hormonal communication

What is homeostasis?

Homeostasis is the maintenance of a stable internal environment within an organism

-changes/ deviations are detected by receptors

-effectors bring about responses via negative feedback to bring levels back to normal

What does negative feedback mean

Counteracting a change to bring levels back to normal 

What does the endocrine system consist of and what does it do

Made up of endocrine glands which secret hormones directly into the blood plasma

What are hormones 

Chemical messengers secreted by endocrine glands directly into bloodstream and carried to bind to a specific receptor ON or INSIDE target cells triggering a response in the target cell 

Name 7 endocrine glands

Pituitary gland 

Adrenal gland

Thyroid gland 

Pancreas

Pineal gland 

Ovaries 

Testes 

What is the pituitary gland

Known as the master gland, it releases hormones which stimulate other glands to release other hormones

What is an exocrine gland

secretes chemicals into a duct (a tube that delivers these chemicals e.g. enzymes from one place to another)

What are the 2 types of hormones

Steroid and nonsteroid hormones

What is another name for a nonsteroid hormone

nonsteroid/ peptide hormone

State how nonsteroid hormones work and reason behind it & give an example 

Bind to the specific receptors on the cell surface membrane of target cells to activate secondary messengers

>> they are hydrophobic meaning they cannot diffuse across phospholipid bilayer 

e.g. adrenaline 

State how steroid hormones work and reason behind it & give an example 

Diffuse across cell and bind to receptor molecules in the cytoplasm/ nucleus forming hormone-receptor complex 

>> they are hydrophilic so can diffuse across phospholipid bilayer 

e.g. oestrogen 

Compare the nervous and hormonal communication systems (speed, duration of effect, how message is sent)

Nervous system:

-fast communication

-short effect 

-messages are sent via nerve impulses that are carried by neurones

Hormonal system:

-slow communication 

-long duration

-messages are sent by chemical messengers (hormones) that are transported in the blood plasma