Homeostasis Flashcards

1
Q

Homeostasis

A

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

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2
Q

Negative Feedback

A

The response eradicates/reduces the stimulus

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3
Q

Positive Feedback

A

The response intensifies the stimulus e.g. childbirth

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4
Q

Stimulus

A

A change in the environment

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5
Q

Receptor

A

Detects change in environment

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6
Q

Modulator

A

Interprets the message and initiates a response

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7
Q

Effector

A

Muscle or gland that carries out the response

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8
Q

Feedback

A

Change in original stimulus

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9
Q

Conduction

A

Transfer of heat through contact

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10
Q

Convection

A

Liquid or gas rises from the skin

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11
Q

Radiation

A

Transfer of heat through electromagnetic radiation

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12
Q

Evaporation

A

Transfer of heat as liquid moves into a gas phase

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13
Q

Physiological Response to cold

A
  • Piloerection
  • Shivering
  • Thyroxine (metabolic rate)
  • Adrenal Medulla (cellular respiration)
  • Behavioural
  • Vasoconstriction
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14
Q

Physiological Response to Heat

A
  • Pilorelaxation
  • Sweating
  • Thyroxine (metabolic rate)
  • Behavioural
  • Vasodilation
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15
Q

Role of the Liver in blood glucose regulation

A

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

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16
Q

Role of the pancreas; Alpha Cells

A

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

17
Q

Role of pancreas; Beta Cells

A

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)

18
Q

Role of Adrenal Glands; Adrenal Cortex

A

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

19
Q

Role of Adrenal Glands; Adrenal Medulla

A

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

20
Q

Urine Formation

A

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

21
Q

Reabsorption of Water

A

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

22
Q

Osmoreceptors

A

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

23
Q

Role of ADH

A

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.

24
Q

Role of Aldosterone

A

Promotes reabsorption of sodium from the urine

25
Dehydration
Increased osmotic pressure Triggers thirst reflex and individual drinks water which is then absorbed.
26
Diaphragm
COntrolled by the phrenic nerve
27
Intercostals
Controlled by the intercostal nerves
28
Expiratory centre in the Medulla Oblongata
COntrols breathing out Sends impulses to the Internal intecostals
29
Inspiratory centre in the Medulla Oblongata
Controls breathing in Sends impulses to the diaphragm and external intercostals
30
Central Chemoreceptors
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
31
Peripheral Chemoreceptors
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
31
Hyperventilation
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
32
Cardiac output
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)
33
Regulation of heartbeat
Sinoatrial Node - pacemaker and initiates heartbeat in the right wall of the right atrium Atrioventricular Node - regulates beating of ventricles
34
Pressoreceptors
Found in the aorta, right atrium, and right carotid artery
35
Cardiac Centre
In medulla oblongata connects to SV and AV through sympathetic and parasympathetic nerve fibres
36