3 endocrine

8/2/2019 3 Endocrine

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Anatomy & Histology of Endocrine (3)Our lecture covers two sides 1) Neurohypophysis

2) anatomy of thyroid gland

Notes:* refer to slides as you are reading this sheet.

*feel free to skip any box around since all boxes contain extra information.

*some information written in Arabic because the doctor said it in Arabic.

Warm up:

In last lecture, we have described histological sections as basophilic or although all

the slides were blue in color

In fact most of Dr Darwish's slides are semi thin.

Thick sections (ordinary):1) 5-7 microns in thickness

2) stained with H&E stain

3) histological sections described based on them.

Thin sections: 1-1.5 microns in thickness.

Ultrathin sections: 0.2-1 micron in thickness which is used in electron microscopy

only

Semi thin sections:

1) 1.5-3 microns in thickness

2)don't take H&E stain easily because different chemicals ,procedures ,and materials

used in preparing them , but if you insist ,you can .however, they are not stained

deeply ;needing more time to accept H&E stain; losing their color gradually as they

exposed to light ;should be used immediately after applying antibodies because

flouresenese fades with time

( 2 )

alaninetoludine blue

5

()

.

So the slides appear blue in color.


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Flashback:

Pars Distalis: the most anterior and largest part of anterior pituitary

Pars Tuberalis: surrounds the infundibulum.

-------------

The neurohypophysis is divided into:

Pars Nervosa: the most posterior and largest part of posterior pituitaryInfundibulum: contains the hypothalamo-hypophysial tract.

------------Median Eminence: which is debatable ( ) in classification, some scientistsconsider it part of hypothalamus but others insist that it is a part of posterior pituitary

and we prefer the 2nd

.

Starting offSlide 35 represents a section in a

pituitary gland of an animal

As you see, anterior pituitary is

highly cellular

Pars intermedia are less cellular; and

filled withcolloid-filled cysts. The

cysts are the remainder ofRathkespouch indicating low functionality if

any.

Posterior pituitary with the least

cellularity

The posterior pituitary

1-does not contain secretary cells, so it belongs to nervous system rather than

endocrine.

2-contains secretary neurons .the mother cells of these neurons present in

hypothalamus either in the paraventricular or in supraoptic hypothalamic nuclei.

The mother cells are the sites of activity from which the activity, impulses, and

products start then propagate through axons .any damage occurs at the mother cell,

affects the whole cell.

In CNS the mother cells grouped together in nuclei such as paraventricular &

supraoptic hypothalamic nuclei.
http://en.wikipedia.org/wiki/Colloidhttp://en.wikipedia.org/wiki/Colloidhttp://en.wikipedia.org/wiki/Cysthttp://en.wikipedia.org/wiki/Rathke%E2%80%99s_pouchhttp://en.wikipedia.org/wiki/Rathke%E2%80%99s_pouchhttp://en.wikipedia.org/wiki/Rathke%E2%80%99s_pouchhttp://en.wikipedia.org/wiki/Rathke%E2%80%99s_pouchhttp://en.wikipedia.org/wiki/Rathke%E2%80%99s_pouchhttp://en.wikipedia.org/wiki/Rathke%E2%80%99s_pouchhttp://en.wikipedia.org/wiki/Cysthttp://en.wikipedia.org/wiki/Colloid


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3- The most numerous cells in the posterior pituitary are called pituicytes, these cells

resemble astrocytes.

4-the nerve fibers are so special becauseA) They don't terminate at target organ instead they terminate diffusely around the

fenestrated capillaries which are openings in endothelium; thus, their secretions are

Distributed to the general circulation.

B) The secretary vesicles distributed all over the neuron unlike the usual neurons inwhich the secretary vesicles restricted to the bodies!

C) Their secretions are regular in shape indicating a presence of membranes about

them.

Herring bodies: are eosinophilic dilatations in terminal of axon; and containnumerous membrane-enclosed vesicles, so they are regular in shape, but not in size.

The neurons present in the posterior pituitary secrete two hormones produced in the

hypothalamus;Anti-diuretic hormone (ADH) also called vasopressin, and oxytoxin. These

hormones are transportedaxonally into the pars nervosa and are stored in axonal dilations called neurosecretory

bodies or Herring

Bodies.

cells of CNS

neurons

(function cells)

supporting cells

(glial cells)

more in number

astrocytes

form BBB

(support&protection)

oligodendrocytes

equivilent to schwan

(in periferal (PNS

microgialphagocytosis

(defens &

protection)

epidendimalsecrete CSF


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Nerve impulses along the axons trigger the release of peptides from Herring bodies

for uptake by the fenestrated capillaries of the pars nervosa, and the hormones are

distributed to the general circulation.

ADH (Vasopressin)

Most ADH is released from supra optic nuclei in the hypothalamus. ADH facilitates

reabsorption of water

From the distal tubules and collecting ducts of the kidney by altering the permeability

of cells to water. Itis released in response to decreased blood pressure and leads to increased water

retention. ADH helps

regulate the osmotic balance of body fluids.

If there hadn't been ADH at all, one would have had to drink huge amount of water

releasing a huge amount of urine spending his life in bathroom.

Luckily, ADH nowadays prepared on commercial base; moreover, the incidence of

diabetes insipidus ( ( is relatively low.

After major surgeries, in appropriate ADH response takes place in spite of the normallevel of ADH, so those patients have to undergo dialysis.

Oxytocin

Most oxytocin is released from paraventricular nuclei in the hypothalamus. Itpromotes contraction of the smooth muscles; especially, the uterus and themyoepithelial cells of the breast aiding in the release of milk, and returning the uterus

close to normal size (7.5 cm in length); by the way, nothing returns back 100% but to

acceptable extent, preventing huge amount of blood lose; therefore, the probability of

having Puerperal fever or childbed fever ( ).The most powerful stimulus for oxytocin is suckling

The substance oxytocin, which is present in the date, is used in modern medicine to facilitate birth.

