A chemical secreted by a gland straight into the bloodstream, which produces an effect on a target organ.

How does a hormone reach the organ it affects?

It is carried there dissolved in the blood.

Compare the speed and the duration of hormonal effects with nervous ones.

Hormonal effects are slower to begin, but they last for much longer.

A hormone travels all round the body, so why does it affect only certain organs?

Only its target organs respond to it.

Suggest why a reflex is controlled by the nervous system rather than by hormones.

A reflex has to be almost instant, and nervous impulses travel far faster than hormones carried in the blood.

AQA GCSE Combined Science Biology 8464

Bioenergetics

Topic overview The photosynthesis reaction and the uses of glucose Rate of photosynthesis Why organisms respire, and aerobic versus anaerobic The equations for respiration, and fermentation Response to exercise Metabolism

Cell Biology

Topic overview Eukaryotes and prokaryotes Animal and plant cells Cell specialisation and differentiation Microscopy Chromosomes, mitosis and the cell cycle Stem cells in embryos, adults and meristems Therapeutic cloning, its risks, and cloning plants Diffusion and the factors affecting its rate Surface area to volume ratio and exchange surfaces Osmosis Active transport

Ecology

Topic overview Levels of organisation in an ecosystem, and what organisms need Competition, interdependence and stable communities Abiotic factors Biotic factors Adaptations Producers, food chains and sampling with quadrats and transects Predators, prey and measuring population size How materials are cycled Waste management and biodiversity Land use, deforestation and global warming Maintaining biodiversity

Homeostasis and Response

Topic overview Homeostasis The nervous system and the reflex arc Human endocrine system Insulin, glucagon and diabetes Hormones in human reproduction Contraception The use of hormones to treat infertility Negative feedback

Infection and Response

Topic overview Communicable (infectious) diseases Viral diseases Bacterial diseases Fungal and protist diseases Human defence systems Vaccination Antibiotics and painkillers Discovery and development of drugs

Inheritance, Variation and Evolution

Topic overview Sexual and asexual reproduction Meiosis DNA and the genome Genetic terms, dominant and recessive alleles Punnett squares, probability and genetic crosses Inherited disorders and sex determination Variation Evolution Selective breeding What genetic engineering is, and what it is used for GM crops, their risks, and the steps of the process Evidence for evolution, and extinction Fossils Resistant bacteria Classification of living organisms

Organisation

Topic overview Levels of organisation, and how enzymes work Amylase, proteases and lipases Bile, food tests and the effect of pH on amylase The heart, the lungs and double circulation The pacemaker, the blood vessels and the blood Coronary heart disease: a non-communicable disease Health issues Risk factors and causal mechanisms in disease Sampling, correlation and interpreting risk data Cancer Plant tissues, and transpiration and its rate Root hair cells, xylem, phloem and stomata

Homeostasis and Response

Human endocrine system

3 things to know
Biology Paper 2

Overview

What a hormone is and how it travels in the blood, hormonal against nervous effects, the pituitary as master gland, and the thyroid, adrenals, pancreas, ovaries and testes.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What is a hormone, what makes up the endocrine system, and how do hormonal effects compare with nervous ones in speed and duration?

Key term

What is a hormone?

Key term

What is the endocrine system made up of?

Questions from this subtopic

Each one with the model answer underneath.

1
What is a hormone?
Model answer
A chemical secreted by a gland straight into the bloodstream, which produces an effect on a target organ.
2
What is the endocrine system made up of?
Model answer
Glands that secrete hormones directly into the blood.
3
How does a hormone reach the organ it affects?
Model answer
It is carried there dissolved in the blood.
4
Compare the speed and the duration of hormonal effects with nervous ones.
Model answer
Hormonal effects are slower to begin, but they last for much longer.
5
A hormone travels all round the body, so why does it affect only certain organs?
Model answer
Only its target organs respond to it.
6
Suggest why a reflex is controlled by the nervous system rather than by hormones.
Model answer
A reflex has to be almost instant, and nervous impulses travel far faster than hormones carried in the blood.

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AA rise is corrected by insulin.

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