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Flashcards in Principles Deck (55):
1

What is the nema of the mechanism that allows te heart to been rythmically in the absence of external stimuli?

Autorhythmicity

2

What does the sympathetic division do to heart rate?

It accelerates the heart rate

3

What receptors does noradrenaline act on?

B1 receptors

4

What does the paraympatheic division do to heart rate?

Stimulates the vagus nerve Xth cranial nerve and slows the heart rate

5

What receptors does acetylcholine act on?

Muscarinic Receptors

6

What is stroke volume modified by?

The autonomic nervous system

7

What law controls the stroke volume intrinsically?

The Frank starling Mechanism

8

What is metabolism?

All the chemical reactions that occur within the cells of the body

9

What is fuel metabolism (intermediary metabolism)

Reactions involving catabolism, anabolism and transformation of protein, carbohydrate (CHO) and fat

10

How is fuel metabolism regulated?

By hormones;

  • insulin
  • glucagon
  • adrenaline
  • growth hormone

 

Thyroid hormone regulates metabolic rate.

11

What hormones control plasma glucose?

 

  • in the absorptive and post-absorptive states: insulin and glucagon (pancreas)
  • in emergencies: adrenaline (adrenal gland)
  • during starvation: cortisol (adrenal), growth hormone (pituitary)

12

what are the two kinds of glands in the pancreas?

  1. exocrine glands (Secrete digestive enzymes and 1.HCO3- into the intestinal lumen)
  2. Endocrine glands(Islets of Langerhans)

13

What kinds of secretory cells do islets contain?

1.Alpha (a) cells (glucagon)

2.Beta (b) cells (insulin, proinsulin, C peptide and amylin)

3.Delta (d) cells (somatostatin)

4.F cells (pancreatic polypetide – role, if any, in fuel metabolism is not clearly understood)

 

14

What is the function of insulin

Favours anabolism

Stimulates conversion of glucose into glycogen, fatty acids into triglycerides and amino acids into protein

Insulin is the hormone of the fed-state

15

what is the function of glucagon?

  • favours catabolism
  • stimulates conversion of glycogen into glucose and triglycerides into fatty acids
  • glucagon is the hungry hormone

16

What is the role of insulin during feeding?

  • beta cell secretes more insulin
    • catabolism of endogenous fuel stores is inhibited
    • CHO, lipid and AA uptake by specific insulin-sensitive tissues is stimulated
    • insulin directs tissues to replenish fuel reserves

17

What is the role of insulin during fasting?

  • beta cell secretes less insulin
    • lipids are mobilised from adipose tissue 
    • amino acids (AAs) are mobilised from muscle and other tissues
    • lipids and AAs provide fuel for oxidation and act as precursors for hepatic ketogenesis and gluconeogenesis respectively 

18

What is the major regulator of insulin secretion?

Glucose

modest increases in plasma glucose promote marked increases in insulin secretion and marked increases in plasma insulin

19

What innervates an Islet?

both the sympathetic and parasympathetic divisions of the ANS

20

What does parasympathetic stimulation and sympathetic stimulation do to insulin secretion?

parasympathetic- stimulates insulin secretion during feeding

sympathetic- inhibits insulin secretion

21

What are the three identified peptides (incretins) which enhance insulin secretion?

1.CCK (cholecystokinin)

2.GLP-1 (glucagon-like intestinal peptide 1)

3.GIP (gastric inhibitory peptide)

22

where are insulin incretins released from?

All 3 are released by cells in the GI tract in response to feeding and act in a feed-forward manner to prime the beta cells to secrete insulin

23

what are the three principle target tissues for insulin?

  • liver
  • skeletal muscles
  • adipose tissue

24

which cells are insulin insensitive?

brain, kidney, RBCs

 

25

Where is glycogen stored?

Liver and skeletal muscle (little in adipose tissue)

26

How does the liver lower glucose concentration?

by activating enzymes, promoting the storage of fats as triglycerides and inhibiting the oxidation of fatty acids. 

