A chemical messenger made by an endocrine gland that travels in the blood and affects target organs.

How are hormones carried from the gland that made them to the organ they affect?

They are released into the bloodstream and carried dissolved in the blood plasma.

Name four endocrine glands in the human body.

The pituitary gland, the thyroid gland, the pancreas and the adrenal glands.

Where are the adrenal glands found?

One sits just above each kidney.

OCR GCSE Biology A J247

Cell Level Systems

Topic overview Microscopy, and sub-cellular structures DNA structure: polymer, double helix and nucleotides Enzyme action, and investigating enzymes Cellular respiration as an exothermic process Aerobic and anaerobic respiration compared Synthesis and breakdown of carbohydrates, proteins and lipids Photosynthesis: producers and the process Photosynthesis as endothermic, and investigating it Limiting factors in photosynthesis

Community Level Systems

Topic overview Cycling materials, and the role of microorganisms The carbon and water cycles, and decomposition Levels of organisation, and abiotic and biotic factors Interdependence, competition and trophic levels Pyramids of biomass and the efficiency of transfer

Genes, Inheritance and Selection

Topic overview Genetic terms, and the genome Genome, environment and mutations Asexual and sexual reproduction compared Haploid, diploid and meiosis Single gene inheritance and Punnett squares Sex determination, multiple genes and Mendel's work Variation within a population, and classification Natural selection and evolution Evidence for evolution, and the work of Darwin and Wallace

Global Challenges

Topic overview Field investigations, and human impact on ecosystems Maintaining biodiversity, monitoring conservation and ecotourism Food security, agricultural and biotechnological solutions Selective breeding and genetic engineering Health, disease, and types of disease Interactions between diseases, and how they spread Reducing the spread of disease, and named examples Physical and chemical plant defences White blood cells, antibodies and platelets Non-specific defences and the immune system Vaccines, medicines and aseptic technique Developing new medicines, and non-communicable disease Treating cardiovascular disease, and lifestyle factors Cancer, and the use of stem cells in medicine Gene technology in medicine, and the human genome

Organism Level Systems

Topic overview The nervous system and coordinated responses The reflex arc The eye and its common defects The structure and function of the brain Hormones and the endocrine glands Hormones in reproduction and the menstrual cycle Methods of contraception Tropisms, auxin and the roles of plant hormones Homeostasis, and the skin in temperature control Insulin and the control of blood glucose Type 1 and type 2 diabetes Osmotic changes in body fluids, and the kidneys Kidney structure and the parts of the tubule

Scaling Up

Topic overview Diffusion, osmosis and active transport Mitosis, the cell cycle and cell differentiation Stem cells in animals and meristems in plants Surface area to volume ratio and exchange surfaces The circulatory system, the heart and blood vessels Red blood cells and plasma Root hair cells, transpiration and translocation Xylem and phloem Factors affecting water uptake, and the potometer

Organism Level Systems

Hormones and the endocrine glands

3 things to know
Paper 1

Overview

What a hormone and an endocrine gland are, how hormones travel in the blood yet affect only some organs, the main endocrine glands including the adrenal glands, the hormones of the ovaries and testes, and how hormonal and nervous responses compare.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What is a hormone?

Key term

What is an endocrine gland?

Key term

A hormone reaches every organ, so why does it affect only some of them?

Questions from this subtopic

Each one with the model answer underneath.

1
What is a hormone?
Model answer
A chemical messenger made by an endocrine gland that travels in the blood and affects target organs.
2
How are hormones carried from the gland that made them to the organ they affect?
Model answer
They are released into the bloodstream and carried dissolved in the blood plasma.
3
What is an endocrine gland?
Model answer
A gland that releases its hormones directly into the blood rather than through a duct.
4
A hormone reaches every organ, so why does it affect only some of them?
Model answer
Only the target organs have cells carrying receptors that the hormone molecule fits, so only those cells respond.
5
Name four endocrine glands in the human body.
Model answer
The pituitary gland, the thyroid gland, the pancreas and the adrenal glands.
6
Where are the adrenal glands found?
Model answer
One sits just above each kidney.

See the rest and revise

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book

2Open book

3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Cell Level Systems

Community Level Systems

Genes, Inheritance and Selection

Global Challenges

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

Algae and .

phytoplanktonfungianimals

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AA diet high in sugar and fat leads to obesity.

BBody cells then respond poorly to insulin.

CBlood glucose concentration cannot be controlled.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Egestion means passing out of undigested food as faeces.

TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Organism Level Systems, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Start revising, £5 a month See how the method works

Or £46 a year, about £3.83 a month. Cancel anytime.