Functional_anatomy_and_physiopathology_of_hypothalamus_and_adenohypophisis.ppt

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1. FUNCTIONAL ANATOMY
AND PHYSIOPATHOLOGY OF
HYPOTHALAMUS AND
ADENOHYPOPHISIS
PHYSIOTHERAPY IN
ENDOCRINE PATHOLOGY

2. Outline and objectives of the
course
Outline Objectives
HYPOTHALAMUS -Describe the location, structure and function of
the hypothalamus
-Describe the hormons of the hypothalamus
HYPOPHISIS
Hormones of the
adenohypophisis
Regualation of the
AdenoHy hormones
Hormones of the
neuroHy
Pituitary disorders
-Explain the functions of anterior pituitary
hormones and how they are regulated
-Explain the functions of posterior pituitary
hormones and how they are regulated
- Summarise the characteristics of pituitary
disorders

3. HYPOTHALAMUS -
STRUCTURE

4. OVERVIEW

Located inferior to the talamus

Represents the ventral region of the
midbrain

Center of homeostasis

5. GENERAL PRESENTATION

The hypothalamus (from Greek ὑποθαλαμος = under the
thalamus) is a region of the mammalian brain located below
the thalamus, forming the major portion of the ventral region
of the diencephalon and functioning to regulate certain
metabolic processes and other autonomic activities.

The hypothalamus links the nervous system to the
endocrine system via the pituitary gland, also known as the
"master gland," by synthesizing and secreting neurohormones,
often called releasing hormones, as needed that control the
secretion of hormones from the anterior pituitary gland —
among them, gonadotropin-releasing hormone (GnRH). The
neurons that secrete GnRH are linked to the limbic system,
which is primarily involved in the control of emotions and
sexual activity. The hypothalamus also controls
body temperature, hunger, thirst, and circadian cycles.

6. GENERAL PRESENTATION

The hypothalamus co-ordinates many seasonal
and circadian rhythms, complex patterns of
neuroendocrine outputs, complex homeostatic
mechanisms, and many important stereotyped
behaviours. The hypothalamus must therefore
respond to many different signals, some of which
are generated externally and some internally. The
hypothalamus is thus richly connected with many
parts of the CNS, including the brainstem
reticular formation and autonomic zones, the
limbic forebrain (particularly the amygdala,
septum, diagonal band of Broca, and the
olfactory bulbs, and the cerebral cortex).

7. FUNCTION

The hypothalamus is responsive to:

Light: daylength and photoperiod for generating circadian
and seasonal rhythms

Olfactory stimuli, including pheromones

Steroids, including gonadal steroids and corticosteroids

Neurally transmitted information arising in particular from
the heart, the stomach, and the reproductive tract

Autonomic inputs

Blood-borne stimuli, including leptin, ghrelin, angiotensin,
insulin, pituitary hormones, cytokines, plasma
concentrations of glucose and osmolarity etc

Stress

Invading microorganisms by increasing body temperature,
resetting the bodys thermostat upward.

8. The hypothalamus is a very
complex region, and even small
nuclei within the hypothalamus
are involved in many different
functions. The
paraventricular nucleus
contains oxytocin and
vasopressin neurons which
project to the posterior pituitary
, but also contains neurons that
regulate ACTH and TSH
secretion (which project to the
anterior pituitary),
gastric reflexes,
maternal behavior,
blood pressure, feeding,
immune responses, and
temperature.

9. Hypothalamic nuclei

Medial Area

Anterior

Medial preoptic nucleus
Supraoptic nucleus
Paraventricular nucleus
Anterior nucleus
Suprachiasmatic nucleu
s

Tuberal

Dorsomedial nucleus
Ventromedial nucleus
Arcuate nucleus

Posterior

Mammillary nuclei (part
of mammillary bodies)
Posterior nucleus
-
Lateral Area
Anterior
Lateral preoptic
nucleus
Lateral nucleus
Part of supraoptic
nucleus
Tuberal
Lateral nucleus
Lateral tuberal nuclei
Posterior
Lateral nucleus

10. Hormones of the
hypothalamus

Corticotropin-releasing hormone (CRH)

Dopamine

Gonadotropin-releasing hormone (GnRH)

Growth hormone releasing hormone (GHRH)

Somatostatin

Thyrotropin-releasing hormone (TRH)

Hypocreatin

Antidiuretic Hormone (ADH)

11. HT role in obesity
An important aspect of hypothalamic
autonomic control with regard to the
endocrine system is the control of
food intake. The effects of obesity on
endocrine function can be
widespread and endocrine
abnormalities can cause obesity. A
number of hormones play central
roles in the control of food intake

12. Measures of obesity

Three main experimental measures of fat mass in man have been used
for many years. They require the determination of body density, water
or potassium content and the assumption that the body composition
can be divided into fat and fat-free or lean body mass with certain
characteristics. These techniques are relatively costly, time-consuming
and do not give information on the distribution of the fat.

