Homeostasis and Thermoregulation Flashcards Preview

Human Biology Unit 3 + 4 > Homeostasis and Thermoregulation > Flashcards

Flashcards in Homeostasis and Thermoregulation Deck (52)
Loading flashcards...
1

Homeostasis

Maintenance of internal environment

2

Feedback system consists of a

Stimulus
Receptor
Modulator
Effector
Feedback

3

Negative Feedback Loops

Where the response causes the stimulus to change in a direction opposite to that of the original stimulus

4

Positive Feedback

The response to stimulus reinforces and intensifies the stimulus

5

Thermoregulation

Human body Temperature

6

Heat Gain

1. Internal
- Metabolic rate

2. External
- Radiation or conduction

7

Heat Loss

1. Internal
- Evaporation of water from skin and lungs
- Warm air breathed out
- Warm urine and faeces

2. External
- Radiation, conduction and convection

8

Conduction

Transfer of heat via direct contact with another object

9

Convection

Transfer to heat to air around the body

10

Radiation

Transfer to heat without contact

11

Evaporation

Transfer of heat through evaporation of liquid to gas

12

Temperature Tolerance

1. Heat stroke (body temp rises by regulatory mechanisms not working)

2. Heat Exhaustion (result of extreme sweating and vasodilation)

3. Hypothermia (cored body temp falls below 33 degrees)

13

Temperature Receptors

1. Peripheral thermoreceptors in skin and mucous membranes

2. Central Thermoreceptors in hypothalamus

14

Thermoregulation Short term Keeping Cool

Stimulus
Increase in body temp

Receptor
Thermoreceptors (central and peripheral)

Modulator
Hypothalamus

Effector
Sweat Glands
Blood Vessels
Cerebrum

Response
Increase sweating
Vasodilation
Behavioural

15

Thermoregulation Long Term Keeping Cool

Stimulus
Increase body temp

Receptor
Thermoreceptors

Modulator
Hypothalamus

Effector
Thyroid

Response
Decrease metabolic rate, which decreases heat production

16

Thermoregulation Long Term Keeping Warm

Stimulus
Decrease in body temperature

Receptor
Thermoreceptors (central only)

Modulator
Hypothalamus

Effector
Thyroid

Response
Increase Metabolic rate which increases heat production

17

Thermoregulation Short Term Keeping Warm

Stimulus
Decrease in body temperature

Receptor
Thermoreceptors (central and peripheral)

Modulator
Hypothalamus

Effector
Skeletal muscle
Blood vessels of skin
Cerebrum
Adrenal Medulla

Response
Shivering
Vasoconstriction of BV
Behavioural
Adrenaline, Noradrenaline

18

Osmoregulation in blood

1. Water is lost from the blood resulting in blood having a higher osmotic pressure

2. High osmotic pressure is detected by osmoreceptors in the hypothalamus

3. Water then moves from the intracellular fluid into the plasma via osmosis

4. Resulting in lowering the concentration of water in the intracellular fluid which then causes water to leave the cells resulting in the cells to shrivel and shrink

19

Antidiuretic Hormone

ADH is produced by the hypothalamus and released by the posterior lobe of the pituitary

ADH controls the permeability of the walls of the distal convoluted tubule and the collecting duct

ADH concentration is high this results in the tubules being more permeable to water

This results in water enabled to be reabsorbed

Water leaving the tubule decreases volume of filtrate and increases the concentration of contents

20

Aldosterone

The Adrenal cortex also secretes aldosterone to increase amount of sodium reabsorbed into blood and increase the amount of potassium excreted into urine

Water is reabsorbed along with sodium so aldosterone can also regulated water content

ADH and Aldosterone work together to regulate water

21

Dehydrated Feedback loop

Stimulus
Increase in Osmotic pressure

Receptor
Osmoreceptors

Modulator
Posterior pituitary

Effector
DCT and CT of Nephron

Response
Increase permeability, which increases reabsorption of water into the blood

22

Thirst Feedback Loop

Stimulus
Increase osmotic pressure

Receptor
Osmoreceptors in the thirst centre

Modulator
Cerebrum

Effector
Alimentary canal

Response
Increase absorption of water into the blood

23

Dehydration

Symptoms:
Severe thirst
Low Blood pressure
Dizziness
Headache

24

Water Intoxication

Symptoms:
Lightheadedness
Headache
Vomiting
Might Collapse

25

How is breathing controlled?

