A&P Chapter 17 Endocrine System Flashcards
Describe the Endocrine System, how does it affect the bodies tissues/cells?
The Endocrine system is comprised of ISOLATED organs and tissues which secrete chemical messengers (hormones) into the BLOOD which causes changes in cells and tissues (TARGETS) elsewhere in the body.
All cells are exposed to hormones but not all cells are affected by them, they MUST HAVE RECEPTOR SITES FOR A PARTICULAR HORMONE TO BE AFFECTED, THEY MUST BE A TARGET.
Explain how Endocrine glands communicate with cells/tissues.
Endocrine glands are DUCTLESS so they must secrete their hormones into rich networks of capillaries which then carry the hormone quickly through the blood to target cells/tissues.
What are the three major chemical groups of the Endocrine System?
Peptides, Amines and Steroids.
Describe Peptides:
They are chains/rings of Amino Acids. Peptides are smaller than proteins. They have DISULFIED bonds affecting their 3-D shape (conformation)
Insulin, Oxytocin, and Antidiuretic Hormone are examples of Peptides.
Describe Amines:
They are SMALL molecules containing one or more amine group. An Amine group will be NH IF it’s followed by a Carbon group or NH2 if it is not.
Epinephrine, Norepinephrine and Dopamine are all examples of Amines.
Describe Steroids:
Steroids are formed from the lipid cholesterol by adding specific side chains.
Progesterone, Estradiol, Cortisol and Aldosterone are examples of Steroids.
Explain how the Nervous system and the Endocrine system are similar but different.
The nervous system uses Hormones for Neurotransmitters, they are released into the synaptic cleft and affect a target cell or neuron. This activation/stimulation happens in a fraction of a second and can be controlled VERY precisely, it’s effect however is not very long lasting. The nervous system can be VERY targeted and affect a very precise area or cells.
The endocrine system secretes hormones into the blood stream where it is distributed throughout the body, it’s effects can last over a much longer period of time and can affect large areas of the body. It is not as fast acting as the Nervous system and it is not always as precise with regards to it’s ability to target specific cells/tissues.
The nervous system and endocrine system work together in some situations, the nervous system can begin affecting a target cell/tissue quickly while the endocrine system is preparing to affect the same cell/tissue over a longer period of time.
What changes can hormones produce?
They can stimulate or inhibit cell differentiation, cell division, protein synthesis and secretion. They can also activate or deactivate enzymes. They can also change the permeability of the plasma membrane.
What are the three types of receptors?
Transmembrane proteins: They travel all the way through the plasma membrane.
Glycoproteins: Carbohydrates attached to proteins in the plasma membrane.
Glycolipids: Carbohydrates attached to Lipids in the plasma membrane.
How can the effect of a hormone on a target cell be increased or decreased?
- Changing the amount of Hormone in the bloodstream.
- Changing the # of receptors which the target cells have for the hormone.
- Changing the specificity and affinity which these receptors have for the hormone.
Describe UPREGULATION:
When a cell adds more receptors to it’s plasma membrane in response to fewer hormone circulating in the blood stream to maintain the same affect on the cell.
Describe DOWNREGULATION:
When a cell removes receptors from it’s plasma membrane in response to an increase in a hormone circulating in the blood stream to maintain the same effect on the cell.
What are the MAJOR Endocrine hormones?
Hypothalamus, Pituitary gland, Pineal gland, Thyroid gland, Parathyroid glands, Thymus gland, Adrenal glands, Pancreas and the Gonads (Ovaries and Testes)
Describe the Pituitary Gland
It’s also known as the Hypophysis. It’s located in the Sella Turcica of the Sphenoid bone. It has two developmentally AND functionally different parts both of which are under direct control from the Hypothalamus.
There is an ANTERIOR Pituitary (Adenohypophysis) gland and a POSTERIOR Pituitary Neurohypophysis gland.
The anterior pituitary is controlled by a portal system of capillaries while the posterior secretes hormones that arise as neurotransmitter from neurons originating in the Hypothalamus.
Describe the Anterior Pituitary Gland
Also called the Adenohypophysis. It did not originate as a part of the brain as the Posterior Pituitary did.
It is regulated by a portal system from the Hypothalamus, RELEASING FACTORS secreted from the hypothalamus travel through capillaries in the hypothalamus to capillaries in the Anterior pituitary gland causing a release of hormones by the Ant. pituitary.
It secretes 6 PEPTIDE hormones.
What is the portal system between the Hypothalamus and the Anterior Pituitary called?
The Hypothalamic-Hypophyseal Portal Vein.
What are the 6 Peptides secreted by the Anterior Pituitary gland?
Growth Hormone (GH) Thyroid Stimulating Hormone (TSH) Adrenocorticotropic Hormone (ACTH) Prolactin (PRL) Follicle Stimulating Hormone (FSH) Luteinizing Hormone (LH)
What is the major function of Growth Hormone (GH)?
Stimulates the growth of many organs.
What is the major function of Thyroid Stimulating Hormone (TSH)?
Stimulates the Thyroid Gland to secrete its hormones.
What is the major function of Adrenocorticotropic Hormone (ACTH)?
Stimulates the adrenal cortex to secrete its hormones.
What is the major function of Prolactin (PRL)?
Stimulates the production of milk by mammary glands.
What is the major function of Follicle Stimulating Hormone (FSH)?
Stimulates the development of egg/sperm.