Endocrine System Overview Quiz

Study Notes

Endocrine System Overview

The endocrine system comprises glands and tissues secreting hormones, which are chemicals influencing other glands/tissues.
Endocrine glands lack ducts, releasing hormones directly into tissue fluid.
The endocrine system, like the nervous system, participates in homeostasis.
Endocrine hormones travel via blood, causing slower but often longer-lasting responses compared to the nervous system.
Hormone production is regulated by negative feedback and antagonistic hormones.

Hormone Action

Hormones are chemical signals, communicating between cells, body parts, or even individuals.
Two main hormone categories exist:
- Peptide hormones: These comprise peptides, proteins, glycoproteins, or modified amino acids.
- Steroid hormones: These have a common four-carbon ring structure but differ in side chains.

Pheromones

Pheromones are chemical signals influencing the behavior of individuals within the same species.

Hypothalamus and Pituitary Gland

The hypothalamus regulates internal environment through the autonomic nervous system (e.g., heart rate, blood pressure).
It also modulates gland secretions, including those of the pituitary gland.
Posterior pituitary: Stores and releases hormones (ADH and oxytocin) produced by the hypothalamus.
- ADH (antidiuretic hormone) increases water reabsorption in kidneys when blood is concentrated.
- Oxytocin stimulates uterine contractions during childbirth and milk release during breastfeeding (positive feedback).
Anterior pituitary: Controlled by hypothalamic-releasing and inhibiting hormones, which in turn stimulate the anterior pituitary to produce hormones like:
- Thyroid-stimulating hormone
- Adrenocorticotropic hormone
- Gonadotropic hormones
- Prolactin
- Melanocyte-stimulating hormone
- Growth hormone

Thyroid and Parathyroid Glands

Thyroid gland: Located in the neck; produces hormones affecting metabolic rate and blood calcium levels.
Parathyroid glands: Embedded in the thyroid; release parathyroid hormone, which decreases blood phosphate and increases blood calcium levels.

Adrenal Glands

Adrenal glands: Located atop the kidneys.
Adrenal medulla: Produces epinephrine and norepinephrine, rapidly responding to stress.
Adrenal cortex: Releases hormones for longer-term stress responses.
- Glucocorticoids (e.g., cortisol): Increase blood glucose and counteract inflammation.
- Mineralocorticoids (e.g., aldosterone): Regulates blood volume and blood pressure by targeting the kidneys.

Pancreas

Pancreas has exocrine tissue (secretes digestive juices) and endocrine islets (produce hormones).
Pancreatic islets: Secrete insulin and glucagon (blood sugar regulation) and somatostatin (growth hormone inhibitor).

Other Endocrine Glands

Gonads: Produce sex hormones.
- Testes (males): Produce sperm and androgens (e.g., testosterone).
- Ovaries (females): Produce eggs and female sex hormones (e.g., estrogen, progesterone).
- Hypothalamus and pituitary gland control gonadal hormone secretion (puberty and secondary sex characteristics)
Thymus: Secretes thymosins, aiding in T lymphocyte differentiation.
Pineal gland: Produces melatonin, influencing the sleep-wake cycle.

Hormones from Other Tissues

Some organs (not typically considered endocrine glands) still secrete hormones.
- Leptin: Produced by adipose tissue; signals satiety (fullness).
- Growth factors: Produced by various organs and cells.

Description

Test your knowledge on the endocrine system, including the functions and types of hormones, as well as the role of the hypothalamus and pheromones. This quiz covers essential concepts related to hormonal signaling and homeostasis.