Biopsychology Post-Midterm
SEE FIGURE 12.12 IN TEXTBOOK FOR METABOLIC PATHWAYS
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SEE POWERPOINT FOR "INSULIN/GLUCAGON FEEDBACK SYSTEM"
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What does saliva do?
Begins breaking down food with enzymes
Who discovered won Nobel Prize in 1920s for discovery of insulin?
Best and Banting
Stomach conveys message about its stretching to the brain via the ____.
CN #X Vagus Nerve
What happens with glucose?
Cells in periphery are unable to use glucose bc their uptake is dependent on insulin. Glucose is eliminated in urine. Hunger signals remain high.
How do chronically high levels of glucose affect the retina of the eye?
Condition called diabetic retinopathy. Retina can detach from the back of the eye and evaporate.
What has been called the "hunger hormone"?
Ghrelin
Untreated diabetes cycle
Hunger -> Eating -> blood glucose increases, but insulin levels remain low -> glucose does not enter cells; leaves in urine and feces instead. Hunger remains high. -> blood-glucose levels remain high, but cells are starving
What is important about the duodenum?
It is where nutrients from food are absorbed into the bloodstream.
Define satiety
NOT just the absence of hunger
What happened prior to discovery of insulin?
People with diabetes died
What is the purpose of the pancreas?
Produces insulin. Releases when a person starts eating glucose. Insulin allows body organs to take in glucose and use it for energy.
What is one purpose of the liver?
Removes excess glucose that is not immediately needed for energy. Stores converts and stores stored glucose as glycogen. When glucose runs low, the liver converts it back to glucose.
CCK limits meal size in two ways. Name them.
Slows down rate of stomach emptying; stimulates Vagus nerve, which sends signal to hypothalamus about presence of food
When blood glucose levels decrease (about two hours after eating), what happens?
The hormone glucagon causes the liver to convert glycogen back to glucose.
When blood-glucose levels remain high for a long time, what happens to the kidneys?
They work very hard; people often have to go for dialysis.
How many valves in stomach?
Two
Which cranial nerve deals with movement of stomach muscles?
Vagus (X)
What is Ghrelin?
a peptide secreted by the stomach that promotes eating
As time passes after a meal, 3 things happen. List them
blood glucose drops; insulin levels drop; hunger signals increase
What is the only organ that doesn't need insulin to use glucose for energy?
brain
Presence of food in the duodenum, esp fats or amino acids, results in the secretion of _____.
cholecystokinin (CCK)
Upper stomach valve Fx?
controls flow of food into stomach
Lower stomach valve Fx?
controls flow of food out of stomach
Stomach contains receptors. What do they do?
detect stomach distention; keep track of nutrients present in stomach
Where does food go after stomach?
duodenum, upper portion of small intestine
Define redundancy
eating is controlled by a number of signals (mechanical, chemical) that originate in various peripheral organs (stomach, small intestine, liver, pancreas) and brain areas
What constitutes the upper GI tract?
eyes, nose, tongue, throat
What does the opposite of Ghrelin?
food ingestion
Symptoms of diabetes in Best and Banting's dogs?
hyperdipsia (excessive thirst), hyperglycemia (excessive glucose), hyperuria (excessive urination), hyperphagia (excessive eating)
What is the primary deficit in Type II Diabetes?
insufficient production of insulin by pancreas or the body cannot use the insulin for a variety of reasons
Two hormones secreated by the pancreas
insulin and glucagon
What three things happens when blood glucose is high?
insulin increases, allowing cells to take glucose from blood; liver cells convert glucose to glycogen; fat cells convert glucose into fat (triglycerides) for long-term storage
GI Tract
mouth -> salivary glands -> esophagus -> liver -> stomach -> duodenum -> gallbladder -> pancreas -> small intestine -> large intestine -> rectum
What controls release of Ghrelin?
receptors in the duodenum; when a meal begins and food begins to enter the duodenum, Ghrelin release stops
The acts of _____ and _____ provides info that is used by the body to interpret the amount and type of food that is ingested. Learning plays an important role.
tasting; swallowing
Define homeostasis
tendency to maintain a variable within a fixed range
Which CN deals with chewing?
trigeminal (V)