Our diaphragm and intercostal muscles receive stimulation from nerves to contract

26

Control of Breathing

Breathing is controlled by the respiratory centre in the medulla oblongata

27

What effects breathing rate

Oxygen, Carbon Dioxide and Hydrogen Ions

Carbon Dioxide concentrations affect hydrogen ion concentrations due to when co2 dissolves in water it forms carbonic acid which breaks down to form hydrogen ions

28

Chemoreceptors

Peripherally --> Aortic and Carotid bodies

Centrally --> medulla oblongata

29

Increase CO2, H+ and decrease in pH feedback loop

Stimulus
Increase CO2
Increase H+ ions
Decrease in pH

Receptor
Chemoreceptors in aortic and carotid bodies

Modulator
Respiratory centre in medulla olbongata

Via Phrenic and Intercostal nerves

Effector
Diaphragm and intercostal muscles

Response
Increase rate and depth of breathing

= Decrease CO2 Concentration

30

Decrease CO2, H+ and increase pH

Stimulus
Decrease CO2
Decrease H+ ions
Increase pH

Receptor
Chemoreceptors in aortic and carotid bodies

Modulator
Respiratory centre in medulla oblongata

VIA PHRENIC AND INTERCOSTAL NERVES

Effector
Diaphragm and intercostal muscles

Response
Decrease rate and depth of breathing

= Increase CO2 concentration

31

Holding Breath

CO2 will build up

This stimulate the inspiratory centre to stimulate the inspiratory muscles to take a breath

32

Hyperventiliation

It provides more O2 than needed and removes more CO2

Low CO2 = no urge to breathe

This increases both breathing rate and depth of breathing

33

Exercise

Requires a lot of O2 and produces a lot of CO2

This increases breathing rate and depth of breathing

34

Regulating Blood Sugar

= the amount of Glucose in the blood

35

The Liver

Glucose in the blood travels straight to the liver via the hepatic portal vein

36

The Liver enables Glucose to:

Be removed and to provide energy for liver functioning

Be removed and converted into glycogen for storage

37

Storing Glucose

Liver stores glucose as glycogen through a process called glycogenesis which is stimulated by insulin (secreted by the pancreas)

38

Using Glycogen

Glycogen is converted to glucose via glycogenolysis which is stimulated by glucagon

39

Pancreas

Contains hormone secreting cells known as islets of langerhan

Alpha - secretes glucagon
Beta - secretes insulin

40

Insulin in Pancreas

1. Causes increased uptake of glucose from the blood

2. Promotes the conversion of glucose to glycogen

3. Increases protein synthesis

41

Glucagon in Pancreas

1. Causes an increase in blood sugar

2. Stimulates glycogenolysis

3. Stimulates liver to produce new sugar molecules from fats and amino acids through gluconeogenesis

42

Adrenal Cortex

Secretes Glucocorticoids from the adrenal cortex which is stimulated by the adrenocorticotropic hormone from the anterior lobe of the pituitary gland

It regulates carbohydrate metabolism to make sure there is enough energy for the cells

43

Adrenal Medulla

Secretes Adrenaline and Noradrenaline

44

Adrenaline and Noradrenaline

Increase blood sugar levels by stimulating the production of lactic acid from glycogen in muscle cells

45

Glucose

Simplest form of sugar

46

Glycogen

Stored form of glucose

47

Insulin

Decreases of blood glucose levels

48

Glucagon

increase of blood glucose level

49

Glycogenesis

Process of creating glycogen from glucose

50

Glycogenolysis

Process of creating glucose from glycogen

51

Lipogenesis

Creates fats from glucose in adipose tissue

52

Gluconeogenesis

Creating new glucose molecules from lipids and amino acids