3.3 TheRoleOfHormoneInHuman

8/14/2019 3.3 TheRoleOfHormoneInHuman

1/35

3.3 The Role of Hormonesin Humans


2/35

What is the human

endocrine system?

System that control the secretion of

hormone in the body.

Consists of Endocrine glands

Hormones


3/35

Human Endocrine System


4/35

Are ductless (no duct or tube)

glands.

Release hormones directly into

the interstitial fluid and

subsequently into the bloodstream

a) Endocrine glands


5/35

a) Endocrine glands


6/35

Chemical messengers produced by

endocrine glands

Travel in the blood,

Affect and influence only specific target

cells

Bind to specific receptor molecules on thesurface of the plasma membrane of the

target cells

b) Hormones


7/35

How endocrine system

work


8/35

The endocrine system and the nervous

system play important roles in

maintaining homeostasis.

A correction mechanism in the body

which reacts through hormones or

nerves to correct the values of physical

or chemical factors that are distortedfrom the normal value

The Need for The

Endocrine System


9/35

The endocrine system usually

complements the nervous system.

When we dehydrated, our blood osmotic

pressure increase. This stimulates

neurones in the hypothalamus which in

turn active cells in the pituitary gland to

release the antidiuretic hormone (ADH).ADH causes the kidney to retain more

water. Thus, the osmotic pressure

decreases and returns to normal again

The Need for The

Endocrine System


10/35

1. Involve in Physiological processes (e.g.

menstrual cycle, the development of

secondary sexual characteristics and

growth)

The hormones released by the

endocrine system regulate a wide

range of activities (e.g. rate ofheartbeat, metabolism, sugar level and

salt concentration.

The Need for The

Endocrine System


11/35

ifferences between the nervous and the endocrine system

Types of message

Characteristics

Transport

Speed of

transmission

Area of response

Body processes

involved

Nature of theresponse

Duration of effect

Endocrine SystemNervous SystemNervous System

Electrical signals(nerve impulses)

Via neurones

Rapid

Specific locations

Causes muscles to contract

Temporary

Controls both voluntary and

involuntary actions

Chemical signals(hormones)

Via the bloodstream

Slow

Various destinations(to the target cells)

Causes changes in themetabolic activity

Long-lasting

Growth, reproduction,development

Control involuntary action


12/35

Test Yourself

hypothalamus

thyroid gland

thymus gland

adrenal gland

pancreas

ovary testis

pituitary gland


13/35

Function of hormones

Reproduction Growth Homeostasis

Follicle stimulatinghormone, Luteinisinghormone, Oestrogens,Progesterone andAndrogens

Insulin, glucagon,antidiuretic hormonand adrenaline

Growth hormone,Thyroid-stimulatingHormone andthyroxine


14/35

Endocrine Gland, Function &

Hormones Secreted


15/35


Hormones Secreted


16/35


Hormones Secreted


17/35

Test yourselfTest yourself

1. What is the human endocrine system?

2. What is hormone?

3. How many glands do a person have

and what are they?

4. Give an example of hormone release

by each gland.


18/35

1. An endocrine gland releases its hormone

when stimulated.

2. Hormone secretion is regulated toprevent over production or under

production.

Regulation of Hormone

Secretion


19/35

Regulation of Hormone

Secretion

Hormone secretion is regulated by

Signals from thenervous system

Other hormonesThe level of

specific substances

in the body


20/35

The regulation of hormone

secretion by signals from the

nervous system

1. Hypothalamus

Has specialised cells called neurosecretory

cells which produce hypothalamic releasingand inhibiting hormones

Link the nervous and endocrine system

Controlling the secretion of hormones from

the pituitary gland to maintain homeostasis


21/35



nervous system


22/35

The pituitary gland is the master endocrine

gland

Secretes several hormones that controlother endocrine glands

Controlled by the hypothalamus

Consists of two parts: the anterior and the

posterior pituitary



nervous system


23/35

Others endocrine glands that secretionsare regulated by nervous system are:

The adrenal medulla receives impulses

from the efferent nerves of the nervoussystem and secretes adrenaline inresponse

The pancreas after meal, the pancreas

receives efferent impulses from the CNSto secrete insulin to reduce the bloodglucose level



nervous system


24/35

The regul ati on of hormonesecretion by other hormones The secretion of thyroxine is regulated

by the thyroid-stimulating hormone

b) The pituitary gland secretes the thyroid-

stimulating hormone (TSH) to stimulatethe thyroid gland to produce thyroxine

c) The more TSH the thyroid glandreceives, the more thyroxine it secretes

d) In turn, less TSH reduces the activity ofthe thyroid gland, causing a drop in thelevel of thyroxine


25/35


26/35

Hormones luteinising hormone (LH)

stimulates secretion of oestrogen,

progesterone and testosterone. Hormone adrenocorticotrophic

hormone (ACTH) stimulates adrenal

cortex to release adrenalin andnoradrenaline hormones from adrenal

gland

The regul ati on of hormonesecretion by other hormones


27/35

The regulation of hormone secretion

by the level of specific substances in

the blood

E.g. blood glucose level increase the

pancreas produces insulin causes an

increase in the glucose uptake by cells

the cells either metabolise the glucose orconvert it to glycogen

What happen if blood glucose level

decrease?

Pancreas will secrete more glucagon which

converts glycogen to glucose


28/35

Test yourselfTest yourself

1. What regulates the secretion of

hormone?

2. Explain in brief how each factorregulates the secretion of hormone.


29/35

The involvement of both the nervous

system and the endocrine system in a

'fight or flight" situation

During a threatening situation, for example,

when a dog suddenly barks and chases you,

our heart will beats faster.

During these moments of 'fight or flight', the

hypothalamus sends nerve impulses directly

to the adrenal medulla to secrete adrenaline

and noradrenaline.


30/35

The adrenal medulla, which is the innermostregion of the adrenal gland, has neuronesfrom the sympathetic division of the

autonomic nervous system. In this situation a heartbeat, breathing

rates, blood pressure, blood glucose leveland metabolic activity will increases.

The skeletal muscles become moreenergised and enable a person to fight offan attacker or flee immediately from danger.

The involvement of both the nervous

system and the endocrine system in a

'fight or flight" situation


31/35

The Sequence of Events


32/35

Hormonal Imbalances & Related DiseasesHormonal Imbalances & Related Diseases

Hormonal Imbalances & RelatedHormonal Imbalances & Related


33/35


DiseasesDiseases



34/35


DiseasesDiseases


35/35

ExerciseExercise

Do Checkpoint 3.3 on page 97 in your

textbook.

Change question No. 3 to this question:3. How do excess hormone removed from

the blood?

Documents

3.3 TheRoleOfHormoneInHuman