Explain how the nervous system and the endocrine system are integrated to regulate body temperature when a person moves from a warm room into cold outdoor air.

IB DP Biology Higher Level (2023 syllabus) — C3.1 Integration of body systems · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Thermoreceptors in the skin sense the fall in external temperature and transmit impulses to the hypothalamus. The hypothalamus, as the integrating centre, coordinates both nervous and hormonal responses. Through the nervous system it sends efferent signals that cause vasoconstriction of skin arterioles and/or shivering of skeletal muscles, reducing heat loss and producing heat. Through the endocrine system it stimulates the anterior pituitary to release TSH, which in turn stimulates the thyroid gland to secrete thyroxine, raising the basal metabolic rate and generating additional heat.

Examiner tips

  • Use the word ‘hypothalamus’ as the integrating centre
  • Show both nervous (vasoconstriction, shivering) and endocrine (TSH, thyroxine) pathways
  • Mention thermoreceptors in the skin
  • Keep the answer concise and use correct terminology

Common mistakes

  • Confusing the hypothalamus with the pituitary as the integrating centre
  • Omitting the role of thermoreceptors
  • Failing to mention both nervous and endocrine responses

Mark scheme (4 marks)

  1. Thermoreceptors in the skin detect the drop in external temperature and send nerve impulses to the hypothalamus.
  2. The hypothalamus acts as the integrating centre and coordinates both nervous and hormonal responses.
  3. Via the nervous system, the hypothalamus sends efferent nerve impulses causing vasoconstriction of skin arterioles and/or shivering of skeletal muscles.
  4. Via the endocrine system, the hypothalamus stimulates the anterior pituitary to release TSH, which causes the thyroid gland to secrete thyroxine, increasing the basal metabolic rate to generate more heat.

Related

More Integration of body systems questions

▶ Try answering this question with AI marking (free) →