Control systems of the body The nervous system working through nerve impulses so it is a rapid control system 2 The hormonal or endocrine system working through hormones in blood so it is a slow control system ID: 681130
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Slide1
Pathophysiology
of
Endocrine glandsSlide2
Control systems of the body
The
nervous system : working through nerve impulses, so it is a rapid control system.2) The hormonal, or endocrine system: working through hormones in blood, so it is a slow control system.
The functions of the body are regulated by two control systems:Slide3
Definitions
Hormone:
are special chemical messengers in the body that are secreted directly into the blood . These messengers control most major bodily functions.Hormones are secreted from the endocrine glands in the bodyEndocrine glands:
are ductless glands which secrete hormones directly to the blood.
They are:
1- Pituitary gland
2- Thyroid gland
3- Parathyroid gland
4- Supra renal gland
5- Pancreas
6- GonadsSlide4
Endocrine glands:
These organs secrete hormone in microscopic
amounts. Even a very slight excess of hormone secretion can lead to disease states, as can the slightest deficiency in a hormone.Slide5
The pituitary is an important gland in the body and it is often referred to as the 'master gland', because it controls several of the other hormone glands
Pituitary gland
(Hypophysis Cerebri)It is
found at the base of the brain, behind the bridge of
the nose
.
It is
very close to
hypothalamusSlide6
Pituitary gland
(
Hypophysis Cerebri)It is divided into 2 parts:Anterior pituitary: that secretes:1- Growth hormone
2- Prolactin
hormone
3-Trophic
Hormones
a-TSH
thyrotropin
that act on
Thyroid gland.
b- ACTH Adrenocorticotrophic hormone
that act on
Adrenal cortex.
c- GTH
Gonadotropin
hormone
(LH & FSH
) that act on
Gonads.
Posterior pituitary: that secretes:
1-Antidiuretic hormone (ADH).
2-Oxytocin hormone.Slide7
Pituitary glandSlide8
Growth hormone
Growth hormone is a protein hormone secreted by the anterior
pituitary into the bloodstream.Anterior pituitary
Growth hormone acts on many parts of the body to
promote growth in children
.
In
adults, it does not cause growth but it helps to maintain normal body structure and metabolism, including helping to keep blood glucose levels within set levels.Slide9
Functions
:
I) Growth effects:
1-Stimulation of growth of bones in length
2-Stimulation of growth of soft tissues
e.g
, muscles and organs (liver, heart, kidney,….
etc
).
3-Formation of various body fluids,
e.g
, plasma and interstitial fluid.
4-Stimulation of erythropoiesis→ increased RBCs count.
5-Stimulation of protein synthesis (protein anabolic hormone)Slide10
Clinical Abnormalities in growth hormone Secretion:
Decreased GH secretion before puberty --->
Pituitary dwarfismIncreased GH secretion before union of epiphysis ---> GigantismIncreased growth hormone secretion, after union of epiphysis --->
acromegalySlide11Slide12
Pituitary dwarfism
Occurs as a result of
decreased secretion of growth hormone before union of epiphyses.Causes: Genetic disorders but the causes of some disorders are unknown.Manifestations:
1) Symmetrical retardation of the growth of long
bones; the
pituitary dwarf is not more than 100-120 cm in height in adult age-
2) Symmetrical retardation of the growth of soft tissues.
3
)
Fascial
features are crowded in the middle of the face giving the characteristic doll face.
4) Mentality of the pituitary dwarf is
normal, but
emotionally unstable.Slide13
Pituitary dwarfismSlide14
Gigantism
*Results
from overproduction of growth hormone by the pituitary gland in the pre-adult life, i.e. before union of epiphyses.A pituitary gland tumor is almost always the cause of gigantism
*
Characteristic Features:
1) Delayed union of the epiphyses ---> over-growth of the skeleton and the giant height may reach 2
meters
.
2) Symmetrical over-growth of soft tissues:
3
)
HypogonadismSlide15
Acromegaly
*
Results, from over-production of GH during adult life, i.e. after union of epiphyses, usually caused by a benign tumour of the pituitary gland.
*Characteristic
Features
(1)It can
not
causes
further increase in height of the person, but it causes
disproportionate growth of thickness of long bones
as well as
continued growth of membranous bones
that have no epiphyses to unite
e,g
. jaws and
skull
.
a
)
Skull
:
Is
characterized
by:
Enlarged
nose which may be double the normal size.
Mandible: becomes broad ---> Teeth separation and
prognathism
.
b
) Hands and Feet
:
are thick and broad. (2) Hypogonadism.Slide16
Giantism
acromegalySlide17
Posterior pituitary: that secretes:
1-Antidiuretic hormone (ADH).
2-Oxytocin hormone.Slide18
Antidiuretic hormone(ADH)
or
vasopressinActions:Increases water
reabsorption
from the distal tubules and collecting ducts of the kidney→ increases the volume of body fluids and decreases the urine volume.Slide19
Diabetes
Insipidus
* Causes:1 Decreased ADH secretion .2 Failure of the kidney to respond to ADH .