Techniques such as bioelectrical impedance rely on the fact that fat is
not as good an electrical conductor as lean body mass. It is cheap but
also does not allow an assessment of the distribution of the fat mass.

Imaging techniques such as CT or MR allow the determination of fat
from a number of tomographic 'slices' of the body. The distribution of
the fat mass can be calculated.

Simple anthropomorphic measurements such as height and weight
allow the calculation of body mass index (BMI), whilst calipers can be
used to measure subcutaneous fat.

BMI = body weight (in kg)/height2 (in m)

Waist/hip circumference = ratio of waist circumference to that of the
hips

13. HIPOPHYSIS (pituitary gland)

O,5-0,8 G

anterior pituitary (adenohypophysis)

posterior pituitary (neurohypophysis)

Regulated by hypothalamus –
providing anatomical and
physiological connections between
nervous and endocrine system

14. ADENOHYPOPHYSIS
Connected with the hypothalamus via
the hypophyseal portal system
NEUROHYPOPHYSIS
Connected with the hypothalamus via
the hypophyseal tract

15. HORMONES OF THE
ADENOHYPOPHISIS

Somatotropin (growth hormone)

Prolactin

Gonadotropines: follicle-stimulating
hormone (FSH); luteinizing hormone
(LH)

Thyroid stimulating hormone (TSH)

Adrenocorticotropic hormone (ACTH)

16. Thyrotropin

Stimulates the thyroid gland to
synthetize and secrete its hormones
(triiodothyronine – T3; thyroxine – T4)
Regulation by negative feedback ( high
concentration of T3 and T4 in blood)

17. Gonadotropines (FSH, LH)

FSH stimulates the maturation of an ovum
each month during a female reproductive
years

Stimulates maturation of sperm in males

Stimulates production of estrogen
hormones

Regulation by negative feedback ( high
concentration of estrogensin blood)

18. LH

Stimulates ovulation and causes
follicular cells to produce
progesterone which stimulates
nidation and mammary gland
development

In males stimulates development of
interstitial cells (Leydig) of testis;
stimulates production of testosterone

19. Somatotropin

Acts directly on some cells to stimulate
growth

Acts indirectly on others to release proteins
(insulin like growth factor I)

Promotes calcium absorbtion from
intestine

Works with insulin and thyroid hormones
to promote collagen synthesis

20. 
Increase the rate at wich cells take up
aminoacids and use them to
synthetise proteins

Stimulate free fatty acid release from
fat cells and glycogen breakdown in
the liver

Stimulate growth to adult size

21. 
Bone and muscle loss associated with
reduced strength in aging may be
due to declining GH after age 50.

At age 30 – body mass: 10% bone,
30% muscle, 20% fatty tissue

At age 75 - body mass: 8% bone, 15%
muscle, 40% fatty tissue

22. Corticotropin(ACTH)

Acts on the cortex of the adrenal gland to
regulate synthesis and secretion of several
of its hormones, especially glucocorticoids

Glucocorticoids stimulate the release of
fatty acids and glucose into the blood and
help the body to resist stress and
inflamation
Regulation by negative feedback ( high
concentration of cortisol in blood)

23. Prolactin

Stimulates milk secretion in
mammary glands previously
prepared for milk production by
other hormones – estradiol,
progesterone, corticosteroids, insulin

24. Beta-lipoprotein

Has been isolated from the anterior
pituitary gland

Endorphins and enkefalins can be
made from it in the anterior pituitary
or in the brain directly

25. Melanocyte stimulating
hormone

Secreted in small quantities by the
intermediate lobe of pituitary gland

Role in skin pigmentation

26. Regulation of the
adenohypophyseal hormones

By neurohormones secreted by hypothalamus
(releasind and inhibiting)

Tropic hormones from the anterior pituitary
regulate other glands such as the thyroid, adrenal
cortex, gonads

