Tissues and Organs- Topic 7 Flashcards
what are tissues made of?
-cells that perform a common function
what do tissues combine to form? give an example.
-an organ e.g. muscle, connective and nerve tissue all work together in the heart
what is an organ?
-a group of tissues that carry out a particular function
where is the ileum located?
-it is part of the small intestine following the duodenum
how many layers are in the ileum and what are their names?
-5
-mucosa
-muscularis mucosa
-submucosa
-muscularis externa
-serosa
where is the mucosa layer located and what adaptation does it have?
-innermost wall of small intestine
-thousands of villi which increase the surface area for absorption
how many features does the mucosa have and what are their names?
-columnar epithelium
-crypts of Lieberkühn
-capillaries and lacteals
-microvilli
what type of cells are columnar epithelium and what is another name for them?
-glandular epithelium cells are also known as goblet cells
what do goblet cells do? why is this important in the columnar epithelium ?
-they secrete large amounts of mucus and digestive enzymes
-the mucus acts as a lubricant and it protects the gut wall from digestion by its own enzymes
what is the job of the crypts of Lieberkühn?
-narrow crevices found at the base and between the villi
-the crevices are formed from epithelium and Paneth cells
what are the job of Paneth cells?
-they secrete digestive enzymes and fluid that has antimicrobial action which protects stem cells dividing at the bottom of the crypts
what are the jobs of the capillaries and lacteals in the mucosa layer?
-each villus contains a blood capillary which absorbs glucose and amino acids by active transport which requires energy
-lacteals absorb fatty acids and glycerol by pinocytosis
-vitamins and minerals are absorbed by diffusion in to the blood capillary
what is the job of the muscularis mucosa layer?
-layer of smooth muscle which moves the villi in a wave like fashion to increase its contact with food
what is the job of the submucosa layer?
-contains blood and lymph vessels and connective tissue for support
what is the job of the muscularis externa layer?
-circular and longitudinal contractions (peristalsis) churns up food and moves it along the gut
what is the job of the serosa?
-layer of connective tissue that provides protection and support
what is the organ in a plant?
-the leaf
the leaf has many adaptations for what purposes?
-maximizing photosynthesis and minimizing transpiration water loss
what is the job of the upper epidermis and cuticle?
-waxy cuticle protects against water loss and damage from pests
-upper epidermis is transparent allowing maximum light penetration for photosynthesis
what is the job of the palisade mesophyll cells?
-packed arrangement allows maximum light absorption, with many chloroplasts which are the site of photosynthesis
-chloroplasts can move around the cells so that they can get the most light
what is the job of the spongy mesophyll?
-loose arrangement which create air spaces for diffusion of gases
-they also have some chloroplasts
what is the job of airspaces in the leaf?
-allows gases and water vapour to diffuse quickly throughout the leaf
what is the job of the vascular bundle?
-xylem transports water and inorganic ions to the leaf
-phloem transports sugars produced in photosynthesis away from the leaf
what is the job of the lower epidermis and cuticle in the leaf?
-the waxy cuticle reduces water loss and damage from pests
what is the job of the stomata in the leaf?
-they are openings on the lower leaf surface which allow gas exchange into and out of the leaf
-found mostly on the lower epidermis
what are the job of the guard cells in the leaf?
-control the opening and closing of the stomata
-they close the stomata at night to reduce water loss by transpiration