*
Characters:
1-
Polyuria
: due to failure of H
2
O
reabsorption
. Urine volume increases up to 20 liters/day with low specific
gravity.
2- Loss of H
2
O soluble vitamins --->
hypovitaminosis
.
3-
Polydepsia
: means increased fluid intake caused by thirst sensation which is secondary to
polyuria
.Slide20
Thyroid Gland
Structure
:An endocrine gland present in front of the lower part of the neck just below the larynx.Thyroid gland contains:1) Follicular A cells: secretes thyroxin (T4) and tri-
iodothyronine
(T3).
2)
Parafollicular
C cells :
secretes calcitonin (calcium lowering hormone).Slide21
Parafollicular
C cells
1)Follicular A cells
Thyroid GlandSlide22
Thyroid hormone (T3&T4)
Functions:
1-Physiological doses of thyroid hormones stimulate protein synthesis (protein anabolic).2-Stimulation of all aspects of glucose metabolism: absorption from GIT, uptake by the tissues and production by the liver.
3-Thyroid
hormones are essential for mental and skeletal growth in infants and growing
childrenSlide23
Clinical Abnormalities in thyroid hormone Secretion
Hypothyroidism:
- In infants and young children ---> Cretinism - In older children and adults ---> Myxedema
Hyperthyroidism
at any age
--->
thyrotoxicosis or toxic goiterSlide24
Cretinism
*
Causes:1- Congenital absence of thyroid gland. 2- Failure of thyroid gland to produce active thyroid hormones.3- Iodine lack in the diet (endemic cretinism
).
*
Manifestations
:
-
Start to appear few months after birth .
Delayed
physical
growth:
a-
Delayed eruption of teeth.
c-
Delayed sitting and
walking
2) Failure of mental development:
So the cretin:
-Is idiot,- Is incontinent to urine and stools
, and has
defective speech.
Treatment:
With thyroid hormone returns of physical growth. But unless the cretin is treated in the first few months after birth, permanent retardation of mental growth will take place.
Slide25Slide26
MYXEDEMA
Caused by
decreased secretion of thyroid hormones in older children and adults.
Hypothyroidism may be due to a number of factors,
including:
Autoimmune
disease
Treatment for hyperthyroidism.
Thyroid
surgery.
Radiation
therapy.
Medications
.
Pituitary disorder. A relatively rare cause of hypothyroidism
Iodine deficiencySlide27
MYXEDEMA
Manifestations:
Metabolic:Decreased BMR; patient cannot tolerate cold weather Dry and yellow skinIncreased body
weight
Increased blood cholesterol
Basal metabolic rate (BMR) refers to the minimum amount of energy -- in the form of calories -- that your body requires to complete its normal functions
II) Systemic:
1-CNS:
-
Poor
memory ,Slow thinking and speech., Hypersomnia .
Eyes
are
swollen eye lid
, night
blindness ,loss of outer third of eye browSlide28
THYROTOXICOSIS
Caused by
increased secretion of thyroid hormones at any ageManifestations:Metabolic:Increased BMR; patient cannot tolerate hot weather Moist and
flushy
skin
Decreased
body
weight
Decreased blood cholesterol
II) Systemic:
Increased excitability and irritability
,
Fine tremors, Insomnia. Increased appetite,
Exophthalmos in 30% of
patients,
Increased heart rate and cardiac output
Slide29
Toxic
goitre
MyxedemaSlide30
Thyroid Function Tests
I.
Nonspecific testsl. BMR 2. Serum cholesterol
II. Specific tests
Protein
bound iodine (PBI)
Radioactive iodine uptake by thyroid gland
Radioimmunoassay of plasma T4 , T3 (free and total) and TSH
Slide31
Thyroid Gland
Thyroid gland contains:
1) Follicular A cells: secretes thyroxin (T4) and tri-iodothyronine (T3).
2)
Parafollicular
C cells :
Secretes calcitonin (calcium lowering hormone).Slide32
Hormones of calcium homeostasis
Functions of calcium:
1) Bone and teeth mineralization.2) Blood coagulation .3) In neuromuscular system : calcium is important for : * Normal excitability of nerves * Neuromuscular transmission.
* Muscle contraction.
4) In endocrine glands, calcium mediates the secretion and action of hormones.
5) Calcium is important for ATP formation in the mitochondria and ATP utilization in the cell.
6) Calcium is essential for normal cell membrane permeability and cell proliferation.Slide33
Hormones of calcium homeostasis
Hormonal Control of Calcium Homeostasis:
The blood level of ionisable calcium is kept constant mainly by 3 hormones:I. Parathormone
:
Ca
++
raising hormone
II.
Calcitonin
:
Ca
++ lowering hormone
Ill.
1, 25
dihydroxy
cholecalciferol
which is vitamin D3 metabolite : Ca
++
raising hormoneSlide34
Tetany
Definition:
a state of increased neuromuscular excitability resulting from decreased blood level of ionized calcium.Causes of decreased Ca++ concentration in blood:
1-
Hypoparathyroidism
.
