Metabolism - 4 Flashcards
Endocrine System
What is the primary aim of the endocrine system?
To maintain a stable and balanced internal environment (homeostasis)
T/F: the nervous and endocrine system act together to coordinate and regulate all systems of the body
True
T/F: the nervous system releases neurotransmitters and has slow responses
False, has fast responses
The endocrine system releases hormones, do they act slow or fast?
Slow, they going into the blood stream or the interstitial fluid and have to travel around the body
Definition:
Exocrine glands
Secrete the products they produce into ducts, which are then expelled on the outside of the body
Do exocrine glands secrete hormones?
No
What are some examples of exocrine glands?
- sudoriferous (sweat) glands
- sebaceous (oil) glands
- muscous glands
- digestive glands
What is the difference between signals sent in the nervous system vs the endocrin system?
Nervous - send neurotransmitters
Endrocrine - send hormones
What are hormones released into?
The bloodstream
What do hormones determine?
- the devlopment of sexual characteristics in puberty
- regulate how the body grows and develops
- how the body controls fluid, salt and sugar levels in the blood
Definition:
Hormones that travel in blood and act on distant target cells
Endocrines (circulating hormones)
Definition:
Paracrines
Hormones that act on neighboring cells
Definition:
Hormones that act on the same cell that secreted them
Autocrines
Hormones can be —- soluble or —- soluble?
Water or lipid
Examples of lipid soluble hormones
- steroid hormones
- thyroid hormones
- nitric oxide
How do lipid soluble hormones work?
- circulate bound to trasnport proteins
- diffuse across the plasma membrane
- bind to receptors within target cells
- activate genes to allow ribosomes to synthesize specific proteins (goes into nucleus)
Examples of water-soluble hormones
- amine hormones
- peptide and protein hormones
- eicosanoid hormones
How do water soluble hormones work?
- circulate freely in plasma
- bind to recpetors on the xterior surface of the target cell
- activate a secondary messenger to phosphorylate cellular proteins
Phosphorylation can either:
- activate (excitatory) –> results in the production of proteins through a chain reaction
- inactivate (inhibitory)
T/F: hormone regulation can also be controlled through alterations to the receptors themselves
True
Definition:
Up-regulation
Receptors become more sensitive (more receptors) in the presence of low concentrations of hormone
Definition:
Receptors become less sensitive (less receptors) in the presence of high concentrations of hormone
Down-regulation
What is the response of a target cell to a hormone based on?
- hormones concentration in the blood
- number of hormone receptors on the target cell
- influences exerted by other hormones
Definition
Synergistic effect
Some hormones work more effectively when a second hormone is present to assist them
Definition
Antagonistic effect
some hormones oppose the action of others
Go over norepinepherine responses (slide 20)
Why are hormones released in short bursts?
To maintain homeostasis and prevent over or underproduction of a particular hormone
What is hormone secretion regulated by?
- Chemical changes in the blood
- signals from the nervous system
- other hromones
T/F: most endocrine glands are under positive feedback control that acts to maintain homeostasis
False, negative feedback loops
What is the major regulatory role of the hypothalamus?
Regulates homeostasis for body temperature, blood glucose levels and osmotic pressure
T/F: the hypothalamus is the main link between the endocrine and the nervous system
true
How many hormones does the hypothalamus release?
7
Hormones released from the hypothalamus instruct which gland to release certain hormones?
The pituitary gland
List the releasing hormones of the hypothalamus.
- thyrotropin releasing hormone (TRH)
- corticotropin releasing hormone (CRH)
- gonadotropin releasing hormone (GnRH)
- Prolactin releasing hormone (PRH)
- growth hormone releasing hormone (GHRH) – somatocrinin
List the inhibiting hormones of the hypothalamus.
- growth hormone inhibiting hormone (GHIH) – somatostatin
- prolactin inhibiting hormone (PIH) – dopamine
What connects the hypothalamus and the pituitary gland?
Infundibulum (stalk)
How do the hormones released by the hypothalamus reach the pituitary gland?
Via the hypophyseal portal system (circulation from hypothalamus goes directly to pituitary gland, so it does not enter systemic circulation)
What part of the pituitary gland makes up 75% of its weight?
The anterior Lobe (adenohypophysis)
How many types of cells are located in the anterior pituitary gland and how many hormones do they secrete?
cells - 5
hormones - 7
What are the 7 hormones released by the anterior pituitary gland?
- human growth hormone (hGH)
- Prolactin (PRL)
- Thyroid-stimulating hormone (TSH)
- Follicle stimulating hormone (FSH)
- Luteinizing hormone (LH)
- andrenocoticotrophic hormone (ACTH)
- melanocyte-stimulating hormone (MSH)
What cells secrete hGH?
somatrophs
What cells secrete PRL?
lactrotrophs
What cells secrete TSH?
Thyrotrophs
What cells secrete FSH and LH?
Gonadotrophs
What cells secrete ACTH and MSH?
Corticotrophs
What is the most plentiful anterior pituitary hormone that aids with the growth of bones and muscles?
Human growth hormone (hGH)
What 2 hypothalamic hormones control the release of hGH?
- GHRH
- GHIH
Definition:
Stimulates the production of thyroid hormones from the thyroid gland activities and is controlled by TRH (thyrotropin relaeasing hormone)
TSH (thyroid stimulating hormone)
Definition:
PRL
With other hormones, initiates and maintaines milk secretion by the mammary glands
What does FSH do in females?
initiates follicle development and secretion of estrogens in ovaries
What does FSH do in males?
Stimulates sperm production in the testes
Definition:
Controls the production and secretiopn of hormones called glucocorticoids by the cortext of the adrenal gland.
ACTH (adrenocorticotrophic hormone)
What is the posterior lobe (neurohypophysis) of the pituitary gland made of?
Neural tissue
Which is more vascularized, anterior or posterior pituitary gland?
anterior
T/F: posterior pituitary gland synthesizes hormones
false! It only stores and relases 2 hormones that are synthesized in the hypothalamus
What 2 hormones are stored in the posterior pituitary gland?
Oxytocin and ADH (anti-diruetic hormone)
Definition:
Released in repsonse to stretch placed on the cervix during child birth
Oxytocin
Does oxytocin work through a + or - feedback loop?
Positive!
What does oxytocin affect?
- uterus: enhances contractions
- breasts: stimulates milk production by the mammary glands in response to suckling
- males: aids in the dopamin-oxytocin-nitric oxide pathway for erections
What does the amount of ADH produced vary with?
Blood osmotic pressure
Explain how ADH works.
ADH decreases urin output as part of a - feedback loop where osmoreceptors in the hypothalamus monitor blood osmotic pressure
An increase in blood volume cause a ____ in ADH secretion.
decrease
An decrease in blood volume cause a ____ in ADH secretion.
increase
