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Flashcards in Physiology Deck (52)
1

What are the components of a phospholipid?

Hydrophobic tail + hydrophilic head

2

Bonds between phospholipids are strong. True/False?

False
Bonds are weak - explains the fluid nature of the membrane

3

Cholesterol contributes to which two aspects of the membrane?

Fluidity and stability

4

What are the 3 main types of proteins found on the membrane?

Integral (receptors)
Transmembrane (channels, transporters)
Peripheral (enzymes)

5

The glycocalyx layer is formed by...

Short carbohydrate chains bound to proteins and lipids

6

What are desmosomes?

Adhering junctions that anchor cells together

7

What are tight junctions?

Join lateral edges of epithelial cells near their apical membranes

8

What are gap junctions?

Communicating junctions that allow movement of charge between adjacent cells

9

2 main factors that influence whether a particle can passively permeate the membrane

Lipid solubility (non-polar pass easily)
Size

10

Diffusion is movement from ___ to ___ concn

High to low

11

Fick's law of diffusion describes the rate of net diffusion and is made up of...

Magnitude of concn gradient
SA available for diffusion
Lipid solubility and size/weight of substance
Distance over which diffusion must occur

12

Osmolarity is defined as...

The number of osmotically active particles present in a solution

13

How is osmolarity calculated?

Using molar concn (mM) and number of osmotically active particles (n)

14

150mM NaCl has osmolarity = ?

150 x 2 (Na+ and Cl-) = 300mOsm

15

A hypotonic solution will ____ in cell volume

Increase (needs mOre water)

16

Facilitated diffusion requires energy. True/False?

False

17

Active transport transfers a substance from high to low concn. True/False?

False
Low to high

18

_ Na+ out for every _ K+ in with regards to Na-K pump

3, 2

19

Secondary active transport occurs by which 2 mechanisms? Define them

Symport (co-transport): solute and ion move in same direction
Antiport: solute and ion move in opposite directions

20

Membrane potential (Em) arises due to...

Separation of opposite charges across the membrane

21

At resting potential, the membrane is 100x more permeable to sodium than potassium. True/False?

False
100x more permeable to K+ than Na+

22

Em for K+ is approx...

-90mV

23

Em for Na+ is approx...

+60mV

24

Nernst equation

Eion = 61log[ion]o / [ion]i

25

Membrane potential is much closer to the potential of Na+ ions. True/False?

False
Much closer to Ek+ due to greater permeablity of K+

26

Em for a typical nerve cell at rest = ?

-70mV

27

GHK equation (used to calculate membrane resting potential)

Em = 61log x PK+[K+]o + PNa+[Na+]o / PK+[K+]i + PNa+[Na+]i

28

Which receptors control mean arterial BP? Where are the receptors, control centre + effectors located?

Baroreceptors, located in aortic arch + carotid sinus
Control centre: medulla oblongata
Effectors: heart + blood vessels

29

Normal range for MAP?

70-105 mmHg

30

Formulae for calculating MAP?

MAP = [(2x diastolic) + systolic]/3
MAP = diastolic + [systolic - diastolic]/3
MAP = CO x TPR

31

MAP of at least __ mmHg is needed to perfuse coronary arteries, brain and kidneys

60 mmHg

32

Firing rate in baroreceptors ____ when MAP increases

Increases
(sensitive to stretch: when you stretch them, firing increases)

33

Cardiac output (CO) is...

The volume of blood pumped out by each ventricle per minute (SV x HR)

34

Stroke Volume (SV) is...

Volume of blood pumped out by each ventricle per heart beat

35

Increasing contractile strength of the heart causes stroke volume to ____

Increase

36

Vasomotor tone is described as...

Vascular smooth muscle being constricted at rest

37

Normal blood glucose level

Around 5 mmol/l

38

In the absorptive + post-absorptive states, which hormones control [glucose]p

Insulin and glucagon

39

In emergencies, which hormone control [glucose]p

Adrenaline

40

In starvation, which hormones control [glucose]p

Cortisol, GH

41

In pancreatic islet cells, _ cells release glucagon, _ cells release insulin and _ cells release somatostatin

alpha, beta, delta

42

Insulin lowers [glucose]p by...

Stimulating uptake of glucose by muscle and fat cells
Activating liver enzymes to convert glucose into glycogen

43

Diabetics can increase GLUT4 expression by doing what?

Exercising

44

Glucagon increases [glucose]p by...

Increasing glycogenolysis/inhibiting glycogen synthesis

45

Cortisol increases [glucose]p by...

Stimulating protein catabolism, lypolysis and gluconeogenesis

46

Core body temperature is about...

37.8'C

47

Basal metabolic rate is defined as...

The minimum amount of energy required to sustain body functions

48

Which receptors monitor body heat? Where are they, the control centre and effectors located?

Thermoreceptors, located in the hypothalamus and skin
Control centre: hypothalamus
Effectors: skeletal muscles, skin arterioles, sweat glands

49

The posterior hypothalamus is activated by cold. True/False?

True

50

Fever is temperature between...

38-40'C

51

Hyperthermia is temperature...

> 40'C

52

Hypothermia is temperature below...

35'C