BIOH111 SN23 Lecture EndocrineSystem3 · ... Chapter 18; sections 18.1, 18.9, ... (Lectures 45 and 46) ... disorders, diabetes insipidus, thyroid and parathyroid gland disorders,

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BIOH111

oCell Module

oTissue Module

o Integumentary system

oSkeletal system

oMuscle system

oNervous system

oEndocrine system


Textbook and required readings

o Glands: Principles of anatomy and physiology. Tortora et

al; 14th edition: Chapter 18; sections 18.1, 18.9, 18.10,

18.11, and 18.12

o Hormonal axes: Hiller-Sturmhofel & Bartke, 1998


BIOH111 – ENDOCRINE SYSTEM MODULE

o Session 23 (Lectures 43 and 44) – Hormones,

hormone receptors and molecular basis of hormone

action and regulation

o Session 24 (Lectures 45 and 46) – Hypothalamus and

pituitary, thyroid and parathyroid glands – structure and

function

o Session 25 (Lectures 47 and 48) - Pineal, thymus,

adrenal, pancreas and reproductive glands – structure

and function and hormonal axes

o Session 26 – Integration of nervous and endocrine

systems

BIOH111Lectures 47 and 48

Pineal, thymus, adrenal, pancreas and

reproductive glands (structure and function)

and hormonal axes

Department of Bioscience

endeavour.edu.au


ObjectivesLecture 47:

Pineal, thymus and adrenal glands

• Define the structure of pineal and thymus gland and relate it to the secretion of their

hormones

• Define the structure of adrenal gland and relate each structural component to the

secretion of respective hormones

• Define regulation of adrenal gland hormones secretion

Pancreas and reproductive glands (ovaries and gonads)

• Define the structure of pancreas and relate it to its function in secretion of hormones and

enzymes

• Describe regulation of blood glucose levels

• Describe functions of reproductive glands

• Define and describe actions of other endocrine glands and factors

Lecture 48:

Hormonal axes

• Define and describe the structure and function of the 4 major hormonal axes: HPA, HPT,

Female HPG and Male HPG


ENDOCRINE GLANDS


PINEAL GLAND

o Structure: small gland attached to

3rd ventricle of the brain; part of

epithalamus; cells - pinealocytes &

neuroglia

o Function: production of melatonin:

• responsible for setting of biological

clock

• secretion produces sleepiness occurs

during darkness due to lack of

stimulation from sympathetic ganglion

• Jet lag and seasonal effective disorder

treatment is bright light


THYMUS GLAND

o Hormones promote the

proliferation and maturation of

T cells: some examples

include:

• thymosin

• thymic humoral factor

• thymic factor

• thymopoietin


ENDOCRINE GLANDS


ADRENAL GLAND

o Location: superior to the kidneys

o Structure: 3x3x1cm in size and weighs 5 grams; consists of

an outer cortex and an inner medulla


1. Adrenal cortex

o Structure and function: regulated by hormonal actions; divided into three zones, each secretes different hormones:

1. Zona Glomerulosa (outer zone) - secretes Mineralocorticoids

2. Zona Fasciculata (middle zone) – secretes glucocorticoids

3. Zona Reticularis (inner zone) – secretes androgens

his

tolo

gy o

f adre

nal c

orte

x


Blood flow through the adrenal gland

pt-br.infomedica.wikia.com

http://pt-br.infomedica.wikia.com/wiki/Conhecendo_as_supra-renais


Hormones of adrenal cortex1. Mineralocorticoids:

• 95% of hormonal activity due to aldosterone

• Functions: regulate mineral balance

increase reabsorption of Na+ with Cl- , bicarbonate and water

promotes excretion of K+ and H+

2. Glucocorticoids

• 95% of hormonal activity is due to cortisol

• Functions: regulate glucose metabolism and resistance to stress:

increase rate of protein catabolism & lipolysis

provide resistance to stress by increasing ATP production

reduce immune responses and anti-inflammatory effects

3. Androgens

• Functions: regulate masculinization

• Small amount of male hormone produced

insignificant in males; may contribute to sex drive in females; converted to

oestrogen in postmenopausal females


Regulation and action of aldosteroneKidneys

(juxtaglomerular cells)Adrenal cortex Kidneys

(glomerulae)

Liver Lungs

aldosteronerenin/angiotensin


Regulation of

glucocorticoids

o Negative feedback


o Structure: chromaffin cells

receive direct innervation

from sympathetic nervous

system

o Function: production of

epinephrine &

norepinephrine hormones

that cause fight-flight

behavior (these hormones

are sympathomimetic -

effects mimic those of

sympathetic NS)

2. Adrenal medulla

homepage.smc.edu

http://homepage.smc.edu/wissmann_paul/intranetstuff/dept/scienceLRC/wissmann_site/adrenal.htm


PANCREAS

o Structure: flattened organ located posterior and slightly inferior

to the stomach; consists of head, body and tail, 12 cm in length

o Function: classified as both an endocrine (Islets of

Langerhans) and an exocrine (acini) gland


Islets of Langerhans

o 1 to 2 million pancreatic islets;

each contains 4 types of

endocrine cells:

1. Alpha cells (20%)

• produce glucagon

2. Beta cells (70%)

• produce insulin

3. Delta cells (5%)

• produce somatostatin

4. F cells (5%)

• produce pancreatic

polypeptide


Acini cells

o Contain zymogen

granules that contain

digestive enzymes and

are released by secretion

This aspect will be covered in more detail in BIOH111


Delivery of pancreas products

Hormones

from Islets

are drained

straight into

the blood

Enzymes from

acini cells are

drained into

pancreatic duct

WHY??

