BIOH111 SN23 Lecture EndocrineSystem3 · edition: Chapter 18 ... o Session 23 (Lectures 45 and 46) - Pineal, ... disorders, diabetes insipidus, thyroid and parathyroid gland disorders,

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BIOH111

oCell Module

oTissue Module

oSkeletal system

oMuscle system

oNervous system

oEndocrine system

o Integumentary system


Textbook and required/recommended

readings

o Principles of anatomy and physiology. Tortora et al; 14th

edition: Chapter 18


BIOH111 – ENDOCRINE SYSTEM MODULE

o Session 21 (Lectures 41 and 42) – Hormones,

hormone receptors and molecular basis of

hormone action and regulation

o Session 22 (Lectures 43 and 44) – Hypothalamus

and pituitary, thyroid and parathyroid glands –

structure and function

o Session 23 (Lectures 45 and 46) - Pineal, thymus,

adrenal, pancreas and reproductive glands –

structure and function

BIOH111Lectures 45 and 46

Pineal, thymus, adrenal, pancreas and

reproductive glands – structure and function

Department of Bioscience

endeavour.edu.au


ObjectivesLecture 45:

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

Lecture 46:

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

Integration of hormonal actions in stress and fight-or-flight body

responses


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

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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


ObjectivesLecture 45:

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

Lecture 46:

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

Integration of hormonal actions in stress and fight-or-flight body

responses


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


Delivery of pancreas products

Hormones

from Islets

are drained

straight into

the blood

Enzymes from

acini cells are

drained into

pancreatic duct

WHY??


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


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)


STRESS RESPONSE OR GENERAL

ADAPTATION SYNDROME (GAS)

o The stimuli that produce the

stress/GAS response are

called stressors, e.g. heat or

cold, surgical operations,

poisons, infections, fever, and

strong emotional responses.

o Occurs in 3 stages:

1. Alarm (fight-or-flight) reaction

2. Resistance reaction

3. Exhaustion


1. Alarm (Fight-or-Flight) Reaction

o Nerve impulses from the

hypothalamus → sympathetic division

of the ANS → adrenal medulla

o Example: dog attack

• increases circulation

• promote catabolism for energy production

• promotes ATP synthesis

• nonessential body functions are inhibited

– digestive, urinary & reproductive


2. Resistance Reactiono Initiated by hypothalamic releasing

hormones (long-term reaction to stress)• corticotropin, growth hormone & thyrotropin

releasing hormones

o Results• increased secretion of aldosterone acts to

conserve Na+ (increases blood pressure) and eliminate H+

• increased secretion of cortisol so protein catabolism is increased & other sources of glucose are found

• increase thyroid hormone to increase metabolism

o Allow body to continue to fight a stressor

o Glucocorticoids are produced in high concentrations during stress and create many distinct physiological effects.


Exhaustion

o Exhaustion is caused mainly by loss of potassium, depletion

of adrenal glucocorticoids, and weakened organs. If stress

is too great, it may lead to death.

• Resources of the body have become depleted

• Resistance stage can not be maintained

• Prolonged exposure to resistance reaction hormones

– wasting of muscle

– suppression of immune system

– ulceration of the GI tract

– failure of the pancreatic beta cells


Stress and Disease

o Stress can lead to disease by inhibiting the immune system• gastritis, ulcerative colitis, irritable bowel syndrome, peptic

ulcers, hypertension, asthma, rheumatoid arthritis, migraine headaches, anxiety, and depression.

o people under stress are at a greater risk of developing chronic disease or of dying prematurely

o Interleukin - 1 • link between stress and immunity

• secreted by macrophages; stimulates secretion of ACTH

• stimulates production of immune substances

• feedback control since immune substance suppress the formation of interleukin-1

Clinical application:


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


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BIOH111 SN23 Lecture EndocrineSystem3 · edition: Chapter 18 ... o Session 23 (Lectures 45 and 46) - Pineal, ... disorders, diabetes insipidus, thyroid and parathyroid gland disorders,

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