It also stimulates the synthesis of protein and simultaneously reduces the degradation of protein in the liver

27

How does insulin lower glucose concentration in skeletal muscle and adipose tissue?

  • stimulating uptake of glucose from the blood into skeletal muscle and fat cells (GLUT4) 
  • increases glucose breakdown and oxidation (Cells diminish fat utilisation, fatty acids stores as triglycerides)
  • stimulates protein synthesis and slows protein degradation (preservation of protein mass)

28

what cells does type 1 diabetes effect?

B cell function

29

How are ketone bodies produced in DM?

If untreated the metabolism of fatty acids as a compensatory energy source generates acetyl-CoA. The liver cant process acetyl-CoA through the citric acid cycle and ketone bodies are formed. 

30

What is glucagon secreted as a response to and from where?

Response to ingested protein (AAs) from pancreatic alpha cells

31

What is the target tissue of glucagon? and what is it responsible for?

The liver, regulates hepatic CHO and lipid metabolism

It stimulates;

  • glyconeogenesis
  • gluconeogenesis 
  • ketogenesis

32

What does glucagon stimulate in skeletal and cardiac muscle?

What does glucagon stimulate in adipose tissue?

Glyconeogenesis

Lipolysis

33

What are adrenaline and cortisol released as a response to?

stress

34

What does adrenaline stimulate and when is it released?

Glyconeogenesis and gluconeogenesis

In short-term emergencies

35

When is cortisol released and what does it stimulate?

Not important for rapid mobilisation of fuel

Stimulates protein catabolism, gluconeogenesis, lipolysis

36

Where is the growth hormone secreted from?

The anterior lobe of the pituitary gland

37

What is the relevance of growth hormone in starvation?

Decreases glucose uptake by muscle

Mobilises glucose from liver

promotes lipolysis in fat cells

38

what is homeostatic core temperature maintained around?

37.8 degrees celcius

39

What does increased core temperature do to cellular metabolism?

It increases the rate

40

What does overheating cause?

  • protein denaturation
  • nerve malfunction
  • convulsions
  • death

41

What are the sites for monitoring body temperature and what are there normal ranges?

Ear drum (tympanic)- 35.5-37.5

Rectal- 36.7-37.5

Oral: not accurate 

42

What is the term for body temperature varying throughout the day?

Diurnal variation

43

What factors influence body temperature?

  • activity
  • emotions
  • exercise
  • exposure
  • may be higher during the 2nd half of female menstrual cycle

44

What is BMR?

Basal Metabolic Rate- minimum amount of energy requires to sustain vital body functions and lead to a basic level of heat production

45

How does muscle activity alter heat?

Increased activity= increased heat production eg shivering

46

How is heat exchanged with the external environment

radiation (around 1/2)

conduction (warmer to cooler)

convection (combines with conduction to dissipate heat- air reliant)

evaporation (occurs continuously, not subjected to physiologic control, humidity of atmosphere effects it)

 

47

How does the human body maintain its core temperature?

 

Negative feedback control systems

48

what are the control centres of temperature?

  • hypothalamus
  • abdominal organs
  • peripheral thermoreceptors in skin

49

What are the effectors of temperature control?

skeletal muscles

skin arterioles

sweat glands

behaviour adaptations

50

What are the neural inputs to the hypothalamus?

The negative feedback receptors for temperature regulation

It has connections with the limbic system & cerebral cortex, the motor neurons which controls the skeletal muscles and the sympathetic nervous system

51

Which parts of the hypothalamus are activated by watmth and cold respectively?

anterior hypothlamic centre

posterior hypothalamic centre

52

What do chemicals released from macrophages in response to infection or inflammation act as?

They act as endogenous pyrogens (eg interleukins), stimulating the release of prostaglandins in the hypothalamus.

53

What do prostaglandins do?

Act on the hypothalamic thermo-regulatory centre to 'reset' the thermostat at a higher temperature

54

What temperatures are hyperthermia and hypothermia?

above 40

below 35

55