Intro To Endocrinology

Question 1

What is the longest cell in the human body? What is it’s average length?

Answer 1

The sciatic nerve (1.2 metres)

Question 2

How do cells communicate? (IN BASIC TERMS)

Answer 2

Molecules carry messages locally or across long distances

Question 3

What types of molecules carry messages long distances?

Answer 3

Endocrine factors ( hormones & neurotransmitters)

Question 4

What are the 2 major types of cell communication?

Answer 4

Cell - cell contact & cell-cell soluble messages

Question 5

3 types of cell-cell contact communication

Answer 5

Gap junctions (small molecules between adjacent cells)
Membrane proteins (communicate between adjacent cells)
Membrane proteins (communicate with extracellular matrix)

Question 6

3 types of soluble molecules cell communication

Answer 6

Autocrine
Neural
Hormonal/endocrine

Question 7

Comparison of neural and endocrine messaging

Answer 7

Nervous system responds to stimuli through action potentials and neurotransmitters. Quick, short-lived responses.

Endocrine system responds to stimuli bu secreting hormones to travel to target tissue. Slow, long-lasting responses.

Question 8

Basic features of endocrine systems

Answer 8

1) endocrine cell
2) circulation
3) target cell

Question 9

Problems of the simplified model

Answer 9

Low concentration of hormone in circulation
Between 10^-6 and 10^-9 moll^-1
cells clump together into glands to make a larger amount; receptors are able to respond to low concentrations
Speed -> seconds to hours; long lasting effect

Question 10

What 3 things can lead to the secretion of hormones?

Answer 10

1) already soluble factors
2) another hormone
3) nervous system

Question 11

Already soluble factors- glucose example

Answer 11

Plasma glucose concentration increases
Beta cells then release the hormone insulin into the circulation
Insulin tell target cells such as skeletal muscle, liver, and fat to remove the glucose from the circulation and use it as fuel or to store it as glycogen
Plasma glucose concentration decreases

Question 12

What is meant by negative feedback loop?

Answer 12

Response causes a reduction in the original stimulus

Question 13

Insulin negative feedback loop

Answer 13

Glucose stimulates insulin, which reduces glucose levels

Question 14

3 classes of hormones

Answer 14

Peptides & proteins
Animo acid derivatives
Steroids