Chapter 6 - Tissues And Organs Flashcards
(24 cards)
What is a tissue?
An amalgamation of cells that all perform the same function
What is an organ?
A body part composed of several tissues grouped together to perform an overall function
What is a organ system?
Is a group of organs working together towards a larger goal (digestive system)
What is the ileum?
The region of the small intestine where digestion is completed and where most absorption of the products of digestion occur?
What provides the large surface area for the ileum?
Folds in the inner surface of the intestinal wall.
Projections called villi.
Microscopic projections called microvilli.
What are the layers of the ileum from the outermost to innermost?
Serosa, Muscularis externa, Submucosa, Muscularis mucosa, Mucosa.
What are the layers of the ileum from the innermost to outermost?
Mucosa, Muscularis mucosa, Submucosa, Muscularis externa, Serosa
What are contained within the mucosa?
The columnar epithelium,
Goblet cells,
Villi,
Crypts of Lieberkühn.
What is the columnar epithelium?
Has column shaped cells and lines the intestine. On there surfaces they have microvilli, forming a brush border. The cells of epithelium are short lived. Some substances are taken up partly by diffusion, partly by active transport, others are taken up by pinocytosis.
What are goblet cells?
These cells secrete mucus. It protects the epithelium from the action of digestive enzymes and lubricates the lining as solid material is pushed along
What are villi?
Finger like projections that increase the surface area for the absorption of the products of digestion. It contains blood capillaries into which amino acids and monosaccharides are absorbed and lacteals into which fats are absorbed.
What is the Crypt of Lieberkühn?
Stem cells that line the bottom of the crypts at the base of villi. They are in state of continuous division, new cells are continuously being pushed up by the division of cells deeper down. Paneth cells are also present and they protect the dividing cells form microbes.
What is the muscularis mucosa?
The muscle fibres contract to cause movement of the villi, so improving contact with the products of digestion.
What is the submucosa?
It is largely composed of connective tissue and contains many blood vessels and lymphatic vessels, that transport absorbed food products.
What is the muscularis externa?
Consists of an outer layer of longitudinal muscle and an inner layer of circular muscle. Contractions of the longitudinal causes pendular movement of the gut, while the circular muscle may result in local constrictions, both of which churn the food. Coordinated contractions push the food along by peristalsis.
What is the serosa?
This outer layer of connective tissue provides a very thin protective and supportive lining fir the alimentary canal.
What are the layers in a plant cell from outermost to innermost?
Waxy cuticle, Upper Epidermis, Palisade Mesophyll, Spongy Mesophyll, Xylem vessels, (inside Spongy Mesophyll) Phloem sieve tubes, (inside Spongy Mesophyll) Lower Epidermis, Stomata.
What is the upper epidermis?
Protective layer that lacks chloroplasts. They secrete a waxy cuticle that provides waterproofing and reduces water loss.
What is the palisade mesophyll layer?
In the upper half of the leaf, has layers of tightly packed cells, each with lots of chloroplasts. It is adapted for maximum light absorption. Main photosynthetic region.
What is the spongy mesophyll layer?
Is in the lower half of the leaf, contains large air spaces. Gaseous exchange between air spaces and atmosphere can take pace via stomata. Also contains chloroplasts.
What is the xylem vessels?
They supply the leaf with water and inorganic ions.
What are the phloem sieve tubes?
They transport sucrose away from the leaf
What is the lower epidermis layer?
They lack chloroplasts. The cuticle secreted on the lower surface is thinner than that of the upper surface since it is not directly exposed to the sun
What is the stomata?
They are within the lower epidermis. There are many of them which allow gaseous exchange. They also allow water vapour to easily diffuse out of the leaf. Each stoma(sing.) is surrounded by a pair of guard cells, which cause it to close at night and so water loss by transpiration is minimised.
