Unit 3: SAC 4: Detecting And Responding. Flashcards
In order for homeostasis to occur what factors from the internal environment of a cell may need be adjusted?
Temp
Blood glucose concentration
Oxygen and Carbon Dioxide levels
Water balance
In order for homeostasis to occur what factors from the external environment of a cell may need be adjusted?
Temp Blood glucose concentration Oxygen and Carbon Dioxide levels. Water balance PH level.
What is the endocrine system?
The endocrine or hormonal system produces hormones that are screwed directly into the bloodstream and transported throughout the body where they regulate cell activities.
What is the nervous system?
The nervous system receives and transmits information about both the external and internal environment. The nervous system transmits electrical impulses to body cells that respond in various ways.
What happens when there is too much glucose in the blood?
Beta cells produce more insulin allowing more glucose to be absorbed by cells leading to a decrease in blood glucose levels. Levels will continue to decrease until they become lower than 3.9, when at this point negative feedback occurs and alpha cells then secrete glucagon which allows glycogen to be converted to glucose and enter the bloodstream. Levels then increase until they become too high when beta cells then take over the reoccurring process.
What happens when there is too little glucose in the blood?
When there is too much glucose in the blood, alpha cells secrete glucagon which allows glycogen to breakdown into glucose that then enters the bloodstream, increasing blood glucose levels. Levels will continue to increase until they go above 5.6, when at this point beta cells secrete insulin that allowing more glucose to be absorbed by cells leading to a decrease in blood glucose levels. Levels then decrease until they drop below 3.9 when alpha cells take over the reoccurring process.
What is negative feedback?
Negative feedback is a process in which an undesirable change in a variable of an organism’s environment (a stimulus) is detected. Leading to a response within the body to reverse the direction of the change.
Name the three types of hormones? Which are lipid soluble and which are water soluble.
Amino Acid hormones and peptide hormones are water soluble, not lipid soluble and as such can’t pass through the cell membrane, they therefore need protein receptors to start the signal transduction pathway/cascade, secondary Steroid hormones are lipid soluble and are able to pass through the cell membrane and bind to protein receptors on the nucleus’ membrane, starting the cell transduction pathway/cascade that results in the production of proteins from DNA.
What is homeostasis?
Cells in multicellular organisms need to maintain a relatively stable internal environment, so that normal cellular functions can be performed. This allows cells to perform at optimum efficiency. This is called homeostasis.
Describe the stimulus response model.
The stimulus is received by a receptor which then sends hormones or neurones to the hypothalamus where the pituitary gland then sends hormones or nerves to an effector that triggers a response, that response is negative feedback.