2-
Vitamin D deficiency → decreased Ca
++
absorption from the intestine e.g. rickets and
osteomalacia
.
3- Excessive administration of oxalates or citrates.
4- Renal failure .
Types: Two types:
I. Manifest
tetany
.
II. Latent
tetany
.Slide35
Carpopedal
spasmSlide36
The adrenal
glands =Suprarenal gland
In the body, there are two suprarenal glands, each lies at the superior pole of the corresponding kidney.Each gland consists of 2 distinctive parts: *Suprarenal medulla (central):
secretes
catecholamines
(epinephrine and
norepinephrine
) and
*
Suprarenal cortex(peripheral):
secretes corticosteroids.Slide37
Suprarenal glandSlide38
SUPRARENAL CORTEX
Consists of 3 zones which secrete 3 groups of hormones. All are steroid in nature:
1) Zona
Glomerulosa
Secretes
mineralocorticoids
. mainly
aldosterone
which:
a- Regulate Na
+
, K
+
and H2O metabolism.
b- Have weak glucocorticoid-like activity
2)
Zona
Fasciculata
:
Secretes glucocorticoids, mainly
cortisol
which:
a- Regulate CHO, protein and fat metabolism
b- Have weak mineralocorticoid-like activity.
3) Zona
Reticularis
Secretes sex hormones mainly
androgen (
dehydroepiandrosterone
DHEA) and little estrogen
N.B,:
Cortisol
and
aldosterone
are essential to life.Slide39
SUPRARENAL CORTEXSlide40
Cortisol
hormone (
contin)II. Cortisol has the following actions (pharmacological actions):Antistress effect of
cortisol
:
2) Anti-inflammatory effect of
cortisol
:
3)
Antiallergic
effect of
cortisol
:
4) Effect on blood cells and immunity:
Cortisol
increases the number of RBCs →
polycythemia
Cortisol
decreases the number of
esinophils
and lymphocytes → decreased level of immunity for all foreign invaders. Slide41
Cushing's Syndrome
•
Cause: Increased cortisol secretion from the suprarenal cortex .• Characteristics:1) Metabolic Effects:A-Fat Metabolism: mobilization of fats from the lower part of the body with its deposition in the: head region →moon face and thorax & upper abdomen →buffalo torso.
b
) CHO
Metabolism:
hyperglycemia
c) Protein
Metabolism:
1- Decreased protein content of skin
→ damages and delayed wound healing
2- muscle weakness.
3-Decreased
protein content of
bones (Osteoporosis)
2) Excess androgenic activity
→ acne and hirsutismSlide42
Cushing syndrome Slide43
adrenal cortex Secretion
Increased secretion of :
Aldosterone hormone → Conn’s syndrome Cortisol
hormone → Cushing syndrome
Decreased secretion of adrenal cortex
→
Addison’s diseaseSlide44
Addison's Disease
Cause:
Decreased secretion of adrenal cortex1) Atrophy of adrenal cortex by autoimmune disease.2) Destruction of adrenal cortex by tuberculosis or cancer.
Characteristics:
1
)
Decreased mineralocorticoids
→
•
hypotension
and
shock.
• Hyperkalemia and acidosis
.
2
) Decreased glucocorticoids
→
hypoglycemia.
Treatment
:
Small quantities of mineralocorticoids and glucocorticoids are administered
dailySlide45
Pancreatic hormones
- Pancreas consists of 2 types of tissues:
Acini (exocrine part): which secrete digestive juices into the duodenum.2) Islets of Langerhans
(endocrine Part): which secrete hormones directly into the blood. These islets contain 4 types of cells (Fig.):
1- B or beta cells (60%)→secrete insulin hormone
2- A or alpha cells (25%) → secrete glucagon hormone
3- D or delta cells (10%) → secrete somatostatin hormone
4- PP cells (5%) →pancreatic polypeptide.Slide46
Endocrine and exocrine pancreasSlide47
Insulin hormone
Is a protein hormone secreted by the beta cells of islets of
Langerhans.Functions:- On CHO Metabolism: insulin is a hypoglycemic Hormone
- On Protein Metabolism:
insulin is a protein anabolic hormone
- On Fat Metabolism:
insulin is a
lipogenic
hormone
- On K
+
Metabolism:
insulin causes K
+
to enter the cellsSlide48
Diabetes Mellitus
It is due to
decreased secretion of insulin by B cells of islets of Langerhans.If it begins in early life juvenile diabetes mellitus If it begins in later life
maturity onset diabetes mellitus
.
Pathophysiology Of Diabetes Mellitus
A) Decreased glucose uptake and utilization
by body cells leading to hyperglycemia .
1 Dehydration of the cells.
2-
Glucosuria
osmotic diuresis, polyuria, and polydipsia
B) Increased protein catabolism
→ muscle weakening
C) Increased
lipolysis
increased free fatty acids in the blood that pass to the liver
fatty liver
D) Metabolic Acidosis :
caused by: aminoacidemia and
lactiacidosis
Slide49
Glucose tolerance testSlide50
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