This

aspect w

ill be c

overe

d

in m

ore

deta

il in B

IOH

111


REGULATION OF BLOOD GLUCOSE

LEVELS

o Negative feedback

mechanisms regulate

secretion of glucagon and

insulin:

o Low blood glucose stimulates

release of glucagon

o High blood glucose stimulates

secretion of insulin

Why do we need insulin secreted in response to

increase in blood glucose levels? So cells can

bring glucose transporter to the plasma

membrane by regulated secretion.. - revision

STIMULUS

(insulin interacting

with its receptor)

Which cells do you think

this process happens in

and why?


ENDOCRINE GLANDS


OVARIES AND TESTES

o Ovaries

• Hormones produced: oestrogen,

progesterone, relaxin & inhibin

• Function: regulate reproductive

cycle, maintain pregnancy &

prepare mammary glands for

lactation

o Testes

• Hormone produced: testosterone

• Function: regulate sperm production

& secondary sexual characteristics

Ovary

Testis


OTHER HORMONES AND

GROWTH FACTORSo Several body tissues also contain endocrine tissue and

produce and secrete hormones:

1. Eicosanoids – family of local hormones produced by all cells in the

body from omega-3 and omega-6 fats; function: smooth muscle

contraction, glandular secretion, blood flow, platelet function, nerve

transmission, metabolism (e.g. prostaglandin) and influences on

WBCs and inflammation (e.g. leukotrienes)

2. Growth factors – family of proteins secreted by most cells in the

body; act in autocrine or paracrine manner through cell membrane

receptors; function in differentiation and/or proliferation; e.g.

epidermal growth factor (EGF), fibroblast growth factor (FGF),

insulin-like growth factor (IGF)


Revision

Read one of the following: section 18.16 or Homeostatic Imbalances

(Tortora, p 652) and define following terms: aging, pituitary gland

disorders, diabetes insipidus, thyroid and parathyroid gland disorders,

Cushing’s syndrome, Addison’s disease and pancreatic islet

disorders. Then in groups of 2-3 think about:

- What are the risk factors for these processes, conditions and

disorders?

- Describe structural and comment on molecular level changes that

occur in these muscle disorders and conditions.

- Link the described causes and affected muscle physiology to

comment on possible treatments of these disorders within your

particular interest.

Non assessable


ObjectivesLecture 47:

Pineal, thymus and adrenal glands

• Define the structure of pineal and thymus gland and relate it to the secretion of their

hormones

• Define the structure of adrenal gland and relate each structural component to the

secretion of respective hormones

• Define regulation of adrenal gland hormones secretion

Pancreas and reproductive glands (ovaries and gonads)

• Define the structure of pancreas and relate it to its function in secretion of hormones and

enzymes

• Describe regulation of blood glucose levels

• Describe functions of reproductive glands

• Define and describe actions of other endocrine glands and factors

Lecture 48:

Hormonal axes

• Define and describe the structure and function of the 4 major hormonal axes: HPA, HPT,

Female HPG and Male HPG


Tropic hormone

Endocrine gland

+

Target organ

Y Receptor

Hormone

Action

Hypothalamus

Pituitary gland

CONTROL OF HORMONE SECRETION

Horm

onal axis

+/-

+/-

Positiv

e a

nd n

egativ

e lo

ops

Direct regulation

+/-


DIRECT REGULATION OF BLOOD

GLUCOSE LEVELS - revision

o Negative feedback

mechanisms regulate

secretion of glucagon and

insulin:

o Low blood glucose stimulates

release of glucagon

o High blood glucose stimulates

secretion of insulin


DIRECT REGULATION OF CALCIUM

BLOOD LEVELS - revisionBlood calcium level directly controls the secretion of calcitonin and

parathyroid hormone via negative feedback loops that do not involve

the pituitary gland:


Tropic hormone

Endocrine gland

+

Target organ

Y Receptor

Hormone

Action

Hypothalamus

Pituitary gland

HORMONAL AXES – general overview

Horm

onal axis

+/-

+/-

Positiv

e a

nd n

egativ

e lo

ops


METABOLIC AXIS - HPA

Hiller-Sturmhofel & Bartke, 1998

Regulation:Circadian rhythm

StressBlood volume

Hypothalamus: CRH ADH

Pituitary gland: ACTH

Gland/target:Adrenal

cortexKidney

Target hormones:Cortisol

Androgen

Function: Stress Water balance


METABOLIC AXIS - HPT


Regulation:Thyroid hormone

levels

Hypothalamus: TRH

Pituitary gland: TSH

Gland/target:

Target hormones: T4/T3

Function: Metabolism

Thyroid


METABOLIC AXIS - FEMALE HPG


Regulation/

Hormone :

Estrogen, Progesterone,

Androgen, Prolactin,

Inhibin

Hypothalamus: GnRH

Pituitary gland:LH

FSH

Gland/target:

Function: Reproduction

Gonads

(ovaries)

Estrogen

Stress

Dopamine

Prolactin

Lactation

Breast


METABOLIC AXIS - MALE HPG


Hypothalamus: GnRH

Pituitary gland:LH

FSH

Gland/target:

Target hormones: Testosterone

Function: Reproduction

Gonads

(testes)


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BIOH111 SN23 Lecture EndocrineSystem3 · ... Chapter 18; sections 18.1, 18.9, ... (Lectures 45 and 46) ... disorders, diabetes insipidus, thyroid and parathyroid gland disorders,

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