A2/A-level Biology - Endocrine System

• Molecules released by endocrine gland directly into the bladder.
• Acts as a chemical messenger as hormones carry signals form the endocrine gland to specific target cells/tissues.
• E.g. Insulin/glycogen

When it comes to A2/A-level Biology, do you remember the differences between endocrine gland and exocrine gland?

• The endocrine system is another communication system in the body using the blood circulation to transport the signals/materials throughout the body.
• Releases/secretes hormones directly into the blood form the endocrine gland.
• Glands inside the organism which secretes hormones directly into the cell.
• Ductless gland
• It consists of a group of cells that produce/release hormones straight into the blood capillary running through the gland.

• Gland which secretes molecules into a duct hat carries the molecules to where they want to be used.
• E.g. salivary gland

• Cell receives a hormone (signal) which must process a specific complimentary shaped receptor on the plasma membrane.
• Hormones bind to receptors of the target cell.
• Cells in the body process a certain shape which is complimentary, cell then initiates a response.

• An amino acid derivative
• Unable to enter the target cell, therefore causes an affect inside the cell without entering the cell itself.

• Adjacent to the kidney.
• Each gland can be divided into a medulla region and a cortex region.

• Hormone that transmits signals around the body.

• Cyclic adenosine monophosphate

• Hormone that transmit signals inside the cell.

• Enzymes associates with the receptors for many hormones i.e. adrenaline.
• Found in the inside of the cell surface membrane.

• Adrenaline receptors on the outside of the cell surface membrane a shape complimentary to the shape of the adrenaline molecule.
• Enzymes adenly cyclase is associated on the inner surface of the cell surface membrane.
• Adrenaline in the blood binds to a specific receptor on the cell surface membrane. Therefore the adrenaline molecule is a first messenger.
• This activates enzyme adenly cyclase, converting ATP to cAMP, a secondary messenger inside the cell.
• cAMP causes the effector inside the cell by activating enzyme action.

• It is found in the centre of adrenaline gland
• Medulla cells manufacture/release hormone adrenaline in response to stress such as shock, pain.
• It contains adrenaline receptors to prepare the body into action.
  - relaxes smooth muscle
  - increases stroke volume of the heart rate
  - increases heart rate
  - causes vasoconstriction to increase blood pressure
  - stimulates the conversion of glycogen to glucose
  - causes hair erector
  - inhibits action of the gut

• It uses cholesterol to produce steroid hormones.
• Mineralcarticiods (e.g. aldosterone) help to control the concentrateion of Na/K in blood.
• Glucocortiniods (e.g. cortosil) help to control the metabolism of carbohydrates, proteins in the liver.

That's the end of the topic!

CLICK HERE TO LEARN MORE ABOUT OUR A2/A-LEVEL BIOLOGY COURSES

Drafted by Bonnie (Biology)