Unit 2 Homeostasis

Question 1

label a nephron (distal convoluted tubules, loop of Henle, proximal convoluted
tubules and the collecting duct).

Answer 1

Check onenote

Question 2

Define and describe negative feedback

Answer 2

Negative feedback systems maintain homeostasis by producing a response that is the opposite of the original change.

Negative feedback decrease the original stimulus

Question 3

define and describe homeostasis

Answer 3

Homeostasis refers to the body’s maintenance of internal environments within tolerance limits despite stimuli from the external environment

Question 4

What is osmotic pressure

Answer 4

Osmotic pressure refers to the tendency of a solution to take in the pure solvent
Simply put, Osmotic pressure is determined by the concentration of substances dissolved in the water of the blood plasma.

Question 5

distinguish between excretion and elimination

Answer 5

Excretion - removal of products of metabolism
Eliminations - removal of undigested food

Question 6

define and describe a positive feedback

Answer 6

Positive feedback has no role in homeostasis. When it occurs, the response to a stimulus reinforces and intensifies the stimulus

Question 7

how does a positive feedback reinforce a stimulus

Answer 7

The intensified stimulus results in an even greater response, it does this through the nervous and endocrine system

Question 8

Give examples of positive feedback

Answer 8

Childbirth
Blood clotting

Question 9

give examples of negative feedback

Answer 9

Thermoregulation
Blood glucose regulation
Gas concentration regulation
Bodily fluids regulation

Question 10

recall the basic process of aerobic respiration

Answer 10

A chemical process in which oxygen is used to make energy from carbohydrates.
Formula;
C6H12O6 + 6O2 → 6CO2 + 6H2O

Question 11

How is carbon dioxide carried in the blood plasma

Answer 11

Carbon dioxide is carried in the blood plasma as hydrogen ions

Question 12

What do the following terms mean;
Neo
Genesis
Lysis
Lipo

Answer 12

– Neo = New
– Genesis = Creation
– Lysis = Breakdown of cell
– Lipo = fat

Question 13

Define thermoregulation

Answer 13

Thermoregulation refers to the regulation of body temperature; the balance of heat gain and heat loss in order to maintain a constant internal body temperature independent of the environmental temperature

Question 14

Describe the components of the stimulus-response feedback model

Answer 14

○ The STIMULUS is the change in the environment that causes the system to operate
○ The RECEPTOR detects the change
○ The MODULATOR is a control centre responsible for processing information received from the receptor and for sending information to the effector
○ The EFFECTOR carries our a response counteracting or enhancing the effect of the stimulus
○ FEEDBACK is achieved because the original stimulus has changed by the response

Question 15

How does the body react to an INCREASE in body temp

Answer 15

Stimulus - Increase in body temperature
Receptor - peripheral thermoreceptors are stimulated sending info to the hypothalamus
Modulator - The hypothalamus responds through the effector
Effector -
*Vasodilation of skin areterioles occur
* Sweating occurs
* Behavioural response occurs
* In the long term, can be a decrease in metabolic rate
Response -
* Vasodilation causes an increase in blood flow through the skin, with the surface temperature rising causing heat loss through convection
*Sweat evaporates having a cooling effect
*Decrease in metabolic rate causes less heat to be produced in the body
Feedback - body temperature decreases

Question 16

how does the body react to a DECREASE in body temp

Answer 16

Stimulus
-decrease in body temp
Receptor
- peripheral thermoreceptors are stimulated sending info to the hypothalamus
Modulator
- Hypothalamus activates the effectors
Effector
* Skeletal muscles cause shivering
* Vasoconstriction of skin blood vessels
* Adrenal medulla secretes adrenaline and noradrenaline increases cellular metabolism
* Pituitary gland releases TSH which causes the thyroid to release thyroxine into the blood
* Behavioural change
Response
* Shivering increases heat production
* Vasoconstriction causes a reduction in heat loss
* Increased metabolism causes the body to produce more heat
* Thyroxine increases metabolic rate, which increases the heat produced
Feedback - body temperature increases

Question 17

how does the body react to an INCREASE in blood glucose

Answer 17

Stimulus
- Increase in blood glucose
Receptor
- chemoreceptor detects increase in blood sugar sending information to the hypothalamus
Modulator
- Hypothalamus activates the liver, adrenal glands and pancreas
Effector
* Pancreas secretes insulin and glucagon through alpha and beta cells. Insulin causes a decrease in blood glucose levels
* Liver converts glucose to glycogen for storage through the process of glycogenesis
Response
* Insulin causes a decrease in blood glucose levels
* Liver causes the glucose to be used for storage
Feedback
- Decrease in blood glucose

Question 18

how does the body react to an DECREASE in blood glucose

Answer 18

Stimulus
- Decrease in blood glucose
Receptor
- chemoreceptors detect decrease in blood sugar sending information to the hypothalamus
Modulator
- Hypothalamus activates the liver, adrenal glands and pancreas
Effector
* Pancreas secretes glucagon through alpha cells. Glucagon causes an increase in blood glucose levels
* Liver converts glycogen to glucose for use through the process of glycogenolysis
Response
* Glucagon causes a decrease in blood glucose levels
* Liver causes the glucose to release into the blood
Feedback
- Decrease in blood glucose

