Endocrine System Flashcards
What are the endocrine system’s actions mediated by?
Hormones
Which regulatory systems does the endocrine system control?
1- Regulation of cellular metabolism
2- Maintenance of homeostasis
3- Sexual development and reproduction
4- Growth and development from child to adult
5- Modulating long term behaviour such as sleep and mood
What are the two types of glands?
1- Endocrine glands
2- Exocrine glands
What are the main differences between endocrine and exocrine glands?
1- Endocrine glands have no ducts and secrete hormone directly into the blood
2- Exocrine glands contains ducts formed by epithelial cells
What are hormones?
1- Chemical messengers
2- Act on target cells through specific receptors
What are the three classes of hormones?
1- Proteins
2- Steroids
3- Amino acid derivatives
Describe the structure of an exocrine gland.
1- Secretory cells
2- Acinus
3- Basement membrane
4- Duct with lumen
What do salivary glands, sebaceous glands and sweat glands all open onto?
Skin
What does the pancreatic duct open into?
Duodenum
What is paracrine secretion?
1- Cell-to-cell communication
2- Cell secretes factors which induce changes only in adjacent cells
3- Paracrine factors diffuse over short distances
What are paracrine factors made of?
Polypeptides
Why is paracrine secretion relevant/important in embryogenesis?
1- Gradients of polypeptides influence developmental change
What are the four families of paracrine receptors?
1- Fibroblast growth factor (FGF) family
2- Hedgehog family
3- WnT family
4- TGF-β superfamily
What are the ten organs of the endocrine system?
1- Pineal gland 2- Pituitary gland 3- Hypothalamus 4- Thyroid glands 5- Parathyroid glands 6- Thymus 7- Adrenal glands 8- Pancreas 9- Ovaries 10- Testes
How are steroid and thyroid hormones carried in the blood and why?
1- Via specific carrier/binding proteins 2- Improved solubility 3- Increased half-life 4- Provides a reserve in the blood 5- Inactive until freed from carrier
How do hormones act?
By binding onto receptor
Where can hormone receptors be found?
1- Cell membrane receptors
2- Intracellular receptors in the nucleus
What types of hormones bind to cell membrane receptors?
1- Peptides
2- Glycoproteins
3- Catecholamines
What types of hormones bind to intracellular receptors in the nucleus?
1- Steroids
2- Thyroid hormones
hat are steroid hormones synthesised from?
Cholesterol
What are amino acid derived hormones?
1- Thyroid hormones
2- E.g. catecholamines such as adrenalin, dopamine and noradrenaline
What does the anterior pituitary develop from?
Epithelium of mouth
What does the posterior pituitary develop from?
1- Downgrowth of the hypothalamus
2- Consists of nerve fibres
What is the main endocrine axis/regulation?
1- Hypothalamus stimulates pituitary gland
2- Pituitary gland stimulates other distant endocrine organs
Why are target tissues of one hormone another endocrine gland? (What does this allow?)
Allows for amplification and fine control
What is the role of the hypothalamus?
1- Stimulates and controls the secretion and release of pituitary hormones
2- Releases hormones to control release of anterior pituitary hormones
3- Secretes hormones which are stored and released by posterior lobe of posterior pituitary gland
What is the role of pituitary hormones?
1- Stimulated by pituitary hormones
2- Stimulate and control other endocrine glands
How does the hypothalamus control the anterior pituitary gland?
1- Releases hormones which stimulate anterior pituitary gland
2- E.g. prolactin release is controlled by hypothalamic inhibiting factor
What hormones does the posterior lobe of the pituitary gland store and release?
1- Oxytocin
2- Antidiuretic hormone (ADH) (also called Vasopressin)
What six hormones does the anterior pituitary gland secrete?
1- Growth hormone (GH) 2- Thyroid stimulating hormone (TSH) 3- Adrenocortitropic hormone (ACTH) 4- Follicle stimulating hormone (FSH) 5- Luteinising hormone (LH) 6- Prolactin
What does the growth hormone affect?
Stimulates growth of body by increasing levels of glucose free fatty acids to increase cell division
What is TSH’s target organ?
Thyroid