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Physiology Principles Outcomes Flashcards

1
Q

Define tissue.

A

A group of cells with similar structure and specialized function.

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2
Q

Define organ.

A

Two or more types of primary tissues that function together to perform a particular function(s).

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3
Q

Define what is meant by “body system”.

A

Made up of groups of organs that perform related functions, and work together to achieve a common goal(s).

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4
Q

What is required for normal human bodily functions?

A

A stable internal environment, i.e. highly regulated optimum physiological conditions.

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5
Q

Define homeostasis.

A

The maintenance of body systems within certain parameters by coordinated physiological mechanisms.

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6
Q

Why is homeostasis essential for survival?

A

Certain components of the bodies internal environment MUST be maintained within narrow ranges, e.g. temperature.

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7
Q

Define the three types of physiological control systems: Feedforward control, negative feedback control, positive feedback control.

A

Feedforward: responses made in anticipation of a change.

Feedback: responses made after a change has been detected.

Negative feedback: opposes the initial change.

Positive feedback: amplifies an initial change, e.g. uterine contractions.

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8
Q

What is the main type of homeostatic control in the body?

A

Negative feedback.

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9
Q

How does negative feedback promote stability within the body?

A

Regulates a controlled variable through a flow of information along a closed loop.

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10
Q

Explain the components of a negative feedback control system.

A

Made up of:

  1. A sensor. Detects changes to a controlled variable.
  2. Control centre. This compares the sensor’s information with a set point.
  3. Effector(s). This carries out a response to produce a desired effect.
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11
Q

What might disruption of homeostasis result in?

A

Disease or death.

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12
Q

List the major components of a cell plasma membrane.

A

Phospholipids forming a lipid bilayer.
Proteins.
Carbohydrates.

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13
Q

Describe how the various membrane components are arranged.

A

Lipid bilayer forms the cell membrane. Membrane proteins may be integral (span/embedded/linked to lipid component of bilayer) or peripheral (adhere to cytoplasmic or extracellular surface of membrane).

Carbohydrates may attach to membrane. Or to membrane proteins, glycoproteins or glycolipids to form a layer called the glycocalyx.

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14
Q

Explain how the membrane is influenced by the presence of cholesterol.

A

Cholesterol stiffens the membrane.

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15
Q

Describe integral membrane proteins.

A

Integral membrane proteins may span the lipid bilayer, embed in it or link to a lipid component. They can be ligand-binding receptors, adhesion molecules, pores/channels, carriers or pumps. They may also be enzymes or participate in intracellular signaling.

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16
Q

Proteins are molecules of biological specificity, and give distinctive properties on the cellular membranes in which they occur. What does this lead to amongst cell types?

A

Diversity.

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17
Q

How does diffusion differ in a solution, and through a membrane?

A

In a solution, diffusion occurs from the area of high solute concentration, to the area of low solute concentration.

Diffusion through a membrane occurs only if a substance is able to permeate the membrane.

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18
Q

Explain Fick’s Laws of diffusion.

A

The rate of diffusion is directly proportional to the membrane surface area and the concentration gradient.

It is inversely proportional to the membrane thickness.

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19
Q

How can rates of diffusion be altered?

A
  1. Magnitude of concentration gradient.
  2. Surface area of the membrane.
  3. Substance’s lipid solubility.
  4. Molecular weight of the substance.
  5. Distance through which diffusion must occur.
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20
Q

Define electrochemical gradient.

A

A difference in charge between two adjacent areas, generating an electrical gradient that promotes movement of ions toward the area of opposite charge.

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21
Q

Define osmosis.

A

The net diffusion of water down its own concentration gradient through a selectively permeable membrane.

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22
Q

Define osmolarity.

A

Osmolarity is the concentration of osmotically active particles present in a solution.

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23
Q

Define tonicity.

A

Tonicity is the effect a solution has on cell volume.

I.e. iso- (no net movement), hypo- (water moves into cells) or hyper-tonic (water moves out of cells).

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24
Q

List three important characteristics of carrier mediated transport.

A
  1. Specificity. Each carrier is specialized to transport a specific substance.
  2. Saturation.
  3. Competition. Ability to transport more than one substance.
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25
Q

Define facilitated diffusion.

A

Use of a carrier to facilitate the transfer of a substance across the membrane from a high, to a low concentration.

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26
Q

Define active transport.

A

Carrier is required to expend energy to transfer a substance against an existing concentration gradient.

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27
Q

Define primary active transport.

A

Energy is directly required.

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28
Q

Define secondary active transport.

A

Energy is required, but is not used to directly produce movement. Instead, energy in the form of an ion concentration gradient is used.

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29
Q

What is the stoichiometry of the Na+ /K+ pump?

A

3 Na+ are transported out of the cell for every 2 K+ transported in.

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30
Q

Name 3 important physiological roles of the Na+/K+ pump.

A
  1. Helps establish Na+ and K+ concentration gradients across plasma membranes of cells.
  2. Helps regulate cell volume by controlling solute concentrations inside cells.
  3. Energy used to drive the pump indirectly serves as the energy source for secondary active transport.
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31
Q

Name and explain two types of vesicular transport.

