinergic synapse and the neuromuscular junctionfoundation	—	—
Reflex arcs and the sympathetic and parasympathetic systemsfoundation	—	—
Muscle types, skeletal muscle structure and the sarcomere bandsfoundation	—	—
From nerve impulse to cross-bridge cycle: calcium, troponin and ATPfoundation	—	—

The Brain, the Eye, Hormones and Reproduction0 PYQs · 0%

Concept	PYQs	Share
Regions of the brain and their functionsfoundation	—	—
The eye: its parts, rods and cones, and how light is detectedfoundation	—	—
Endocrine glands, their hormones and how hormones actfoundation	—	—
Blood glucose control: insulin, glucagon and adrenalinefoundation	—	—
Reproductive organs, the menstrual cycle, pregnancy and birthfoundation	—	—