Hormones from these glands act by negative
feedback to inhibit the release of both tropic and
hypothalamic hormones

Neural signals elicited by sexual arousal, stress,
anxiety, trauma, variations in the light-dark cycle
and the sucking of a breast-fed infant also
regualte hypothalamus hormones

27. Hypothalamic hormones that
regulate secretion of adenoHY
Hormone Abreviation Function
Thyrotropin releasing
hormone
TRH Stimulates release of
TSH
Corticotropin
releasing hormone
CRH Stimulates release of
ACTH
Gonadotropin
releasing hormone
GnRH Stimulates release of
FSH and LH
Growth hormone
releasing hormone
GHRHH Stimulates release of
GH
Growth hormone
inhibiting hormone
(somatostatin)
GHIH Inhibits release of GH
Prolactin releasing
hormone
PRH Stimulates release of
prolactin
Prolactin inhibiting
hormone
PIH Inhibits release of
prolactin

28. Hormones of the
neurohypophysis

2 chemically similar peptide hormones,
ocytocin and antidiuretic hormone are
called neurosecretions because are
synthetised in hypotalamic neurons
and stored in the neuroHY

When action potentials causes their
release from axons they enter the
blood and act as hormones.

29. Oxytocin

Stimulates contraction of smooth
muscle in the uterus and the
contractile cells around mammary
gland ducts

Is relased during sexual intercourse,
labor, lactation

30. Antidiuretic hormone (ADH)

Also called vasopresine

Prevents excess water loss in urine

In high concentrations constricts
blood vessels

Decreases osmotic pressure and the
urine volume

Increases the blood volume

31. Pituitary disoders
Disorder Possible cause Hormone Excess or
defficiency
Effects
Pituitary
dwarfism
Destruction or
congenital defficiency
of GH production cells
GH defficiencySmall, well proportioned body,
sexual imaturity
Gigantism Pituitary tumor before
adult size is reached
GH excess Large, well proportioned body
Acromegaly Pituitary tumor after
adult size is reached
GH excess Disproportionate increase in
thickness of bones of face,
hands and feet
Panhypopitui
tarism
Tumor or thrombus all defficiencyDepressed thyroid,
adrenocortical and gonad
function
Diabetes
insipidus
Damage to the
hypothalamus
ADH defficiencyExcessive excretion of dilute
urine
High ADH
blood level
Excessive stimulation
of ADH-secreting
neurons or pituitary
tumor
ADH excess Excessively dilute blood and
low sodiun concentration in
plasma

32. Reminder
Glands Hormones Target cells Major effects Negative
feedback
disorders
Adeno
hypophisis
Growth hormone
(somatotropin)
Most cells growth,
maintanence of
adult size, protein
synthesis, release of
fats and glucose
into blood
Blood nutrient
level
Dwarfism,
gigantism,
acromegaly
Prolactin Mammary
glands
Secretion of milk
Follicle stimulating
hormone(FSH)
Ovaries
Testes
Maturation of ova;
production of
estrogen
Maturation of sperm
Estrogen
Inhibin
Luteinizing
hormone (LH)
Ovaries
Testes
Release of ova;
production of
progesterone
Development of
interstitial cells and
production of
testosterone
Progesterone
Testosterone
Adrenocorticotropi
c hormone (ACTH)
Adrenal cortexRelease of
hormones from
adrenal cortex
Cortisol
Thyroid stimulating
hormone (TSH)-
thyrotropin
Thyroid glandSynthesis and
release of T3, T4
T3, T4

33. Reminder
Glands Hormones Target cells Major effects Negative feedback
Neurohypophisis Oxytocin Smooth muscle of
uterus and
mammary ducts
Cause uterine
contraction and
release of milk
Antidiuretic
hormone (ADH)-
vasopresin
Kidney tubules
Smooth muscle of
blood vessels
Water
reabsorbtion
Constrict blood
vessels and raise
blood pressure

34. REFERENCES

Avramescu ET, Rusu L., Ciupeanu – Calugaru D., 2005, Human
Anatomy, Universitaria Publishing House, Craiova,

Bello M., Testing the effects of growth hormone releasing
hormone, Research Resources 9, no 10:1, 1985

Creager J., 1992, Wm. C. Brown Publisher

Lechan, R., Neuroendocrinology of pituitary hormone regulation,
Endocrinology and Metabolism Clinics 16, no 3:475, 1987