PRESICE AND SHORT NOTES TO BE ABLE TO CRACK NEET EXAM COMING FROM AN MBBS STUDENT. CAN BE USEFUL IN BOARD EXAMS AS WELL. INFORMATION FROM AAKASH COACHING CENTRES AND NCERT TEXTBOOKS HAVE BEEN ADDED.
Structural org in animals
Intro:
➔ The term tissue in animals - Bichat and in plants - N.Grew.
➔ Study of tissues - histology, termed by Mayer.
➔ Tissues first evolved in Coelenterates. - cels from same origin and specific function
● All complex animals consist of four basic types of tissues : Epithelial, connective, muscular and
neural tissue :
○ Epithelial tissue :
■ Origin : ectoderm, mesoderm, endoderm
■ Main functions : protection, secretion, absorption, excretion, and reproduction
○ Muscular tissue :
■ origin is mesoderm
■ main functions : movement of body parts and locomotion
○ Connective tissues :
■ origin is mesoderm
■ main functions : attachment, support, storage, protection and transport.
○ Nervous tissues :
■ origin is ectoderm
■ main functions : control and coordination by nerve impulse conduction
Epithelial tissues :
● First termed by Ruysch
● Closely arranged in one/more layers with very little intercellular material.
● Protect surface of organs and form glands
● First formed Tissue in the embryo
● Avascular tissue
● The basal Surface lies in contact with a delicate noncellular layer called basement membrane.It
provides elastic support and also anchors the epithelial tissue to the underlying connective tissue
for obtaining nutrients. {lacks blood vessels}
● Basement membrane: It is an outer thin layer composed of Mucopolysaccharides and glycoproteins,
both secreted by epithelial cells.
● Reticular lamina: It is an inner thick layer composed of collagen or reticular fibres of the underlying
connective tissue.
● Function : Provides covering / lining to for some parts of body - 2 types : simple and compound
epithelium :
○ Simple epithelium : uni layered - gives lining to tubes, ducts, glands - 3 types :
■ Squamous epithelium : made of single thin layer of flattened cells :
● AKA pavement epithelium and tessellated epithelium.
● Found in : walls of blood vessels [endothelium], air sacs of lungs, bowman's
capsule [endoderm], outermost lining of frog and ovary [ectoderm], lining of
body cavities [mesothelium and peritoneum], lymph vessels, loop of henle
● Functions: forming diffusion boundary, protection, filtration, excretion,
gaseous exchange and secretion of coelomic fluid.
■ Cuboidal epithelium : cuboidal single layered cells :
● AKA brush-bordered cuboidal epithelium,
● Found in duct glands, tubular parts of nephrons in kidney -> PCT (microvilli),
thyroid follicles, ovaries and testes [germinal epithelium - produce gametes
and ovas and found in gonads]
● Functions: secretion,absorption, excretion, - microvilli present on the free
surface increase absorption surface area.
■ Columnar epithelium : tall and slender cells - nuclei at base :
, ● Present in : intestine, lining of stomach, gallbladder, bile duct when bearing
microvilli are called brush-bordered columnar epithelium
● Function: absorption and secretion.
■ BEARS CILIA : columnar or cuboidal cells with cilia - ciliated epithelium :
● Function : move particles / mucus in specific direction over epithelium
● Present in : inner lining of hollow organs - fallopian tubes (columnar) and
bronchioles (cuboidal).
● Cells secreting mucus - goblet cells. Goblet cells+underlying connective
tissue = Mucosa or mucous membrane. Helps in movement of mucus, urine,
eggs, CSF (cerebro-intestinal fluid in brain), in particular direction.
■ Columnar or cuboidal cells SPECIALISED FOR SECRETION - Glandular
Epithelium : may be made up of cell tissue or organ. Every gland is called acinar
cell. Types of glands:
● BASIS OF Cell number:
○ Unicellular glands: isolated single cells - in goblet cells of alimentary
canal.They secrete mucous[a proteinaceous and slimy substance] and
are called mucocytes.
○ Multicellular glands: cluster of cells - always consisting of ducts and
secretory parts - Found in salivary glands, sebaceous glands, sweat
glands, gastric gland, thyroid gland.
● Basis of mode of pouring of secretion :
○ Exocrine glands: secrete to the exterior body surfaces, pass secretion
through ducts or poured directly over the substrate. Found in oil
glands,mammary glands,salivary glands,etc.
○ Endocrine glands: ductless glands, secrete directly into the fluid
(blood and lymph). They carry hormones towards target organs -
Found in thyroid, pituitary, adrenal, hypothalamus,etc.
○ Heterocrine or Mixed glands: has parts of both exocrine and endocrine
and follows their functions - Found in pancreas and gonads [testes
and ovaries]
○ Compound epithelium :
■ Multi layered - limited role in secretion and absorption - provides protection against
chemical and mechanical stresses
■ Present in dry surfaces of skin, moist surface of buccal cavity, pharynx, inner lining
of salivary gland ducts, pancreatic ducts.
■ Held together with little intercellular material
Cell junctions :
● Provides structural and functional like between individual cells
● 3 types :
○ Tight junction : stop substance from leaking
■ Pseudo stratified epithelium, cells are columnar and unequal in size,Nuclei is oval
and at different level, looks like multiple layers, has two types : Pseudo stratified non
ciliated columnar epithelium in urethra of human male and large ducts of parotid
salivary glands, pseudo stratified ciliated columnar epithelium in the trachea and
large bronchi, Functions:protection, secretion, and movement of secretion.
3.Mode of secretion:
Holocrine glands: In holocrine glands (e.g., sebaceous gland), the product of
secretion is shed with the whole cell leading to its destruction.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller itsshazmeen. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.49. You're not tied to anything after your purchase.
