Chapter 5.2 Flashcards
What is a direct hormone?
A direct hormone is a hormone that is secreted and then acts directly on the target tissue.
What is a tropic hormone?
A tropic hormone is a hormone that acts on a different endocrine gland to cause it to release or withold its hormones. (Ex. GnRH is released which causes release of LH which causes increase in testosterone/estrogen which then has functions)
Where are tropic hormones usually created?
In the brain. It makes sense because the brain is the central control center for the body, and tropic hormones play a overall regulatory role.
What suffixes are usually associated with peptide or amino acide derivative hormones?
-in or ine
Examples: Insulin, vasopressin, thyroxine, epinephrine, etc.
What suffixes are usually associated with steroid hormones?
-one, -ol, or -oid
Ex. Testosterone, aldosterone, mineralcorticoids, cortisol, estradiol, etc.
List the major endocrine organs/glands in the human body
- Pineal Gland
- Pituitary Gland
- Pancreas
- Parathyroid Glands
- Hypothalamus
- Adrenal Glands
- Testes
- Thyroid Glands
- Ovaries
What is the hypothalamus and what is its function in the endocrine system?
The hypothalamus is a structure in the brain that controls the pituitary and affects the various levels of hormones it produces.
How does the hypothalamus exert its effects on the pituitary? What type of signaling?
The hypothalamus affects the pituitary by releasing hormones that travel through a portal system to affect the pituitary. This is an example of paracrine signalling.
What is a portal system?
Usually in the body, each tissue has its own capillary bed that branches off from a main artery. Portal systems are exceptions to this rule. In a portal system, two capillary beds that are associated with different tissues/organs are connected in series. So, instead of an artery independently supplying the two capillary beds, the artery supplies one capillary bed and the blood flows through that capillary bed into the next one before connecting back to a vein.
What is negative feedback?
Negative feedback is when a hormone or product inhibits enzymes and hormones earlier in the chemical pathway to create that hormone or product. This means that, as the levels of hormone or product rise, the amount of that hormone or product that is being produce falls.
What are the 5 hypothalmic hormones? tropic or direct?
- Gonadotropin-Releasing Hormone (GnRH)
- Growth Hormone Releasing Hormone (GHRH)
- Prolactin-inhibiting factor (dopamine)
- Thyroide Releasing Hormone (TRH)
- Corticotropin Releasing Hormone (CRH)
Tropic except dopamine
What is the route taken by hypothalmic hormones after they are secreted?
Hypothalmic hormones travel directly through the capillary beds of the hypothalamus to the capillary beds of the anterior pituitary due to the portal system that connects them.
The 4 tropic hypothalmic hormones are all subject to _______
negative feedback
What is an axis in the context of the endocrine system?
Axis is the term used to refer to the common three-organ pathways the endocrine system takes to exert its effects. For example, the HPA axis refers to the communication between the Hypothalamus, the Anterior Pituitary, and the Adrenal glands. The HPO Axis refers to the communication between the Hypothalamus, the Anterior Pituitary, and the Ovaries.
What effect does GnRH have?
GnRH stimulates the anterior pituitary to release FSH and LH.
What effect does TRH have?
TRH stimulates the anterior pituitary to release TSH (Thyroid Stimulating Hormone).
What effect does CRF have?
CRF stimulates the anterior pituitary to release ACTH (Adrenocorticotropic hormone).
What effect does Dopamine have?
Dopamine inhibits the anterior pituitary from releasing Prolactin. Dopamine also has various effects on motivation/feelings of accomplishment/happiness
What would happen if you removed all the receptors for a hormone from cells?
Then the hormone would have no effect. Remember, hormones need to bind to receptors to exert their effects.
What two hormones does the posterior pituitary release?
- Oxytocin
- Antidiuretic Hormone (ADH or Vasopressin)
What are the 3 functions of Oxytocin?
- Stimulate uterine contractions during child labor
- Stimulate milk ejection due to baby latching
- Stimulate the formation of emotional bonds
What is the function of Antiduretic hormone (ADH)?
ADH increases re-absorption of water in the collecting ducts of the kidneys in response to increased plasma osmolarity or increased concentration of solutes in blood or low blood volume. This increases blood volume and decreases osmolarity
What are the two divisions of the pituitary?
Anterior and Posterior
What are the 7 hormones of the Anterior Pituitary?
- Follicle Stimulating Hormone (FSH)
- Luteinizing Hormone (LH)
- Adrenocorticotropic Hormone (ACTH)
- Thyroid Stimulating Hormone (TSH)
- Prolactin
- Endorphins
- Growth Hormones
MNEMONIC: FLAT PEG of note, the FLAT hormones are tropic and the PEG hormones are direct.
What is the function of Prolactin?
Prolactin stimulates the production of milk in the mammary glands.
What is the function of Endorphins?
Endorphins decrease the perception of pain and cause feelings of euophoria.
What is the function of Growth Hormone and how does it carry this out?
Growth hormone promotes the growth of bone and muscle. stimulates breakdown of fatty acids and prevents glucose uptake in tissues not growing, thus increasing glucose availability for tissues that are growing
What happens if you have excess Growth Hormone as an adult?
Your long bones only grow for a defined section of time, after which they will stop growing. If you take Growth Hormone after this period of time passes, various small bones in your hands, feet, and head will grow, but the long bones in your arms, legs, chest, etc. will not.
What is a positive feedback loop?
Positive feedback loops are when the product of a reaction stimulates its own production. This means the more of the product you have, the faster more if it is produced.
Ex. oxytocin induces uterine contraction which induces more oxy which induces stronger contraction etc.
Which pituitary hormone undergoes positive feedback?
Oxytocin. During birth, oxytocin stimulates the contraction of the uterus, and then contractions of the uterus stimulate oxytocin release. This means the contractions quickly get stronger and stronger, which is a good thing in the case of birth.
