Histology

Question 1

Define trachea?

Answer 1

1 rigid tube 10cm long
2 extends from The larynx to the upper part of the thorax where it bifurcates to right and left primary bronchi

Question 2

Wall of trachea?

Answer 2

Is supported by 16 to 20 C shaped rings of hyaline cartilage joined at the free ends by (dense ct) which is continuous with the perichondrium of each cartilaginous ring
طبعًا فيه defecated من ورا بعضلة اسمها trachealis muscle عبارة عن سموث مسل مرتبطة بال oesophagus وهذا كويس عشان ناكل مرتاحين

Question 3

Describe the three layer of trachea in general?

Answer 3

Mucosa: Epithelium + CT (lamina propria)
Submucosa: loose ct + seromucous gland
Adventitia: outer layer + hyaline cartilage

Question 4

Describe the mucosa of trachea?

Answer 4

زي ما قلنا حاجتين
Epithelium: pseudo stratified columnar
ciliated epithelium with goblet cells
Lamina propria: loose ct rich in ct cells + lymphatics + blood vessels + elastic fibres and membrane وهذا الممبرين يفصل الطبقة ذي عن اللي بعد شوي نتكلم عنها submucosa

Question 5

Describe the five types of cells in Respiratory epithelium

Answer 5

1. Ciliated Columnar Cells (the most abundant, each with 250-300
   cilia on its apical surface)
2. Goblet Cells (e also numerous, apical domains filled with
   granules of mucin glycoproteins)
3. Pyramidal Basal Cells (mitotically active stem)
4. Brush cells (chemosensory receptors)
5. Small granule cells (or Kulchitsky cells) Neuroendocrine Cell
   اقسم بالله اسهل شيء بالعالم

Question 6

Describe submucosa structure?

Answer 6

نفس ct structure of mucosa بالضبببببط
المميز فيها seromucos secreting glands

Question 7

Describe adventitia layer?

Answer 7

هي ٢ بارت
1 cartilaginous layer layer of ct contain C shaped hyaline cartilage انعاد نفس الكلام ان الفراغ يتغطى بتركيالس مسل
2 adventitia loose ct

قالت اهم شيء لما أعطيكم سكشن يكون فيه كارتلج + respiratory epi عشان نقول ان هذا المقطع في القصبة الهوائية

Question 8

We finish trachea
Starting with??? Bronchial tree

Answer 8

Primary (main) (extra pulmonary) نفس الشيء بالضبط ماعدا أنها راح تكون completed cartilaginous ring
Secondary (lobar) (intrapulmonary bronchi): هنا بيكون نفس الترتيب ماعدا ان submucosa replaced by muscle
Mucosa the same ✅
Muscle: ⭕️ smooth muscle fibers
Adventitia اهم شييييييييء قالت irregular plate of hyaline cartilage, lymph follicles & glands
Tertiary (segments) same with lobar

Question 9

Describe bronchioles?

Answer 9

برضو نفس الشيء
٣ طبقات
Mucosa
Muscle: well developed حلوة ✅
Adventitia no❌❌❌❌❌❌
الفرق كل ما نزلنا تحت تقل cilia and goblet cells وتزيد elastic fibres
طيب مين أولى يختفي؟ goblet cells
لان لو اختفت السيليا اللي تحرك افرازات القوبلت راح يصير trapping the body can’t move it and secret it outside

Question 10

What’s Clara cells? (Club cells, bronchial exocrine)

Answer 10

Start in the end of conducting zone and at the beginning of respiratory zone
LM/ Columnar non-ciliated cells with rounded apex & the
nucleus is rounded and central
EM/ The apical cytoplasm contains dense secretory
Granules, Golgi complex and long mitochondria & sER
اهم شيء فيها أنها تصنع protective proteins بس تحتاج طاقة وهذا يفسر وجود المايتوكندريا
sER مهمة في إيش؟ أنها تسوي ديتوكس للهواء اللي داخل
وزيادة لها مكنزم في regeneration لان لها stem cells

Question 11

Describe respiratory bronchioles?

