Homeostasis & Communication

Question 1

What is the definition of homeostasis?

Answer 1

The maintenance of a constant internal environment, In a normal range

Question 2

What are the three types of communication?

Answer 2

Autocrine
Paracrine
Endocrine

Question 3

Describe autocrine communication

Answer 3

Acts on the same cell

Chemical is released from cell into extracellular fluid and acts upon itself

Question 4

Describe paracrine communication

Answer 4

Chemical secreted into ECF, acts on neighboring (nearby) cells
Travel short distance, local communication
Eg. Ach at neuromuscular junction

Question 5

Describe endocrine communication

Answer 5

Secretion Into blood
Hormones act on distant cells
Can affect whole body
Eg. ADH from posterior pituitary

Question 6

What is exocrine communication

Answer 6

Secretion into ducts then into organ

Question 7

What are the key differences between Endocrine & paracrine?

Answer 7

Hormones travel in blood in endocrine, paracrine chemical messengers only travel in extracellular fluid

Endocrine affects more things and travels further than paracrine

Question 8

Describe the negative feedback loop

Answer 8

Highly regulated loop (deviation away from then return to normal)
Eg, body temp, blood sugar levels

Question 9

Describe positive feedback

Answer 9

Not a loop (Rarer)
AMPLIFICATION
Eg. Blood clotting

Question 10

What is a hormone?

Answer 10

A molecule that acts as a chemical messenger

Question 11

What are the 3 types of hormones?

Answer 11

Peptide, steroid & amino acid derivative

Question 12

Describe peptide hormones
What are they made from
How do they work
Are they fast or slow 
Premade or not?
Examples of hormones

Answer 12

Made of several AA
Large, hydrophilic, charged molecules
Water soluble; directly dissolved in blood
Bind to receptors on CSM (cannot diffuse across membrane)
Fast acting
Premade and stored in vesicles
Eg, insulin and ADH

Question 13

Describe steroid hormones
What are they made from
How do they work
Are they fast or slow 
Premade or not?
Examples of hormones

Answer 13

Made from lipid CHOLESTEROL
Lipid soluble/water insoluble (Can cross membranes require transport proteins in blood)
Transported in blood bound to a transport protein (eg, albumin)
Diffuses through CSM
Slow acting (directly affects DNA)
Eg. Oestrogen and testosterone
Not Premade

Question 14

Describe amino acid derivative hormone
What’s it made from
How does it act
Examples

Answer 14

Synthesized from tyrosine
Acts in same way to peptide
Eg. adrenaline