Question 19

how does the body react to an INCREASE in bodily fluids

Answer 19

Stimulus
- increase in bodily fluids
Receptor
- Osmoreceptors in the thirst centre of the hypothalamus detect an increase in plasma volume and decrease in osmotic concentration of extracellular fluid
Modulator
- The thirst centre of the hypothalamus is stimulated making the person feel overly hydrated
Effector
- The kidneys begin with excretion being excreted as urine
- Adrenal glands release aldosterone to maintain sodium levels within the body
Response
- Kidneys excrete at a faster rate and release excrete large volumes of water
- Aldosterone maintains the sodium levels in the body
Feedback
- Decrease in bodily fluids

Question 20

how does the body react to an DECREASE in bodily fluids

Answer 20

Stimulus
- Decrease in bodily fluids
Receptor
- osmoreceptors in thirst centre of hypothalamus detect the increased osmotic pressure of blood
Modulator
- the hypothalamus stimulates the posterior lobe of the pituitary gland and the thirst centre is stimulated
Effector
- Posterior lobe of pituitary gland releases ADH which is carried to nephron tubules
- Thirst centre makes the person feel thirsty to trigger a behavioural response
Response
- ADH increases the permeability to water of the distal convoluted tubules and the collect ducts - meaning more water is reabsorbed into the blood plasma
- Water is consumed replenishing thirst
Feedback
- Increase in bodily fluids

Question 21

how does the body react to an INCREASE in gas concentrations (comeback to this card)

Answer 21

Stimulus
- Increase in CO2 concentration
Receptor
- Central chemoreceptors in medulla oblongata
Modulator
- Respiratory centre in the medulla oblongata sends nerve impulses to diaphragm and intercostal muscles
Effector
- Diaphragm and intercostal muscles have an increased rate and depth of breathing
Response
- Decrease in Co2
Feedback
- Decrease in breathing rate

Question 22

Distinguish between physiological and behavioural activities

Answer 22

Physiological activites - Nervous or Endocrine mechanisms - body does it subconsciously
Behavioural activities - conscious decisions to maintain homeostasis

Question 23

Name the four main components of homeostasis

Answer 23

Thermoregulation
Blood glucose
Gas concentrations
Bodily Fluids

Question 24

what are disruptions to homeostasis

Answer 24

Disruptions to homeostasis are;

Hormonal - Insulin & Thyroxine
Behavioural - Drugs, Exercise, Eating Habits
Disease - Emphysema, Fever, Hypertension

Question 25

What are important aspects of the internal environment

Answer 25

• Core body temperature
• pH and concentrations of dissolved substances in the body fluids
• Concentration of glucose in the blood
• Concentration of oxygen and carbon dioxide in the blood and other body fluids
• Blood pressure
• Concentration of metabolic wastes

Question 26

define and describe feedback systems

Answer 26

A FEEDBACK SYSTEM is a circular situation in which the body responds to a change, or stimulus, with the response altering the original stimulus and thus providing feedback.

Question 27

define glycogenolysis

Answer 27

the process of converting glycogen back to glucose

Question 28

define gluconeogenesis

Answer 28

the process of producing glucose molecules from lipids and amino acids

Question 29

define glycogenesis

Answer 29

the process whereby glucose molecules are chemically combined in long chains to form glycogen molecules

Question 30

define lipogenesis

Answer 30

the production of lipids

Question 31

define lipolysis

Answer 31

the breakdown of lipids in the body

Question 32

what are the normal levels of the main components of homeostasis

Answer 32

Body Temp - 36.8C
Blood Glucose concentration - 4-6 millimoles per litre
Bodily fluids - 45-60%

Question 33

What do alpha and beta cells secrete

Answer 33

Alpha cells - secrete glucagon
Beta cells - secrete insulin

Question 34

how does insulin cause a decrease in blood glucose levels

Answer 34

○ Accelerating the transport of glucose from the blood into body cells, especially those of the skeletal muscle
○ Accelerating the conversion of glucose into glycogen in the liver and skeletal muscles
○ Stimulating the conversion of glucose into protein
○ Stimulating the conversion of glucose into fat in adipose tissues, or fat storage tissue, a process known as lipogenesis

Question 35

how does glucagon cause an increase in blood glucose levels

Answer 35

○ Stimulating glycogenesis
○ Stimulating gluconeogenesis - this involves the breakdown of lipids through lipolysis
○ Having a mild stimulating effect on protein breakdown

Question 36

distinguish between aortic body and carotid body

Answer 36

Aortic body - the group of cells within the walls of the aortic arch that are sensitive to changes in the concentrations of oxygen and carbon dioxide in the blood and its pH
Carotid body - the group of cells within the walls of the carotid arteries that are sensitive to changes in the concentration of oxygen and carbon dioxide in the blood and its pH

Question 37

distinguish between vasodilation and vasoconstriction

Answer 37

Vasodilation - increase in heat loss - widening of blood vessels

Vasoconstriction - reduction in heat loss - shortening of blood vessels

Question 38

define and describe the four methods of heat transfer

Answer 38

Conduction: The transfer of heat through a material or between materials in direct contact with each other, due to a temperature difference.

Convection: The transfer of heat through a fluid (liquid or gas) by the movement of the fluid itself, due to a temperature difference.

Radiation: The transfer of heat through electromagnetic waves, which can travel through a vacuum and do not require a medium.

Evaporation: The transfer of heat through the process of changing a liquid to a gas, which requires energy and removes heat from the surroundings.