Homeostasis

Question 1

Homeostasis

Answer 1

regulation of conditions inside the body to maintain a stable internal environment in response to both internal and external conditions.

Question 2

Negative Feedback

Answer 2

The response eradicates/reduces the stimulus

Question 3

Positive Feedback

Answer 3

The response intensifies the stimulus e.g. childbirth

Question 4

Stimulus

Answer 4

A change in the environment

Question 5

Receptor

Answer 5

Detects change in environment

Question 6

Modulator

Answer 6

Interprets the message and initiates a response

Question 7

Effector

Answer 7

Muscle or gland that carries out the response

Question 8

Feedback

Answer 8

Change in original stimulus

Question 9

Conduction

Answer 9

Transfer of heat through contact

Question 10

Convection

Answer 10

Liquid or gas rises from the skin

Question 11

Radiation

Answer 11

Transfer of heat through electromagnetic radiation

Question 12

Evaporation

Answer 12

Transfer of heat as liquid moves into a gas phase

Question 13

Physiological Response to cold

Answer 13

• Piloerection
• Shivering
• Thyroxine (metabolic rate)
• Adrenal Medulla (cellular respiration)
• Behavioural
• Vasoconstriction

Question 14

Physiological Response to Heat

Answer 14

• Pilorelaxation
• Sweating
• Thyroxine (metabolic rate)
• Behavioural
• Vasodilation

Question 15

Role of the Liver in blood glucose regulation

Answer 15

Converts glucose into glycogen and glycogen into glucose (blood passes through the hepatic portal vein)
Four Options:
- Can be removed from the bloodstream and stored as glycogen in the liver
- Can continue circulating, fueling other body cells
- Can be removed to fuel the liver
- Excess glucose is converted into fat
Liver glycogen can then be released or used for the liver’s activities

Question 16

Role of the pancreas; Alpha Cells

Answer 16

Secretes Glucagon (raises blood sugar)
Three ways:
- Stimulates Glycogenolysis (breakdown of glycogen into glucose)
- Stimulates Gluconeogenesis (production of glucose from amino acids, fats)
- Promotes protein breakdown, freeing amino acids for gluconeogenesis

Question 17

Role of pancreas; Beta Cells

Answer 17

Produces Insulin (lowers blood sugar)
Four Ways:
- Promotes the uptake of glucose into cells
- Increases rate of glycogenesis (production of glycogen from glucose)
- Increases the rate of fat production from glucose
- Promotes protein synthesis (decreasing gluconeogenesis)

Question 18

Role of Adrenal Glands; Adrenal Cortex

Answer 18

Stimulated by Adrenocorticotrophic Hormones and release Cortisol, which regulates carbohydrate metabolism, stimulating glycogenolysis and increasing gluconeogenesis

Question 19

Role of Adrenal Glands; Adrenal Medulla

Answer 19

Stimulated by the sympathetic nervous system, secreting Adrenaline and Noradrenaline, which increases cellular metabolism and therefore blood sugar levels.

Question 20

Urine Formation

Answer 20

Filtration (Renal Corpusle)
Selective Reabsorption (PCT, LH, DCT)
Tubular Secretion (PCT, DCT)
- Only water loss source that can be regulated
NEPHRON IS EFFECTOR

Question 21

Reabsorption of Water

Answer 21

60-70% of water reabsorption occurs in the PCT
30-40% is selective reabsorbed in the LH, DCT, CD
Reabsorption in DCT is active transport

Question 22

Osmoreceptors

Answer 22

Located in thirst centre of the Hypothalamus
- If blood volume decreases than osmotic pressure is raised
- If blood volume increases than osmotic pressure is reduced

Question 23

Role of ADH

Answer 23

Thirst centre in hypothalamus stimulates the release of ADH from the posterior pituitary gland.
ADH targets the DCT and CT increasing their permeability causing more water to be absorbed in the blood plasma.

Question 24

Role of Aldosterone

Answer 24

Promotes reabsorption of sodium from the urine

Question 25

Dehydration

Answer 25

Increased osmotic pressure
Triggers thirst reflex and individual drinks water which is then absorbed.

Question 26

Diaphragm

Answer 26

COntrolled by the phrenic nerve

Question 27

Intercostals

Answer 27

Controlled by the intercostal nerves

Question 28

Expiratory centre in the Medulla Oblongata

Answer 28

COntrols breathing out
Sends impulses to the Internal intecostals

Question 29

Inspiratory centre in the Medulla Oblongata

Answer 29

Controls breathing in
Sends impulses to the diaphragm and external intercostals

Question 30

Central Chemoreceptors

Answer 30

In the medulla oblongata
Control CO2 concentrations, and ph of blood plasma and cerebrospinal fluid
Delayed response
More sensitive
Responsible for the majority of control of breathing

Question 31

Peripheral Chemoreceptors

Answer 31

In aortic and carotid bodies
Measures changes in ph (hydrogen ion concentration and CO2 and o2 in blood plasma
Responds quicker due to location
Responds largely to hydrogen ion and co2 levels with breathing rate

Question 31

Hyperventilation

Answer 31

Rapid and deep breathing where the body provides more oxygen and removes more carbon dioxide than neccessary. As the breathing reflex responds to CO2, the person may require o2 levels before co2 levels rise to the point where the body stimulates the breathing reflex

Question 32

Cardiac output

Answer 32

Heart rate x stroke volume
Determines the amount of blood ejected from the heart per minute
- Determines the blood pressure (with diameter of blood vessels)

Question 33

Regulation of heartbeat

Answer 33

Sinoatrial Node
- pacemaker and initiates heartbeat in the right wall of the right atrium
Atrioventricular Node
- regulates beating of ventricles

Question 34

Pressoreceptors

Answer 34

Found in the aorta, right atrium, and right carotid artery

Question 35

Cardiac Centre

Answer 35

In medulla oblongata
connects to SV and AV through sympathetic and parasympathetic nerve fibres