In fact, oxytocin means "rapid birth." It is also known to increase levels of mother's milk after birth

There is considerable wisdom in the way that Allah recommends Maryam to eat this fruit. The date

is an excellent choice of food for the pregnant women and for those who have just given birth. This

is a widely accepted scientific fact.


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Its name is derived from the

Greek word hyoeidesmeaning

"shaped like the letterupsilon"()

Thyroid

Thyroxin abuse

*to lose some weight; unfortunately, increase apatite!!!

*students take small dose to become alert; unfortunately, without focusing; moreover,

increasing sweat, apatite, and nervousness.

Thyroid hormone is important regulators of overall basal metabolic rate; it affects

both turnover and growth.

Hyoid bone situated superiorly

The only bone without bony articulation

Position and components

10 grams in weight

Has basically 2 lobes The isthmus lies on tracheal rings 2, 3

and 4 connecting the two lobes.

The apex of each lobe rests on thethyroid cartilage and reaches its

oblique line which separates the

anterior & the posterior parts of the

lamina, so we consider it as a land

mark.

Small (but maybe variable in length)pyramidal lobe projects upward from

thyroid = thyreo + eides Greek,

like a door-shaped (shield) , thyra Greek, door

The thyroid cartilage was named first. It shields thevocal cords of the larynx. This cartilage

(cartilago Latin, gristle) sticks out in front of the neck

and is called the Adam's apple. A thyreos was an

ancient Greek army shield shaped like a door (thyra),

with a notch at the top for the soldier's chin. Gently

feel the top of your Adam's apple. It has a notch.

Thyroid is a fitting name, isn't it?

Alertness: being mentally quick, active, and keenly aware

of the environment.
http://en.wikipedia.org/wiki/Upsilonhttp://en.wikipedia.org/wiki/Upsilonhttp://en.wikipedia.org/wiki/Upsilonhttp://en.wikipedia.org/wiki/%CE%A5http://en.wikipedia.org/wiki/%CE%A5http://en.wikipedia.org/wiki/%CE%A5http://en.wikipedia.org/wiki/%CE%A5http://en.wikipedia.org/wiki/Upsilon


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the left lobe in 40% of cases (but may from the right lobe) reaching the oblique

line in some cases.

The pyramidal lobe is connected to the hyoid bone by a fibrous band that maycontain a few smooth muscle fibers which make up the muscle named the

Levator Glandulae Thyroidae.

The base of thyroid reaches the 6th tracheal ring. The thyrohyoid membrane situated between hyoid bone and thyroid cartilage

havinga) superior horn which gives attachment to the lateral hyothyroid ligament

(membrane).

b) Inferior horn for articulation with the side of the cricoids cartilage

Thus thyroid is widely extended

Surgery room

The patient is placed supine (face up) on the operating room table. A folded towel is

placed under the neck to hyperextend the neck. The top part of the table is elevated so

the patient is in a slightly reclining position. The head must be perfectly aligned with

the body so a symmetrical incision is made by the surgeon. The incision is made

transversely (side to side) about two fingers breadth above the sternal notch. It should

be placed in a skin crease if possible for best cosmetic result. Most commonly, a

slight indentation is made in the skin by using a heavy silk suture to compress the

skin

For thyroidectomy (removal of the thyroid gland), the most important are the

relations.

Surfaces and relations

Superficial surface:

Covered by skin, superficial fascia including the platysma muscle which isredundant in elderly, and described as the mystery of smile by Leonardo da

Vinci. The anterior border of the sternocleido mastoid.

The pretracheal fascia. Stern hyoid

Omohyoidomo:shoulder The infrahyoid muscles, except the thyrohyoid.

Medial surface:

Thyroid and cricoid cartilages:
http://en.wikipedia.org/w/index.php?title=Hyothyroid&action=edit&redlink=1http://en.wikipedia.org/wiki/Ligamenthttp://en.wikipedia.org/wiki/Cricoid_cartilagehttp://en.wikipedia.org/wiki/Cricoid_cartilagehttp://en.wikipedia.org/wiki/Ligamenthttp://en.wikipedia.org/wiki/Ligamenthttp://en.wikipedia.org/w/index.php?title=Hyothyroid&action=edit&redlink=1


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Regardless of the differences among sexes, the cricoid cartilage is the only cartilage

with the shape of a complete circle in the human body. It is very similar to the

tracheal rings except that they are C shaped with a posterior opening, not complete

circles.

Trachea and esophagus which contain in between the tracheoesophagealtract.

The external laryngeal and the recurrent laryngeal nerves.

Cricothyroid cartilage inferior pharyngeal constrictor muscle :

A) Cricopharyngeal muscle which continues as esophagus; this muscle is the only

muscle in the human body that is in a contracted state at rest, in order to

keep air from entering the esophagus. When swallowing, this muscle relaxes,

allowing the morsel () to enter the esophagus, after which it returns to itscontracted state.

In order for this muscle to perform its function which requires speedy contraction, it

is a skeletal muscle and not a smooth muscle.

b) Thyropharyngeal muscles: attach the pharynx from one side then diverged into

1) Superior which attaches to the base of skull

2) Middle which attaches to hyoid bone3) inferior which attaches to thyroid and cricothyroid cartilage

Posterior surface:

Common carotid artery in front of the Longus Colli muscle.

The parathyroid glands.The inferior thyroid artery.

Note:

*take care of parathyroids because destruction of them= titanic .

* this region is extremely vascular .

:

Written by Ihmeidan's keyboard

3 endocrine

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