01 - Homeostasis And Energy Flashcards
What is homeostasis?
The ability of the body to maintain relatively stable internal conditions even when the environment and/ or the the activity of the person is changing
Most organ systems are involved in homeostatic mechanisms, true or false?
True
What are the parameters that are controlled?
Temperature Concentration of nutrients in blood Heart rate Blood pressure Waste removal
What is the homeostatic state of the body controlled by?
The neural and endocrine systems
What do the homeostatic control systems involve?
>Receptors >Stimuli >Control centre >Effector >Reflex >Negative feedback >Positive feedback
What is negative feedback?
Response to a given stimulus which, causes an increase in output
In negative feedback what does the increase in output itself do?
It turns off (or down) the effect of the original stimulus
What is positive feedback?
Response causes an increase in the afferent signal so the response becomes stronger until the stimulus is removed
What is an example of positive feedback?
Uterine muscle contraction intensified by the release of the hormone oxytocin until the baby is born
What is the primary hormonal control made of?
Insulin and Glucagon
Islets of Langerhans contain the cells that secrete what?
Glucagon
Insulin
What are glucagon cells in islets in Langerhans cells?
Alpha cells, 20% of cells
What are insulin in Langerhans cells?
Beta cells, 70% of cells
How many amino acid peptide is insulin?
51
How many chains of what kind of bridge do insulin cells have?
2 chains of s-s bridges
What is insulin secretion stimulated by?
Rising blood concentration, amino and fatty acid levels and parasympathetic neural action
What do insulin cells do?
Lower blood glucose concentration and promotes protein synthesis and fat storage
How do insulin cells lower blood glucose?
By enhancing glucose uptake by cells, particularly muscle and fat cells
By inhibiting glyconeogenesis - conversion of amino acids or fats into glucose
How many amino acid peptide does glucagon have?
29
What type of cells are glucagon cells?
Alpha cells of pancreatic islet
What is glucagon’s secretion increase stimulated by?
Increased in response to low glucose concentration of the blood, also sympathetic neural activation, and increased amino acid concentration
What is decreased secretion of glucagon stimulated by?
High glucose concentration, insulin and somostatin
What are glucagon’s primary target?
Liver cells
How does glucagon raise blood glucose?
- Stimulates glycogenolysis (breakdown of glycogen to glucose)
- Stimulates gluconeogenolysis (synthesis of glucose from lactic acid and from non-carbohydrate molecules)
- Stimulates the release of glucose into blood stream
