Chapter 09 - Homeostasis and Hormonal Control Flashcards
What is homeostasis?
Homeostasis is the maintenance of a constant internal environment (allows organisms to be independent from changes in external environment)
What does the internal environment of the human body include?
The internal environment includes the blood and tissue fluids that surround the cells in the body
What are the 3 things to be kept constant?
1) Water potential of blood and tissue fluid
2) Body temperature
3) Blood glucose concentration
Why is body temperature regulation important?
Body temperature must be kept constant because enzymes can only work within a certain range of temperatures
What can happen if body temperature changes?
Changes in body temperature can result in enzyme inactivation or even denaturation
What happens when there are drastic changes in the water potential?
- If wp is higher than normal, cells swell and burst
- If wp is lower than normal, cells crenate
What role do the islets of Langerhans play in blood glucose regulation?
The islets of Langerhans secrete the hormones insulin and glucagon to regulate blood glucose concentration
Why would a drastic change in BGC be dangerous?
Insulin and glucagon are important hormones in the regulation of BGC. Body cells need glucose for cellular respiration. Cellular respiration provides cells with energy to preform vital activities
In homeostatic control, your body brings about an ____ effect of the changes detected
In homeostatic control, your body brings about an opposite effect of the changes detected
What is the negative feedback process?
When a disturbance occurs in the body, it sets in motion a sequence of events to restore the body to its original state
What is the negative feedback process in homeostasis?
The negative feedback process involves the receptor detecting a stimulus, sending signals to a control center, and initiating a corrective mechanism to oppose the change and restore the factor to normal
What is a stimulus?
A change in the environment
What is a receptor?
Detects the stimulus and send signals to control center
What is the corrective mechanism?
Brings about the reverse effect of stiulus
What happens when the water potential of blood increases above normal?
Receptor: Hypothalamus is stimulated
Corrective mechanism:
- Less ADH released by the pituitary gland into blood stream
- Less ADH transported to kidney
- Cells in walls of collecting ducts become less permeable to water
- Less water reabsorbed into blood stream
- More water excreted
- Urine is more diluted
- More urine produced
Water potential of blood decreases to the normal level
What happens when the water potential of blood decreases below normal?
Receptor: Hypothalamus is stimulated
Corrective mechanism:
- More ADH released by the pituitary gland into blood stream
- More ADH transported to kidney
- Cells in walls of collecting ducts become more permeable to water
- More water reabsorbed into blood stream
- Less water excreted
- Urine is more concentrated
- Less urine produced
Water potential of blood increases to the normal level
What is a hormone?
A hormone is a chemical substance produced in minute quantities by an endocrine gland, transported in the bloodstream to target organs
What distinguishes endocrine glands from exocrine glands?
Endocrine glands are ductless and secrete hormones directly into the bloodstream, while exocrine glands have ducts to carry their secretions
Some glands can be both ____ and ____
Some glands can be both endocrine and exocrine. For example the pancreas produces and secreted pancreatic juice through a duct as well as hormones insulin and glucagon into the blood directly
What does the pituitary gland release and what is the function of that hormone?
ADH. Affects permeability of walls in the collecting ducct to regulate the amount of water being reabsorbed from the glomeullar filtrate in the nephron
What does the pancreas (Islets of Langerhans) release and what is the function of that hormone?
Insulin and glucagon.
- Insulin promotes conversion of glucose to glycogen
- Glucagon promotes the conversion of glycogen to glucose
What does the testes release and what is the function of that hormone?
Testoterone.
- Stimulates sperm producation
- Stimulates development of male charcteristics
What does the ovaries release and what is the function of that hormone?
Oestrogen and progesterone.
- Oestrogen stimulates the repair and thickening of the uterus lining
- Progesterone maintains the thickness of the uterine lining
- Stimulates the egg development
- Stimulates the development of female characteristics
What happens when blood glucose concentration rises above normal?
The islets of Langerhans secrete more insulin, increasing glucose uptake by cells and converting excess glucose to glycogen
What happens when blood glucose concentration decreases below normal?
The islets of Langerhans secrete more glucagon, which stimulates the conversion of glycogen back to glucose
What happens when there is an abnormal blood glucose concentration decrease?
What is the effect of glucagon?
Glucagon increases blood glucose concentration by stimulating the conversion of glycogen into glucose
What is the effect of insulin?
Insulin decreases blood glucose concentration by making cell membranes more permeable to glucose and stimulating glycogen storage
What is diabetes mellitus?
Diabetes mellitus is a disease in which the body is unable to control its blood glucose concentration, leading to high levels of glucose in the blood
What are the 2 types of diabetes mellitus?
The two main types of diabetes are type 1 (juvenile) and type 2 (late onset)
True or False: Type 1 diabetes is often inherited and occurs early in life
True
List some common signs and symptoms of diabetes
- Persistently high blood glucose levels
- Presence of glucose in urine
- Slow or difficult healing of wounds
- Frequent urination
- Weight loss
- Increased thirst
What lifestyle changes can reduce the risk of type 2 diabetes?
- Eating healthily (low calories, high fiber)
- Engaging in physical activity
- Maintaining a healthy body weight
- Avoiding prolonged inactivity
