Animal Hormones

Question 1

Why do only specific target cells respond to a hormone?

Answer 1

Because only target cells have receptors for binding with that particular hormone.

Question 2

Describe the functions of the nervous and the endocrine system:

Answer 2

-Nervous system: coordintes rapid, precise responses and mediate the body interaction with the external environment. -Endocrine system: controls processes that require duration rather than speed, especially to maintain homeostasis.

Question 3

What is a hormone?

Answer 3

A chemical mediator that is secreted by endocrine cells into the blood, where it is then transported to target cells.

Question 4

What are the four different types of extracellular communication:

Answer 4

1) Paracrines 2) Neurotransmitter 3) Hormones. 4) Neurohormones.

Question 5

Describe paracrines:

Answer 5

Local chemical messengers whose effect is exerted only on neighbouring cells in the immediate sorroundings of the receptors.

Question 6

Describe neurotransmitter

Answer 6

Released by neurons and are short distances chemical messenger.

Question 7

Describe neurohormones:

Answer 7

Hormones released into the blood by neurosecretory neurons.

Question 8

What are the 6 different functions of hormones:

Answer 8

1) Regulating metabolism, water and electrolyte balance. 2) Inducing adaptive changes to help the body cope with stressful situations. 3) Promoting smooth, sequential growth in development. 4) Controlling sexual differentiation and development.

Question 9

What are thee factors that influce the plasma concentrations of hormones:

Answer 9

1) The hormone rate of secretion into the blood. 2) The rate of metabolic activation or conversion. 3) For lipophilic hormones the extenct of binding to the plasma membrane. 4) Its rate of removal from the blod by metabolic inactivation and excretion in the urine.

Question 10

What are the 3 means of control of hormone secretion:

Answer 10

1) Negative-feedback control. 2) Neuroendocrine reflexes 3) Diurnal (circadian) Rhythms.

Question 11

Describe negative-feedback control:

Answer 11

Maintain the plasma concentration of hormone at a given level.

Question 12

Describe neuroendocrine reflexes:

Answer 12

Include neural as well as endocrine components and it produce a sudden increase in hormone secretion in resposne to specific stimulus.

Question 13

Describe diurnal (circadian) rhythms:

Answer 13

The secretion rates of many hormones fluctuate up and down as a function of time.

Question 14

What is endocrinology:

Answer 14

The study of homeostatic chemical adjustment and other activites accomplished by hormones.

Question 15

What are the two main kind of hormones based on their chemical classificatio?

Answer 15

1) Hydrophilic 2) Lipophilic

Question 16

What are Hydrophilic hormones and how are they divided?

Answer 16

Hormones that are highly soluble in water and have low lipid solubility. They are peptides or amines.

Question 17

What are amines and how are they divided?

Answer 17

Amino-acid derivates and can be either catecholamines or indoleamines.

Question 18

Describe lipophilic hormones and how are they divided:

Answer 18

High lipid solube and are poorly soluble in water. They can be either thyroid hormones or steroid hormones.

Question 19

What does the solubility of hormones determine?

Answer 19

1) How the hormones is synthesized, stored and secreted by the endocrine system. 2) How the hormone is transported by the blood. 3) How the hormone exert its effect at a target cell.

Question 20

How are hydrophilic hormones transported into the blood?

Answer 20

They simply dissolve in blood.

Question 21

How are lipophilic hormones transported into the blood?

Answer 21

They cannot dissolve in blood and are therefore bound to specific proteins.

Question 22

Where are the receptors of hydrophilic peptides hormoes located?

Answer 22

Since they canot permeate the plasma membrane the bind to specific receptors located on the plasma membrane.

Question 23

Where are the receptos for lipophilic hormones located?

Answer 23

They can pass through the plasma membrane and bind to specific receptors inside the cell.

Question 24

How do hydrophilic hormones alter cell’s proteins/function?

Answer 24

Surface-binding hydrophilic hormones function by activating a second messenger pathway. This direction directly alter the activity of pre-existing intracellular proteins to produce the desired effect.

Question 25

How do lipophilic hormones alter cell’s proteins/function?

Answer 25

They function mainly by activating specific genes in target cell to cause formation of new intracellular proteins which in turn produce the desired effect.

Question 26

What are the two hormones responsable for the correct function of molting in arthropods?

Answer 26

-PTTH -Juvenile hormone

Question 27

Describe the function of juvenile hormone:

Answer 27

Is release continously and as long as it’s present the insects molt into another juvenile individual.

Question 28

Describe the pituitary gland:

Answer 28

Is a small endocrine gland located in a bony cavity at the base of the brain just below the hypotalamus.

Question 29

Describe the function of the posterior pituitary:

Answer 29

Is an extension of the hypotalamus. It doesn’t produce any hormone, it simpy stores and releases vasopressin and oxytocin.

Question 30

Describe the anterior pituitary:

Answer 30

Consists of glandular epithelia tissue which are then released in response to hypophysiotropic hormones.

Question 31

What are the two main kinds of hypophysiotropic hormones?

Answer 31

-Stimulatory -Inhibitory.