Blood Glucose Homeostasis

Glucose

• Glucose comes from _______________________.

• Glucose is used in the process of _________________ respiration to make ______________.

• ATP is the cells energy currency!

Blood Glucose Homeostasis• Glucose is the transport carbohydrate

in animals.– Its ____________________________ in the

blood affects every cell in the body.– Its concentration is controlled within the

range of 0.8 to 1 g/dm3 of blood.– ____________________________: low levels of

blood sugar.– ______________________________: high levels

of blood sugar.– High or low levels can be very serious and

can lead to death.

Blood Glucose Homeostasis

• Blood glucose concentration is ___________________ by the pancreas and the _______________.

• The pancreas has glucose ___________________ cells which monitor the concentration of glucose in the blood.– It also has _____________________ cells

that secrete hormones.

Blood Glucose Homeostasis

• Hormones secreted are _________________ and ______________________.– Insulin stimulates the _________________

of glucose by cells for respiration.– In the ____________________ insulin

stimulates the conversion of glucose to _______________________ (this process is called glycogenesis).

– Insulin _____________________ blood glucose.

• _________________________ stimulates the breakdown of _________________ into _______________________ in the liver (this process is called glycogenelysis).– In some extreme cases it can also

stimulate the synthesis of glucose from pyruvate.

– Glucagon ________________________ blood glucose.

Blood Glucose Homeostasis

• After a meal, glucose is absorbed from the gut into the hepatic portal vein, increasing the blood glucose concentration.– This is ________________________ by the

pancreas, which secretes insulin in response.

– Insulin causes glucose to be taken up by the liver and is converted to glycogen.• This ___________________ blood glucose, which

causes the pancreas to _________________ secreting insulin.

Blood Glucose Homeostais

• If the glucose level falls off too _____________, the pancreas detects this and __________________ glucagon.– Glucagon causes the liver to

_________________ down some of its glycogen store to ___________________.

– This diffuses into the blood, causing an increase in blood glucose, which causes the pancreas to ___________________ producing glucagon.

Blood Glucose Homeostasis

• Because blood glucose levels are allowed to deviate from their set point by __________ before any corrective mechanism is activated, glucagon and insulin can never both be produced at the same time.

• Set point is __________ to ____________ mg/dL.

Organs involved in Blood Glucose Regulation

• _______________• _________________ – Stores glucose as

glycogen• __________________ – releases certain type

of hormones depending on if glucose is present or absent in the blood.– If glucose is high then insulin is released.– If glucose is low then glucagon is released.

• ___________________ – The control center• Blood vessels – transport blood and

glucose throughout the body.

Organs and Organ Systems

• Muscles – Muscular System• Liver – Digestive System• Brain and Neurons – Nervous System• Blood Vessels – Circulatory System• Pancreas – Endocrine System

Regulatory Response

Behavioral Responses

• _______________ and ____________________

• Exercise:– Muscles cells use glucose to make ATP

(energy currency)– When muscles are worked out longer the

more glucose is used and the lower your blood glucose level will be.

– Muscles _____________________ glucose when not active.

Diabetes Mellitus• ______________________ is a disease caused

by the failure of glucose homeostasis.• There are two forms of the disease.– ______________ ___ Diabetes (10%): Also known

as insulin dependent or early-onset diabetes.– There is a severe insulin deficiency due to an

autoimmune reaction that kills the cells, that secrete insulin.

– Appears to be an inherited condition, possibly triggered by a virus.

– In this condition, no insulin is produced.– Can be treated by injections with insulin.

Diabetes Mellitus

• ____________ _____ Diabetes (90%) Also known as non insulin-dependent or late – onset diabetes.– Insulin is produced, but the insulin receptors in the

target cells don’t work, leaving insulin with no effect.

– This is often a response to years of over-production of insulin, caused by a high-sugar diet.

– Can be treated by careful diet (balancing sugar intake with exercise) or by tablets that stimulate insulin production or increase the sensitivity of the liver cells to the hormone.

Blood Glucose Homeostasis• Until the discovery of insulin in ____________,

diabetes was an untreatable, fatal disease.• Symptoms of Diabetes:– High _____________ due to osmosis of water from

cells to the blood.– High urine production due to excess water in blood.– Poor _______________ due to osmotic loss of water

from the eye lens.– ______________________ due to the loss of glucose in

urine and poor uptake of glucose by the liver and muscle cells.

– Ketone breath caused by the body breaking down lipids to supply energy.

– Muscle wasting due to gluconeogenesis caused by increased glucagons.