Lec 18 - Homeostasis and Regulation of Glucose

define homeostasis

the maintenance of internal balance

define set point

a value maintained for a certain variable

define regulator

uses internal mechanisms to control internal change in animal during external fluctuation

define conformer

animal that allows its internal condition to change in accordance with external changes in particular variable

how are things in the body regulated?

enzyme regulation, transcriptional regulation, hormonal regulation/signaling, neural regulation/signaling

What is enzyme regulation?

negative feedback inhibition: when end products go back and inhibit prior steps in a pathway (PFK)

What is transcriptional regulation?

transcription factors (proteins) up or down regulate the expression of genes.

What is hormonal regulation?

body using hormones (chemical messengers) that travel through the blood telling organs what to do (Endocrine system)

What is neural regulation?

body using nerve cells (neurons) to send electrical signals to organs/muscles to control their activity (nervous system)

Human body temp set-point

98.6F and 37C

Human blood pH set-point

7.35-7.45

Human blood glucose set-point

70-110 mg(glucose)/100ml(blood)

define control system

generates output that triggers a response

define stimulus

a fluctuation in a variable that triggers a response (temp increasing)

Define effector

the thing that tells something to change

define response

physiological activity that helps return variable to set point (temp decreasing)

define sensor

receptor that detects stimulus

define negative feedback

"damps" stimulus and tries to bring it back to setpoint (figure 8 diagram)

define positive feedback

amplifies stimulus, not to get to setpoint, but to drive process to completion (childbirth)

define circadian rhythm

body's natural 24 hr cycle that regulates many physiological processes

define acclimatization

animals physiological adjustment to changes in its external environment.

where is insulin made?

made by pancreatic beta cells

what does insulin do (stimulate)?

helps glucose get into cells lowering blood glucose levels, stimulates liver cells to convert glucose into glycogen

what does insulin do (promote)?

promotes fatty acid synthesis from glucose in the liver when it has enough glycogen, promotes glycerol production in fat cells.

What is GLUT4?

a glucose transporter protein that moves to cell membrane in response to insulin to let glucose in (facilitated diffusion?

When insulin doesn't trigger it, where does GLUT4 live?

in vesicles floating inside of cell

What is insulin receptor signaling?

when insulin binds to receptor in cells surface, triggering a chain of signals inside cell telling it to let glucose in through GLUT4 and to use it

What happens to blood glucose levels after insulin is secreted by the pancreas?

blood glucose level decreases because insulin allows glucose to be taken up by cells.

what is glycerol?

A 3-carbon molecule that forms the backbone of fats (triglycerides)

what is glycogen?

the stored form of glucose in liver in muscles (Short term storage)

how do plants store glucose?

as starch

how do animals store glucose? where in the body?

as glycogen in liver and muscles

Where is Glucagon made?

in pancreatic alpha cells

What is glucagon?

a hormone that promotes the breakdown of glycogen in the liver and the release of glucose in the blood (opposite of insulin)

What is diabetes?

disease where body cannot regulate blood glucose properly

Type 1 Diabetes

pancreatic beta cells cannot make enough insulin (genetic)

Type 2 diabetes

person develops insulin resistance by having too much glucose and insulin around all the time

What happens when glucose gets too high?

glucose binds to things it shouldn't, damage blood vessels, measured by hemoglobin

what happens when blood glucose gets too low?

weakness, dizziness, seizures

provide a general explanation as to how the endocrine system allows different parts of the body to communicate with one another

uses hormones in the blood to send signals between organs and coordinate body functions