(7) THE ENDOCRINE SYSTEM

Question 1

Define the endocrine system

Answer 1

Endocrine system: one of body’s major information systems. Instructs glands to release hormones directly into bloodstream. Hormones are then carried to target organ.

Question 2

What is the endocrine system and what is its function

Answer 2

• What is it?
○ Chemical messenger system
○ Works alongside nervous system to control vital functions in body
○ Controls vital physiological processes
§ Eg growth, metabolism, reproduction, stress response
• Function:
○ Glands and hormones

Question 3

What are the 7 main glands, what hormone do they secrete and what is the function of each hormone

Answer 3

○ 7 main glands:
§ Pituitary
□ Main one, often referred to as “master gland”
□ Where?
® In brain
□ Function?
® Controls release of hormones from all other glands
□ 2 parts:
® Anterior pituitary
◊ ACTH
® Posterior pituitary
◊ Oxytocin and ADH
§ Hypothalamus
□ Hormone:
® Releases hormones
□ Function:
® Links endocrine and nervous system
® Controls pituitary gland
§ Thyroid
□ Hormone:
® Thyroxine (T4)
□ Function:
® Regulates metabolism, temperature, heart rate
§ Adrenal
□ Hormone:
® Adrenaline, cortisol
□ Function:
® Fight or flight response, regulates stress, metabolism, immune response
§ Pancreas
□ Hormone:
® Insulin
□ Function:
® Controls blood sugar levels
§ Ovaries (female)
□ Hormone:
® Oestrogen
® Progesterone
□ Function:
® Regulates menstrual cycle + reproduction
§ Testes (male)
□ Hormone:
® Testosterone
□ Function:
® Regulates sperm production

Question 4

What is the 5 step process of the endocrine system

Answer 4

The process:
1. Hypothalamus
○ Detects change, sends signal to pituitary
2. Pituitary gland
○ Releases hormone (e.g ACTH)
3. Target gland
○ (eg adrenal) releases another hormone (eg cortisol)
4. Target organs
○ Affected by hormone sent out
5. Negative feedback loop
○ Regulates system to maintain balance (homeostasis)

Question 5

What is the 5 step process of the fight or flight response with both the ANS and ES involved

Answer 5

Link with fight or flight:
• Often ANS and ES work in parallel, eg during a stressful event
• Process:
1. Hypothalamus
§ Detects stressor, activates pituitary gland, triggers activity in sympathetic branch of ANS
2. Parasympathetic –> sympathetic
§ ANS state goes from parasympathetic –> sympathetic
3. Adrenaline
§ Released from adrenal medulla (part of adrenal gland) into bloodstream
§ Triggers physiological changes, e.g increased heart rate, creating physiological arousal needed for fight or flight response
4. Immediate and automatic
§ Process happens in an instant
5. Parasympathetic action
§ Once threat has passed, parasympathetic returns to resting state

Question 6

Define gland and hormone

Answer 6

Gland: an organ that synthesises hormones

Hormones: chemical substances that travel via the bloodstream and only affect target organs. Mass produced but quickly used up.

Question 7

Define a fight or flight response and adrenaline

Answer 7

Fight or flight response: how an organism responds when under intense stress

Adrenaline: hormone produced by adrenal glands. Involved in immediate stress response system.

Question 8

Define negative feedback

Answer 8

Negative feedback: a regulatory process where a hormone’s effect triggers a decrease in its own production, helping maintain homeostasis

Question 9

Compare the nervous system and endocrine system

Answer 9

Signal type: ELECTRICAL IMPULSES vs CHEMICAL SIGNALS
Speed: FAST vs SLOW
Duration: SHORT vs LONG
Transmission: VIA NEURONS vs VIA BLOOD