2 - The Endocrine System

Question 1

Define the endocrine system

Answer 1

An important communication system in the body, based on chemical signals that are transmitted in the form of hormones

Question 2

Outline how the endocrine system works

Answer 2

• Glands in the body produce hormones
• Hormones are secreted into the bloodstream
• Hormones affect target organs (with receptor cells to match the hormone)

Question 3

What regulates the endocrine system + triggers glands to make and secrete hormones?

Answer 3

Hypothalamus + pituitary gland

Question 4

Define a gland

Answer 4

Organ in the body that synthesises substances such as hormones

Question 5

Define a hormone

Answer 5

Biochemical substance that circulates in the blood + affects target organs

Question 6

Give 2 examples of hormones (which glands produce them + their role)

Answer 6

1) Thyroxine
- Produced by: thyroid gland
- Role: increases heart rate, increases metabolic rate

2) Adrenaline
- Produced by: adrenal gland
- Role: multiple, including… increased heart rate/blood flow to muscles and brain, increased breathing/oxygen flow to muscles and brain

Question 7

Where is the pituitary gland + what does it do?

Answer 7

• In the brain (controlled by the hypothalamus)

- The ‘master gland’ that controls the secretion of hormones from other glands

Question 8

What is the fight or flight response?

Answer 8

Way an animal responds when its stressed. Body is physiologically aroused in readiness to fight an aggressor or flee.

Question 9

What systems are involved in the fight or flight response?

Answer 9

• The Autonomic Nervous System (unconscious branch of PNS)

- The Endocrine System

Question 10

What activates the fight or flight response?

Answer 10

The hypothalamus when danger is detected

Question 11

Outline the fight or flight response

Answer 11

• Danger is presented + hypothalamus is stimulated
• Hypothalamus activates 2 forms of physiological arousal…
  ANS: Shift from parasympathetic to sympathetic state. This prepares + excited the body for action.
  ENDOCRINE SYSTEM: Pituitary gland produces ACTH to trigger adrenal glands to release adrenaline. Adrenaline arouses body.
• Once danger removed, parasympathetic nervous system activated to calm the body (return to rest + digest)

Question 12

How do the effects of adrenaline help the fight or flight response?

Answer 12

• Increased heart rate: more blood flow provides brain + muscles with more glucose to run or fight
• Increased breathing rate: more oxygen for brain to make quick decisions

Question 13

What is ACTH?

Answer 13

Short term stress hormone

- Triggers adrenal glands in the fight or flight response

Question 14

Give one negative evaluation point for the fight or flight response

Answer 14

May only apply to men

• Taylor et al said it only applies to men + women have evolved a different response based on role as primary caregivers
• Women TEND (use nurturing behaviours to protect themselves + their offspring) + BEFRIEND (form protective alliance with other females against the danger)
• Experiments using females rats supported this (oxytocin hormone released - de-stressor, prohibiting fight or flight)
• So, evidence supports that women have a different response to danger

Question 15

Give one positive evaluation point for the fight or flight response

Answer 15

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