Answer 11

نفسسسسس التركيب حق terminal bronchiole except
INTERRUPTED by numerous alveoli
بتكون في البداية ciliated cuboidal & Clara cells وكل ما ننزل تحت تختفي السيليا ذي
ومهم * ماعاد فيه قوبلت خلاص ولى زمنها
Smooth muscle & elastic CT مهمة عشان تدعم جدار التنفس
Terminate at alveolar duct

Question 12

سؤال وش يفرق respiratory bronchioles of alveolar duct

Answer 12

نووع الخلية !! Squamous cells
في البداية تكون فيها Lamina propria surrounds the alveoli formed of
delicate C.T. and smooth muscle fibers (sphincter
regulating the diameter of opening of each alveolus) سموث مهمة في أنها تنظم تدفق الهواء عن طريق التحكم ب diameter
بس كل ما ننزل لتحت نفقد السموث ذي ويحل محلها elastic وتعطي شعور أنها سموث ليه؟ لأنها recoil and give sphincter like structure
NO smooth muscle
Terminate at common space (atrium) جيران فاتحين على بعض ويتواصلون مع alveolar sacs

Question 13

What is alveolar sacs and alveoli ???

Answer 13

Alveolar sac: is cluster of alveoli
Lined mostly by (alveolar
squamous epi)

Question 14

What’s the alveoli?

Answer 14

Basic structural and functional units of the lung
 Rounded or oval
It is the site of exchange
 They are responsible for the spongy structure of the lung.
 wall lies between neighboring alveoli is termed interalveolar
septum.
The alveoli are Lined by alveolar epithelium

Question 15

Define type 1 pneumocystis?

Answer 15

Number: 95% of the alveolar epithelium
• LM: flat simple squamous epithelium less than 0.2μm with
slightly thickened area containing flat nuclei
• EM: Golgi, mitochondria, ER and nucleus are grouped in wide
area
- Attached by occluding junctions to each other and to Type II pneumocystes

have thin basement that fuse with the basement membrane of
the capillary
function:
• Gas exchange
• Share in formation of blood air barrier

Question 16

And what about type 2 pneumocystis

Answer 16

Number: 5% of the alveolar epithelium
• LM: cuboidal cells with central rounded nuclei
at the angle of the alveolus
EM:- thicker than type 1 with rounded apical surface that is covered Short
microvilli
 Joined with type I By tight junction
 Cytoplasm: Well developed golgi
complex, RER and mitochondria
& lamellar bodies

lamellar bodies: electron dense lamellated granules
rich in phospholipid and surrounded by membrane
Functions
• Have the capacity to divide and replace type I and
type II
• secretion of phospholipid substance (pulmonary
surfactant)

Question 17

What is inter-alveolar septum?

Answer 17

def. it is the space between alveoli
Formed of
• Alveolar epithelium on either side
• Continuous capillary network
• C.T. (reticular and elastic fibers)
• Fibroblast, macrophages & mast cells
• Basement mebrane of both (alveolar epith. & blood capillary)

Question 18

Alveolar pores is interrupte?? Pores of kohn

Answer 18

The interalveolar Septa

importance:
- Connect adjacent alveoli
- Equalize air pressure

Question 19

Describe the origin, site, and the cytoplasm of alveolar macrophage?

Answer 19

From monocyte

in the interstitium, on the surface of the alveoli, or
in the alveolar lumen

contains lysosomes phagocytosed
bacteria, foreign material, carbon or dust
عندنا ٢ تايب وحده إذا تتكون من كربون وغبار نسميها خلية الغبار
وحده نسميها هارت فيلير لان تأخذ صبغة الRBCs

Question 20

Describe the layer in blood air barrier

Answer 20

Air in alveoli is separated from blood in capillaries by:
1- The surfactant layer on the alveolar surface
2- The cytoplasm of the alveolar cells (type I).
3- The fused basal laminae of type I cell & endothelial cells of the
capillary.
4- The cytoplasm of the endothelial cells

Question 21

What’s pleura? And describe its microscopic structure.

Answer 21

The serous membrane covering the lung.
Consists of two layers; parietal & visceral which are
continuous in the hilum.
A cavity between the two layers called pleural cavity, &
contains fluid that acts as a lubricating agent

Both membranes are composed of mesothelial (Simple
Squamous epithelium) cells resting on a fine CT layer
(collagen & elastic fibers as well as few macrophages &
fibroblast