Homeostasis of blood sugar breathing and blood pressure

Homeostasis of blood sugar, breathing and blood pressure Chapter 9 Stage 3 Human Biological Science

Keywords � Glucose � Glycogen Liver � Glycogenesis � Glycogenolysis � Gluconeogenesis Pancreas � Islets of Langerhans � Insulin � Glucagon Pituitary gland � ACTH Adrenal glands � Cortisol � Adrenaline � Noradrenaline

Role of the liver �We need glucose (from the food we eat) for cellular energy �The liver plays a major role in the control of blood glucose levels �The body cannot store glucose, so the liver converts it to glycogen for storage �When the body needs glucose, glycogen is converted back to glucose for release into the blood

Glycogenesis �The process of converting glucose to glycogen is called glycogenesis �This process is stimulated by the hormone insulin �Glycogen itself cannot be used by cells so it must be converted back to glucose for use

Glycogenolysis �Glycogenolysis is the process which converts glycogen back to glucose for use �This process occurs mostly between meals �This process is stimulated by the hormone glucagon

Role of the pancreas �The pancreas contains hormone secreting cells called the islets of Langerhans �There are 2 types of: alpha cells and beta cells �Alpha cells secrete glucagon �Beta cells secrete insulin

Role of the pancreas Insulin from the beta cells causes a decrease in BGL by accelerating: 1. the transport of glucose from the blood into the cells, especially skeletal muscle cells 2. the conversion of glucose into glycogen Insulin can also �Stimulate the conversion of glucose into fat in adipose tissue (fat storage tissue) �Cause a increase in protein synthesis in some cells

Role of the pancreas Glucagon from the alpha cells causes an increase in BGL by stimulating �the process of glycogenolysis in the liver �the liver to produce sugar molecules from fats and amino acids, a process called gluconeogenesis

Glycogenesis Reduced level of blood glucose High blood glucose Beta cells (pancreas) Stimulus Receptor Beta cells Secrete insulin Feedback Response · Glycogenesis · Increased glucose uptake · Lipogenesis Effector · Liver · Somatic cells

Glycogenolysis Increased level of blood glucose Low blood glucose Stimulus Alpha cells (pancreas) Receptor Alpha cells Secrete glucagon Feedback Response · Glycogenolysis Effector · Liver

Role of the adrenal glands The pituitary gland, adrenal cortex and adrenal medulla also have a role in regulating BGL �Pituitary gland secretes adrenocorticotrophic hormone (ACTH) �ACTH acts on the adrenal glands. They secrete glucocorticoids (cortisol) which are involved in gluconeogenesis

The adrenal medulla �The adrenal medulla synthesis adrenaline and noradrenaline which act to stimulate the breakdown of glycogen in the liver and the release of glucose into the blood

Links �http: //bcs. whfreeman. com/thelifewire/content/chp 50 /5002 s. swf �http: //www. brown. edu/Courses/BI 0020_Miller/week/ 10/web-2/4 -2 -2007_10 -2110/Chapter_41/Present/Animations/41_A 02 s. h tml �http: //www. mhhe. com/biosci/genbio/tlw 3/e. Bridge/C hp 27/animations/ch 27/1_glucose_regulation. swf �http: //outreach. mcb. harvard. edu/animations/homeos tasis 10. swf