LECTURE 26 - ENDOCRINE SYSTEM Flashcards
Where are hormones released
hormones are released into interstitial fluid then get into blood
Do endocrine cells have ducts
no
Not all fluid/hormones are taken up by blood supply … where does the rest of the hormones go
the remaining hormones are taken up by the lymphatic system
Name the 5 endocrine glands
- Pituitary gland
- Thyroid gland
- Parathyroid gland
- Suprarenal gland
- Pineal gland
Define: Hormones
Hormones: molecules that alter physiological activity of other cells in the body, affects only the target cell
What are the 2 classifications of hormones?
1) Steroid
2) Amino acid
Describe the features of Amino acid derived hormones
Amino Acid Hormones
- majority of hormones
- ex. catecholamines, peptide hormones
- bind the cells membrane bc they can’t enter the cell
- activates second messengers
which type of hormone binds the cell membrane
amino acid derived
Describe the features of Steroid derived hormones
- synthesized from cholesterol
- produced and secreted from gonads and the adrenal gland
- diffuse into target call and bind intracellular receptor which goes into nuclear chromatid and binds DNA
- alters rate of RNA transcription thus altering protein synthesis which can alter other metabolic activities
what classification of hormone is secreted from the adrenal glands
steriod
Where is the hypothalamus located?
Is part of the diencephalon
What’s attached to the hypothalamus
the pituitary gland - is attached to the hypothalamus
What are the 3 functions of the hypothalamus
Hypothalamus Functions =
1) Has direct neural control over endocrine cells of the adrenal medulla (sympathetic output)
2) Production of ADH and oxytocin
3) Secretion of regulatory hormones to control activity of anterior pituitary
Where is the Pituitary Gland located?
The pituitary gland is located in the sella turcia of the sphenoid bon attached to the hypothalamus by the infundibular stalk
What is another name for the pituitary gland?
pituitary gland = hypophysis
Briefly describe the overview of the structure of the pituitary gland?
Pituitary gland:
Anterior lobe
- 75%
- produces and releases 7 hormones
Posterior lobe
- 25%
- ONLY releases
- 2 hormones
Posterior Pituitary:
Makes:
Cells:
Structure:
Neurohormones:
Posterior Pituitary:
Makes: nope only stores and releases
Cells: pituicytes and axon terminals of hypothalamic neurosecretory cells
Structure: pars nervosa and infundibular stalk
Neurohormones: ADH and oxytocin
What are the functions of the neurohormones secreted by the posterior pituitary?
ADH = vasopressin, decrease the water lost thru the kidney
Oxytocin = 1) stims the myometrium to contract
2) stims the release of milk
what is another name for the anterior pituitary?
adenohypophysis
What are the 3 regions of the anterior pituitary?
- pars distalis
- pars intermedia
- pars tuberalis
What 6 hormones does the pars distalis of the anterior pituitary produce/secrete
GH
LH
FSH
ACSH
TSH
PRL
GH (growth hormone)
Produced by:
Purpose:
Growth Hormones - GH
Produced by: somatotrophic cells
Purpose: stims cell growth and replication
Thyroid stimulating hormone TSH
Produced by:
Purpose:
Thyroid stimulating hormone TSH
Produced by: Thyrotropes
Purpose: stims the normal development and secretory activity of the thyroid gland
Follicle-stimulating hormone FSH
Produced by:
Purpose:
Follicle-stimulating hormone FSH
Produced by: gonadotrophs
Purpose: promotes development of the female gametes (oocytes) and stims estrogen secretion via follicular cells
In males promotes sperm production
Luteinizing hormone (LH)
Produced by:
Purpose:
Luteinizing hormone (LH)
Produced by: Gonadotrophic cells
Purpose: stims ovulation and the ovarian production of progesterone
In males: stims androgen production
Prolactin (PRL)
Produced by:
Purpose:
Prolactin (PRL)
Produced by: lactotrophs (prolactin cells)
Purpose: stim development of mammary glands and the production of milk by the mammary glands
Adrenocorticotrophic hormone (ACTH)
Produced by:
Purpose:
Adrenocorticotrophic hormone (ACTH)
Produced by: corticotropic cells
Purpose: stims hormone productions of the adrenal glands
Where and what does the pars tuberalis produce?
- wraps around infundibulum
- contains gonadotropin which helps produce FSH and LH
What does the pars intermedia of the anterior pituitary gland produce?
Melanocyte-stimulating hormone (MSH)
- really active during fetal development and young childhood
- targets melanocytes in skin
Describe blood flow of the hypophyseal portal system
Blood flows from the capillaries -> hypothalamus -> portal veins which carry blood to -> capillaries of the ant pit
Function of hypophyseal portal system?
The hormones carried by this system allow communication btwn the hypothalamus and the ant pit establishing a link btwn the nervous system and the endocrine system
Describe the hypophyseal portal system blood flow into the anterior pituitary?
1) Arterial blood is delivered by branches of the internal carotid artery
2) Internal carotid artery branches into the superior hypophyseal artery
3) The superior hypophyseal artery goes into the infundibulum then divide into the primary capillary plexus
4) before leaving the infundibulum the capillaries merge to make portal vessels which extend down and enter the pars distalis
5) gives rise to the secondary capillary plexus that branches along the endocrine cells
What artery supplies blood to the posterior lobe of the pituitary?
The inferior hypophyseal artery - supplies the posterior pituitary
Describe the drainage of the pituitary gland
From both lobes the blood is drained via the hypophyseal vein and returned to the internal jugular vein
Define - Portal vessels
Portal vessels = bv that connect 2 capillary beds together
what comprises the - Hypophyseal portal system
Hypophyseal portal system = portal veins + 1 and 2 capillary plexus
