The Endocrine System

This section explains the endocrine system including the major endocrine glands and their functions. It also explains Controlling Blood Glucose Concentration and Diabetes. 

Structure and Function

The endocrine system is a network of glands that produce and release hormones to regulate various bodily functions. Unlike the nervous system, which uses electrical signals, the endocrine system relies on chemical messengers (hormones) transported in the blood to target organs. It plays a key role in growth, metabolism, reproduction, and homeostasis.

Image

Major Endocrine Glands and Their Functions

Pituitary Gland – Known as the 'master gland', it is located at the base of the brain and releases several hormones, including:

• Growth hormone (stimulates growth and development)
• Anti-diuretic hormone (ADH) (controls water balance in the body)
• Follicle-stimulating hormone (FSH) and Luteinising hormone (LH) (involved in reproduction)

Pancreas – Regulates blood glucose levels by producing:

• Insulin (lowers blood glucose levels by promoting glucose uptake into cells)
• Glucagon (raises blood glucose levels by stimulating the conversion of glycogen to glucose in the liver)

Thyroid Gland – Found in the neck, it produces thyroxine, which controls metabolic rate, heart rate, and temperature regulation.

Adrenal Glands – Located above each kidney, they release adrenaline, which prepares the body for 'fight or flight' responses by increasing heart rate and redirecting blood to muscles.

Ovaries (Females) – Produce oestrogen and progesterone, which regulate the menstrual cycle and pregnancy.

Testes (Males) – Produce testosterone, which controls sperm production and secondary sexual characteristics such as increased muscle mass and body hair.

Controlling Blood Glucose Concentration

Blood glucose levels must be maintained within a narrow range for proper cell function. The pancreas plays a crucial role in this regulation:

When blood glucose is too high:

• The pancreas releases insulin.
• Insulin stimulates cells, especially in the liver and muscles, to absorb glucose and store it as glycogen.
• This lowers blood glucose levels back to normal.

When blood glucose is too low:

• The pancreas releases glucagon.
• Glucagon signals the liver to break down glycogen into glucose and release it into the bloodstream.
• This raises blood glucose levels back to normal.

Diabetes

Diabetes is a condition where blood glucose regulation is impaired due to insufficient insulin production or ineffective insulin response.

Type 1 Diabetes:

• The immune system attacks insulin-producing cells in the pancreas.
• Patients require insulin injections to regulate blood sugar levels.
• Managed through insulin therapy, diet control, and exercise.

Type 2 Diabetes:

• The body becomes resistant to insulin or does not produce enough insulin.
• Linked to obesity, poor diet, and lack of exercise.
• Managed through lifestyle changes, medication, and sometimes insulin therapy.

Understanding the endocrine system is crucial in biology as it highlights the body's ability to maintain homeostasis and adapt to changing conditions through hormonal control.