A&P 2 Endocrine System
Describe the locations of and the anatomical relationships between the hypothalamus
- Neuroendocrine organ located within diencephalon of brain and connected to pituitary gland stalk called infundibulum.
Describe the three stages of the stress response
1. Immediate response: Sympathetic nervous system is activated. Fight or flight response. 2. Short-term stress response: Adrenal medulla is activated by a neural stimulus. Epinephrine and norepinephrine are secreted. A sympathetic response is prolonged. 3. Long-term stress response: Adrenal cortex is activated by a hormonal stimulus, cortisol is secreted, continues short-term stress response.
Explain the role of the hypothalamus in the production and release of posterior pituitary hormones
Action potentials travel down the axons of hypothalamic neurons, causing hormone release from their axon terminals in the posterior pituitary.
cellular effect
Activates second-messenger systems
List the major chemical classes of hormones found in the human body that is Water soluble
Amino acid hormones (proteins, peptides, amino-acid)
Describe the roles of negative and positive feedback in controlling hormone release
Blood levels of hormones are mainly controlled by negative feedback which maintains the body on a regulatory levels and positive feedback increases which increases the levels.
Transport in blood
Does not require carrier molecule
What are the hormones associated?
Estrogen, progesterone, testosterone, cortisol, aldosterone, androgens, calcitrol, thyroid hormone.
Provide specific examples to demonstrate how the endocrine organs respond to maintain homeostasis in the body
For example, blood glucose regulation is controlled by insulin and glucagon, hormones produced by the pancreas. Secretion of melatonin from the pineal gland.
Receptor location
Intracellular Receptors
Describe the Renin-Angiotensin-Aldosterone mechanism
Is a hormone system within the body that is essential for the regulation of blood pressure and fluid balance. The system is mainly comprised of the three hormones renin, angiotensin II and aldosterone. Primarily it is regulated by the rate of renal blood flow.
what are the hormones associated?
Norepinephrine/Epinephrine Melatonin Oxytocin
Define the terms paracrine and autocrine
Paracrine: locally acting chemicals that affect cells other than those that secrete them. Autocrine: Chemicals that exert effects on same cells that secrete them.
Describe how each class is transported in the blood
Requires carrier molecules
List the major chemical classes of hormones found in the human body that is lipid soluble
Steroids and Thyroid Hormones
Explain how the endocrine organs relate to other body organs and systems to maintain homeostasis
The endocrine system is regulated by negative feedback mechanisms that work to maintain homeostasis. The concentration of hormones, and how they effect other body systems, are controlled in this manner.
List the hormones released during short-term stress and describe the hormonal actions
The hormones epinephrine (also known as adrenaline) and norepinephrine (also known as noradrenaline) are released by the adrenal medulla.
Receptor location
Transmembrane receptors
Explain the role of the hypothalamus in the release of anterior pituitary hormones
When stimulated hypothalamic neurons secrete releasing or inhibiting hormones into the primary capillary plexus. Hypothermic hormones travel through portal veins to the anterior pituitary where they stimulate or inhibit releases of hormones made in the anterior pituitary. In response to releasing hormones the anterior pituitary secretes hormones into the secondary capillary plexus. *Hypothalamic hormones released into special blood vessels the (portal system) control the releases of anterior pituitary hormones,
Define the terms endocrine gland, hormone, and target cell
- Endocrine Gland secrete hormones and it is located throughout the body. - Hormones are chemicals released into the blood and transported throughout the body. - Target calls contain specific receptors for hormones, initiate or inhibit selective cellular metabolic activities.
List and describe several types of stimuli that control production and secretion of hormones
- Humoral stimulus: hormone release caused by altered levels of certain critical ions or nutrients. - Hormonal stimulus: Hormone release caused by another hormone (tropic hormone) - Neural stimulus: Hormone release caused by neural input.
List the major hormones released during long-term stress and describe the hormonal actions
- In a long-term stress response, the hypothalamus triggers the release of ACTH from the anterior pituitary gland. - Corticosteroids - Cortisol - Glucocorticoids
Describe the locations of and the anatomical relationships posterior pituitary glands aka neurohypophysis
- Maintains neural connections to hypothalamus via hypothalamic-hypophyseal tract. - Neuron cell bodies located in hypothalamus synthesize posterior pituitary hormones - Posterior pituitary is composed of neuronal axon terminals that secrete hormones
Define the terms releasing hormone, inhibiting hormone and tropic hormone
- Releasing hormone: A hormone that stimulates the secretory action of an endocrine gland. - Inhibiting hormone: A hormone that inhibits the secretory action of an endocrine gland. - Tropic hormone: A hormone that regulates the secretory action of another endocrine organ.
Describe the locations of and the anatomical relationships of anterior pituitary aka adenhypophysis
- composed of glandular tissue that synthesizes and secretes its own hormones. - Vascularly connected to hypothalamus via hypophyseal portal system consisting of: primary capillary plexus, hypophyseal portal veins, secondary capillary plexus.
Describe the synthesis, transport, and regulation of thyroid hormone
Thyroid hormone (TH) synthesis and release is under feedback regulation by the hypothalamic input to the pituitary via thyroid-stimulating hormone (TSH) and thyroid-releasing hormone (TRH) resulting in pituitary secretion of TSH.
