Functioning systems Flashcards
AOS 2 (33 cards)
Where does most photosynthesis occur?
Palisade layer of mesophyll
Where does gas exchange of CO2 and O2 occur?
Stomata (openings on the lower epidermis)
What is transpiration?
Transpiration is the movement of water and minerals up the stem of a plant. Specifically the loss of water vapour from the plant via the stomata in the leaves.
How does transpiration occur?
- The stomata opens and the gases diffuse out of the leaf when the sun shines.
- Water vapour moves through the stomata and into air.
- Water evaporates from mesophyll cell and out to moisten the wall to replace the water lost
- Water moves into mesophyll from xylem to provide water
- When water moves out of xylem its also sucks in from xylem and into leaf.
What does the xylem do?
xylem transports minerals and water from the roots to the photosynthetic areas of the plant (tranpiration vacuum)It’s absorbed from the root hairs and through the cortex into xylem in vascular tissue. Xylem is made of dead hollow cells and provides internal support.
What does phloem do?
Phloem transports sucrose (packaged glucose via photosynthesis) and hormones through the living seive cells to the non photosynthetic parts (sinks) known as translocation. Sugars are either stored as starch or broken into monosaccharides and metabolised for growth.
How does translocation occur?
Translocation occurs via active transport and osmosis. Atp energy for active transport is provided by the companion cells and osmosis occurs due to the high concentration of sugar. When sugar is transported out of the phloem and into the non photosynthetic parts the water returns to the xylem.
What do animals need for digestion?
What is the mouth cavity?
The mouth cavity is the entry for food, the upper and lower jaw to chew food and tongue catches and manipulates the food into a bolus.
What is the salivary gland
The salivary gland secretes saliva, lubricates food and the salivary amylase breaksdown the starch and carbs.
What is the oesophagus?
The oesophagus is the tube that transports food from the mouth to the stomach by peristalsis. The food is allowed to go down to the stomach by the epiglottis giving entry.
What is peristalsis
Peristalsis is the involuntary action of muscle constriction and relaxation to move food down the digestive tract.
What is the stomach?
The stomach is an organ which can expand from empty volume of 50ml to a full volume of 1.5L. It has gastric juices (mixture of mucous, enzymes, hydrochloric acid and water) and pepsin which breaks down proteins. It secretes hormones to warn the pancreas and gallbladder of incoming chyme which gets released in small amounts to the small intestine.
What is the liver?
The liver is the largest gland in the body and produces bile (yellow-green fluid including salts secreted into small intestine) which breakdown fats, stores glucose as glycogen and metabolises waste nitrogen products.
What is the gallbladder?
The gallbladder is a organ which stores excess bile.
What is the pancreas?
The pancreas is a large gland that is connected to the small intestine duct and creates and secretes enzymes into the common bile duct. It creates and secretes Bicarbonate (neutralises stomach acid), Amylase (breaks down carbs), protease ( breaks down proteins), lipase ( break down of lipids) and nucleases (break down of rna, dna and cellular organelles).
What is the small intestine?
The small intestine is a long coiled tube that is the primary region for digestion of food. It receives enzymes from the pancreas and bile from the liver and gallbladder. Its made of duodenum, jejunum and ileum. Food spend 3-6 hours here and 90% of nutrients are absorbed. The inner lining of the small intestine is covered in a layer of villi and microvilli.
What is the caecum?
The caecum is a small pouch in humans that connect the small intestine and the colon and contains lymphoid tissue (fight bacteria and remove excess fluid).
What is the large intestine?
The large intestine is made of the colon and rectum. The colon absorbs water and the rectum egests faeces (undigested material) into the anus.
What is the endocrine system?
The endocrine system is made of a network of endocrine glands and acts as a chemical messenger. Endocrine glands are ductless and send signals via hormones through the bloodstream.
What are hormones?
Hormones are chemical messengers produced by the endocrine glands. They can be steroid (made from cholestrole and include cortisol and aldosterone and are hydrophobic so they diffuse easily) their receptors are cytosol and nuclease or proteins (like polypeptides or amino acids made od ADH and are hydrophillic so they cant diffuse easily) their receptors are the plasma membrane. Hormones regulate body processes such as metabolism, growth, glucose, water balance, and sexual development.
What is the pituitary gland?
The pituitary gland is located below the hypothalamus at the bottom of the brain and has two parts separated by a thin strip of tissue. The anterior pituitary (made of glandular tissue and make and secrete hormones that activate other endocrine glands) and the Posterior pituitary (made of neural tissue and stores and releases hormones from the hypothalamus).
What are the adrenal glands?
The adrenal glands are paired endocrine glands and are located just above the kidneys. Each gland is covered in a fibrous connective tissue capsule and have two parts. Both regions contain many capilarries amd blood vessels and the medulla has many nerve fibres and endings. The adrenal outer cortex is made of glandular tissue and synthesises and secretes corticoid hormones (steroids). The adrenal inner medulla is the central part of the adrenal glands and chromaffin cells which are highly modified nerve cells.
What is the thyroid gland?
The thyroid gland is shaped like a butterfly organ and is located in the neck around the trachea below the larynx. It has rich blood supply and is made of many follicles. Its lined with a layer of follicular cells which is filled with colloid made of thyroglobulin which synthesises t3 and t4 hormone. The thyroid gland is the only gland which can absorb iodine and uses it to make T3 and T4.
