Lesson 2: Hormone Function

Question 1

Hormones Function

Answer 1

Hormone function is determined by the type of hormone that is acting.

There are two main classes of hormones

Amino Acid Derived (proteins, peptides and amines)

Water soluble

Steroid

Lipid soluble

Question 2

three key events

Answer 2

Hormone signaling involves three key events:

Reception – when a hormone molecule binds to receptors on or in the target cell

Signal Transduction – the conversion of the signal to a response

Response – a change in the behaviour of the target cell

Amino Acid derived and steroid hormones each have these three steps but the mechanisms vary.

Question 3

Amino Acid Derived Hormone
Mechanism

Answer 3

The hormone binds to the receptor protein on the plasma membrane

The signal transduction pathway is activated. Relay molecules (cellular proteins) converts the extracellular chemical signal to an intercellular
response

The final relay molecule activates a protein that carries out the response.

May occur in the cytoplasm or the nucleus

Question 4

Steroid Hormone Mechanism

Answer 4

The hormone enters the cell by diffusion. Binds to a receptor protein in the cytoplasm.

The hormone-receptor complex carries out signal transduction. The complex acts as a transcription factor in the nucleus.

Bind to DNA at the enhancer region

The binding to DNA stimulates gene regulation, turning genes on or off.

Question 5

Feedback

Answer 5

Hormones work through feedback mechanisms in order to help
maintain homeostasis

There are two types of feedback;

Negative Feedback

Positive Feedback

Question 6

Negative Feedback

Answer 6

Negative feedback detects and reverses
deviations from normal body constants.

The mechanism contains three parts:

Sensor – send nerve impulses to the
brain in response to environmental
information.

Integrator – usually in the brain, sends
messages to effectors

Effector – effectors cause a change in
internal conditions.

Negative feedback loops exist throughout the body to maintain homeostasis since they reverse the effects of a stimulus.

Question 7

Positive Feedback

Answer 7

Positive feedback loops are
usually associated with disease
or change.

Positive feedback uses the same
three parts as negative feedback
but instead of reversing a
deviation, positive feedback
continues the deviation further.

An example of positive feedback
is labour.