Tissues And Organs Flashcards
(41 cards)
What is a tissue?
A group of cells (often very similar in shape) that work together to carry out the same function.
Tissues are the building blocks of organs and systems in the body.
What is an organ?
A group of tissues that work together to carry out one or more functions.
Organs are composed of different types of tissues that perform specific tasks.
What is an organ system?
A group of organs that work together e.g. digestive system.
Organ systems coordinate multiple organs to accomplish complex functions.
Name the 5 layers of the ileum, visible in a cross section diagram (FROM THE OUTSIDE IN)
• serosa
• muscularis externa
• submucosa
• muscularis mucosa
• mucosa
These layers perform various functions essential for digestion and absorption.
What is the function of the serosa?
An outer layer of connective tissue which provides a very thin protective and supportive lining for the alimentary canal.
The serosa helps to reduce friction between the digestive organs and surrounding structures.
What is the function of the muscularis externa?
Peristalsis: Contractions of the longitudinal muscles cause pendular movements. Contractions of the circular muscles cause local constrictions and help push food along the gut in a series of peristaltic waves.
This layer is crucial for the movement of food through the digestive tract.
What is the function of the submucosa?
This layer is mainly composed of connective tissue but also contains many blood vessels and lymphatic vessels to transport absorbed food products.
The submucosa provides support and nourishment to the surrounding tissues.
What is the function of the muscularis mucosa?
This thin layer of muscle has small strands of muscle extending upward into each villus, and when they contract they waft the villi. This movement of villi improves contact with the digested food.
The muscularis mucosa enhances nutrient absorption by increasing the surface area of the intestinal lining.
What is the function of the mucosa?
It is the layer in contact with digested food in the gut lumen. It is lined with columnar epithelial cells and it has a hugely increased surface for absorption due to villi and microvilli on the folds.
The mucosa plays a vital role in digestion and absorption of nutrients.
Name the 5 layers of the ileum
What are the cells called that line the external surface of the villi?
Columnar epithelial cells
These cells are specialized for absorption in the intestinal lining.
What adaptations do columnar epithelial cells have for the absorption of digested food?
- Increased surface area due to large number of microvilli (brush border)
- Rich in mitochondria for ATP production for active transport
- Increased number of membrane protein carriers for facilitated diffusion
These adaptations enhance the efficiency of nutrient absorption.
How are digested food molecules absorbed into the villi and then into the blood?
Glucose and amino acids are absorbed by active transport into epithelial cells then into capillaries by facilitated diffusion
The hepatic portal vein carries these nutrients to the liver.
What are goblet cells and where are they found?
Goblet cells are found between columnar epithelial cells and they secrete mucus, which acts as a slimy protective layer, facilitates movement of food and protects the epithelial cells from digestive enzymes
Mucus aids in lubrication and protection of the intestinal lining.
Fill in the blank: The surface area of columnar epithelial cells is greatly increased by the presence of numerous _______.
microvilli
Microvilli form a brush border that enhances absorption.
What is the role of mitochondria in columnar epithelial cells?
They are the sites of aerobic respiration where ATP is made
ATP is essential for active transport processes.
How do fatty acids and glycerol move into the epithelial cells?
By facilitated diffusion, they then move into lacteals
After entering the epithelial cells, they move into lacteals for transport in the lymphatic system.
True or False: Some fats are taken up by pinocytosis.
True
Pinocytosis is a form of endocytosis that allows cells to take in fluids and small particles.
What are Crypts of Lieberkuhn?
Intestinal glands found in the tissue between villi
Where are Crypts of Lieberkuhn located?
In the tissue between villi
What is the function of the cells at the bottom of the Crypts of Lieberkuhn?
Continually dividing by mitosis to produce new cells
What happens to the new cells produced in the Crypts of Lieberkuhn?
They move up the villi to replace old ones
What are Paneth cells?
Cells found at the base of the crypts with an antimicrobial function
Where are Paneth cells located?
At the base of the Crypts of Lieberkuhn
