Unit 8 Homeostasis

Question 1

What is homeostasis?

Answer 1

• A state of balance among all the body systems needed for the body to survive and function correctly.

Question 2

What are the 3 conditions to maintain homeostasis within the body?

Answer 2

• maintaining proper concentrations of gases, nutrients, water and salts
• maintaining an optimum temperature temperature of 37°C for chemical reaction rate and proper protein shapes
• maintaining an optimum pressure for the proper concentrations of various substances and the rates they move through the body

Question 3

What is an external stressor and internal stressor examples?

Answer 3

• lack of environmental oxygen, extreme environmental temperatures
• rapid changes in blood pressure, changes in nutrient levels

Question 4

What are the 5 basic components of a feedback system?

Answer 4

Stimulus
sensory
control centre
effector
response

Question 5

What is a negative feedback system?

Answer 5

A mechanism that reverses a deviation from the setpoint

Question 6

Describe what happens when body temperature is increased?

Answer 6

(receptor) Sensors detect the increase in the body temperature and send this to the hypothalamus of the brain

(control centre) The hypothalamus stimulates the thermal regulatory centre with these three consequences

(Effector) - blood vessels in the skin dilate

• sweat glands are activated
• depth of respiration increases

Question 7

What happens when decreased body temperature?

Answer 7

(receptor) Sensors detect decrease in body temperature and send this to hypothalamus

(Control centre) Hypothalamus sends message to thermoregulatory centre

(effector)

• blood vessels in the skin constrict
• skeleton muscles receives random signals a contract
• the thyroid gland is triggered to release thyroid hormone,
• the adrenal glands are signal to release epinephrine

Question 8

What happens when there is excess glucose in the body?

Answer 8

(receptor)Beta cells detect excess glucose in the blood stream

(Control Centre)Beta cells Releases hormone insulin

(Effector) - insulin signals skeletal muscle fibers, adipocytes, and liver cells to take up excess glucose

(Response) Glucose levels return to normal

Question 9

What is a positive feedback system?

Answer 9

Intensifies a change in the bodies physiological condition.

Example: child birth, blood clotting, urination

Question 10

What is the childbirth positive feedback loop?

Answer 10

(stimulus) - first contractions of humour push the baby towards the cervix
(sensor) - the cervix contain stretch sensitive nerve cells that monitor the degree of stretching and send messages to the brain

(Control centre) - the pituitary gland releases the hormone oxytocin in the back into the bloodstream

(effectors) - oxytocin causes stronger contractions, pushing the baby further down the birth canal
(response) - this causes even greater stretching of the cervix

Question 11

Describe blood clotting using the positive feedback loop

Answer 11

• Following a penetrating wound, the most immediate threat is excessive blood loss
• the body responds by releasing substances in the injured blood vessel wall that begin the process of blood clotting
• as each type of clotting occurs, it’s simulator release of more clotting substances, accelerating the processes of cutting and sealing off the damaged area