Test: Protective Tissues In Animals - Class 9 MCQ

Columnar epithelium is located in thyroid vesicles... more , gonads eg. ovaries and testes and sweat and salivary gland thus secreting thyroxine , estrogen , sweat and saliva so performing secretion and glandular epithelium is located in intestine secreting mucous it is the modified form of columnar epithelium thus secreting some of its products also so both perform secretion.

Epithelial Tissue Involved in Goitre:
The epithelial tissue involved in goitre is the Glandular epithelium. Here's why:
- Goitre is characterized by the enlargement of the thyroid gland, which is a part of the endocrine system.
- The thyroid gland is composed of follicles that produce, store, and release thyroid hormones.
- The cells lining the follicles are composed of glandular epithelium.
- Glandular epithelium is specialized for secretion and is found in glands throughout the body.
- In the thyroid gland, the glandular epithelial cells produce and secrete thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3).
- When the thyroid gland is not able to produce enough thyroid hormones, it can lead to an increase in the secretion of thyroid-stimulating hormone (TSH) by the pituitary gland.
- This excess TSH stimulates the growth and enlargement of the thyroid gland, resulting in goitre.
- The swelling in the throat region is caused by the increased size of the glandular epithelial cells and the increased blood flow to the enlarged thyroid gland.
In conclusion, the glandular epithelium is involved in goitre as it is responsible for the production and secretion of thyroid hormones, which can lead to the enlargement of the thyroid gland when there is an imbalance in hormone levels.

Name the region where epithelial tissue is not found.
Epithelial tissue is a type of tissue that covers the surfaces of organs, lines body cavities, and forms glands. It is found throughout the body and serves various functions depending on its location. However, there are certain regions where epithelial tissue is not found. Let's explore these regions:
1. Lung alveoli:
- Lung alveoli are tiny air sacs located in the lungs.
- They are responsible for gas exchange, allowing oxygen to enter the bloodstream and carbon dioxide to be removed.
- The walls of lung alveoli are composed of simple squamous epithelium, which is a type of epithelial tissue.
2. Skin:
- The skin is the largest organ of the body and serves as a protective barrier against the external environment.
- It is composed of multiple layers, including the epidermis and dermis.
- The epidermis, the outermost layer of the skin, is primarily made up of stratified squamous epithelium.
3. Lining of mouth:
- The lining of the mouth is composed of oral mucosa, which is a type of epithelial tissue.
- It covers the inner surfaces of the mouth, including the cheeks, lips, tongue, and gums.
4. Heart muscle:
- The heart is a muscular organ responsible for pumping blood throughout the body.
- The walls of the heart are composed of cardiac muscle tissue, not epithelial tissue.
Therefore, epithelial tissue can be found in the lung alveoli, skin, and lining of the mouth, but not in the heart muscle.

Squamous Epithelium – These are thin, flat cells that are closely packed. The squamous epithelial cells line the cavities of the mouth, oesophagus, alveoli, and blood vessels. This tissue gives protection against mechanical injury and also blocks the entry of germs. If the squamous epithelium is arranged in many layers, it is a compound squamous tissue called the stratified squamous epithelium. We find these kinds of tissues in the skin and also the lining of the oesophagus.

It is so because it is present in epithelial tissue just under the epithelium and if it would not be present then there would be no one to anchor down the epithelium and also there would be absence of mechanical barrier.