10. (a) (i) What term is used for glands that secrete hormones? (ii) How do these glands differ from those that do not secrete hormones? (iii) Explain why the pancreas may be described as a dual-function gland - Leaving Cert Biology - Question 10 - 2013

Endocrine glands differ from exocrine glands in that they are ductless. Unlike exocrine glands, which secrete substances through ducts to specific locations (such as sweat or salivary glands), endocrine glands release hormones directly into the circulatory system, making their effects more systemic.

The pancreas is described as a dual-function gland because it serves both endocrine and exocrine functions. As an endocrine gland, it secretes hormones such as insulin and glucagon, which regulate blood sugar levels. As an exocrine gland, it produces digestive enzymes that are released into the small intestine to aid in digestion.

Many hormones are classified as proteins. They are typically made up of amino acids and function to regulate physiological processes in the body.

1. Insulin

   • Gland Location: Secreted by the pancreas.
   • Function: Regulates blood glucose levels by facilitating cellular uptake of glucose.

2. Thyroxine (T4)

   • Gland Location: Secreted by the thyroid gland.
   • Function: Regulates metabolic rate and influences growth and development.

For insulin:

1. Deficiency symptom: Symptoms of diabetes, such as increased thirst and urination.
2. Excess symptom: Hypoglycemia, or low blood sugar, which can cause dizziness and confusion.
3. Corrective measure: For deficiency, insulin therapy can be administered to help manage blood glucose levels effectively.

Hormonal responses are slower than nervous responses because hormones travel through the bloodstream, which is a slower mode of transport compared to the rapid transmission of electrical signals in the nervous system. Additionally, hormonal processes often require more time to initiate changes in target cells and organs, leading to a gradual rather than immediate response.