5.4 Flashcards
what are examples of exocrine glands
-pancreas
-salivary glands
-liver
-stomach
what are examples of endocrine glands
-pituitary gland
-thyroid gland
-adrenal gland
-islets of Langerhans in pancreas
-ovaries
-testes
what does the salivary gland secrete
secretes saliva
what does the pituitary gland secrete
secretes many hormones (e.g ADH)
what does the thyroid gland secrete
secretes parathyroid, secretes
what does the adrenal glands secrete
release adrenaline and a number of of other hormones known as corticoids
what does the islets of Langerhans in the Pancreas secrete
secretes insulin and glucagon which goes into the blood
what do the ovaries secrete
secrets oestrogen and progesterone
what do the testes secrete
secretes testosterone
what does the pancreas secrete
secretes pancreatic juice
what does the stomach secrete
secretes gastric juice
what does the liver secrete
secretes bile
what are the 2 types of gland
endocrine and exocrine
what are endocrine glands
endocrine glands secrete hormones directly into the bloodstream
what are exocrine glands
secrete hormones into a duct (tube) which carries the hormone to a specific part of the body e.g. salivary gland
why will hormones only affect certain target cells/tissue
the target cells/ tissues will have the specific receptor for the hormone
define the endocrine system
a communication system which uses hormones as signalling molecules
uses blood as the circulatory system to transport its molecules
what are hormones
Hormones are molecules (proteins or steroids) that are released by endocrine glands directly into the blood.
They act as messengers, carrying a signal from the endocrine gland to a specifc target organ or tissue.
What are the two types of Hormones?
- Protein and Peptide Hormones
(Adrenaline, Insulin, and Glucagon) - Steroid Hormones
(Oestrogen and Testosterone)
How do Protein and Peptide Hormones work?
Proteins are insoluble in the phospholipid membrane and do not enter the cell.
Protein hormones need to bind to the cell surface membrane and release and second messager inside the cell
How do Steroid Hormones work?
Steroid hormones are soluble in the phospholipid membrane and enter the cell and the nucleus, to have a direct effect on the DNA in the nucleus.
What are Target cells?
For non-steroid hormones
Target cells possess a specific receptor on their plasma membrane.
The shape of the receptor is complementary to the shape of the Non-Steroid Hormone molecule.
What are Endocrine glands?
Endocrine glands release hormones directly into the blood.
They are ductless and consist of cells that manufacture the hormone and then secrete it into capillaries running through the gland
What are Exocrine glands?
Exocrine glands do not secrete hormones, but usually enzymes.
They consist of cells surrounding a small duct which then leads to the site where the secretion is needed.
Why are Non-Steroid hormones known as First Messengers?
Non-steroid hormones cannot pass through the plasma membrane.
They are signalling molecules outside the cell that bind to the cell surface membrane and initiate an effect inside the cell.
It is often the release of another signalling molecule inside the cell, which is called the Second Messenger.
What are Second Messengers?
The Second Messenger stimulates a change in the activity of the cell.
What are the Steps of Action of Non-Steroid Hormones (adrenaline)?
- The Non-steroid hormone binds to a complementary receptor on a cell surface membrane. It is the first messenger.
- The G-Protein on the inside of a membrane is activated when the hormone binds.
- The G-protein in turn activates an effector molecule. This is usually an enzyme that converts an inactive molecule into an active second messenger.
In many cells, the effector molecule is the enzyme Adenyl Cyclase, which converts ATP to cyclic AMP (cAMP).
- The second messenger is cAMP which may act directly on another protein (such as an Ion channel), or it may initiate a cascade of enzyme-controlled reactions that alter the activity of the cell.
where is adrenaline secreted from
from the adrenal glands (adrenal medulla)
when is adrenaline sectreted
during fight or flight
is adrenaline a peptide or steroid hormone
peptide hormone
where are the receptors that adrenaline binds to
receptors on the cell surface membrane
detail of adrenaline
detail of adrenaline
detail of adrenaline
detail of adrenaline
Where are the Adrenal glands located?
The Adrenal glands are found anterior/ just above the kidneys. There is one on each side of the body.
What are the two main regions the Adrenal gland is divided into?
Each Adrenal gland is divided into the Outer Adrenal Cortex and the inner Adrenal Medulla
Both regions are well supplied with blood vessels and produce hormones that are secreted directly into the blood vessels.
which hormones are secreted by the adrenal medulla
adrenaline and noradrenaline
are the adrenal glands endocrine or exocrine, how do you know
endocrine (blood secreted into blood)
both regions of the gland are well supplied with blood vessels
What are the three regions of the Adrenal Cortext in between the capsule and the medulla?
- Zona Glomerulosa (Outer)
- Zona Fasciclulata (Middle)
- Zona Reticularis (Inner)
How does the Adrenal Cortex synthesise its Hormones?
The Adrenal Cortex uses Cholesterol to produce Hormones.
These hormones are steroid based and so are able to enter cells directly by dissolving into the cell surface membrane and having a direct effect in the DNA to cause Protein Synthesis.
What are the steps for the Action of Steroid Hormones?
- The steroid hormone passes through the cell membrane of the target cell.
- The steroid hormone binds with a specific receptor in the cytoplasm.
- the receptor-steroid hormone complex enters the nucleus of f the target cell and binds to another specific receptor on the chromosomal material
- Binding stimulates the production of mRNA molecules, which code for the production of proteins
What is the Zona Glomerulosa and what does it secrete ?
The Zona Glomerulosa is the outermost layer, which secretes Mineralocorticoids such as Aldosterone.
What is the role of Mineralocorticoids secreted from the Zona Glomerulosa?
-Mineralocorticoids control the concentration of Sodium and Potassium ions within the blood
- Maintain blood pressure