A

Endocytosis: “pinching off” of membrane to engulf a substance.

Exocytosis: Vesicle fused with the plasma membrane, releasing its contents into ECF.

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32
Q

Describe the Baroreceptor Reflex.

A

The baroreceptor reflex detects deviations in a controlled variable, and brings about a compensatory response, resulting in the restoration of the controlled variable to its normal values.

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33
Q

What is the baroreceptors role in regulating mean arterial blood pressure?

A

A deviation in mean arterial pressure is detected by a baroreceptor, which informs the control centre (medulla), instructing effectors (heart and blood vessels) to bring about a compensatory response via the process of negative feedback. This results in restoration of normal mean arterial blood pressure.

34
Q

Define blood pressure.

A

It is the outwards (hydrostatic) pressure exerted by the blood on the walls of blood vessels.

35
Q

Define systolic blood pressure. What is its normal value under resting conditions?

A

Pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart contracts.

<140mmHg.

36
Q

Define diastolic blood pressure. What is its normal value under resting conditions?

A

It is the pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart relaxes.

<90mmHg.

37
Q

define mean arterial blood pressure (MAP).

A

It is the average arterial blood pressure during a single cardiac cycle, which involves contraction and relaxation of the heart.

38
Q

How is mean arterial blood pressure estimated?

A

MAP= [(2x diastolic) + systolic]/3
OR
MAP= diastolic + 1/3 (systolic-diastolic)

39
Q

What is the normal range of mean arterial blood pressure?

A

70-105mmHg.

40
Q

Explain the need for regulation of mean arterial blood pressure.

A

A MAP of at least 60mmHg is needed to perfuse the coronary arteries, brain and kidneys.

Also to ensure pressure is not so high that it damages blood vessels and places strain on the heart.

41
Q

What is mean arterial blood pressure the product of?

A

Cardiac output and total peripheral resistance.

42
Q

Define cardiac output.

A

Cardiac output is the volume of blood pumped by each ventricle of the heart, per minute.

It is the product of stroke volume and heart rate.
CO= SV x HR.

43
Q

Define stroke volume.

A

The volume of blood pumped by each ventricle of the heart, per heart beat.

44
Q

Describe the role of the autonomic nervous system in control of heart rate.

A

Sympathetic division accelerates heart rate via noradrenaline acting on b1 receptors.

Parasympathetic division stimulates the vagus nerve to slow heart rate, via acetylcholine acting on muscarinic receptors.

45
Q

What causes stroke volume to increase?

A

Stroke volume is increased if the hearts contractile strength is increased.

ANS regulates stroke volume via the sympathetic division, which stimulates the ventricular myocardium.

46
Q

What are the main resistance vessels?

A

Arterioles.

47
Q

Define total peripheral resistance. Why are arterioles important to this?

A

TPR is the resistance that must be overcome for blood to flow through the circulatory system.

TPR is regulated by vascular smooth muscles. Vasoconstriction increases TPR and MAP.
Vasodilatation decreases TPR and MAP.

48
Q

Describe the principles underlying the control of total peripheral resistance by the autonomic nervous system.

A

Vascular smooth muscles are supplied by sympathetic nerve fibres (noradrenaline acting on alpha receptors).

49
Q

Arterial and arteriolar smooth muscles are mainly supplied by which type of nerves?

A

Sympathetic.

50
Q

What is vasomotor tone?

A

At rest vascular smooth muscles are partially constricted = VASOMOTOR TONE. This is caused by tonic discharge of sympathetic nerves resulting in continuous release of noradrenaline.

51
Q

What effect does increased & decreased sympathetic discharge have on TPR?

A

Increased sympathetic discharge increases vasomotor tone -> vasoconstriction, causing increased TPR and MAP, and vice versa.

52
Q

Do baroreceptors respond to sustained high blood pressure? Explain.

A

No. They respond only to acute changes. If high BP is sustained, their rate of firing decreases, and they “re-set”.

They fire again, only if there is an acute change above the new higher steady state level.

53
Q

State approximate values for the sodium, potassium and chloride ion concentrations inside and outside the cell.

A

Sodium
Intracellularly: 15mM
Extracellularly:150mM

Potassium:
Intracellularly: 150mM
Extracellularly: 5mM

Chloride:
Intracellularly: 7mM
Extracellularly: 110mM

54
Q

State the relative membrane permeabilities of sodium and potassium ions.

A

Sodium: 1
Potassium: 100 (in skeletal muscle cells)

55
Q

Define the term equilibrium potential.

A

Equilibrium potential is the membrane potential at which an ion will not diffuse through a membrane in either direction.

56
Q

State approximate values for sodium and potassium equilibrium potentials.

A 
EK= -90mV.
ENa= +60mV.
57
Q

State the resting membrane potential for a typical nerve cell.

A

-70mV.

58
Q

Explain why the resting membrane potential and potassium equilibrium potential are not identical.

A

Em is membrane potential, i.e. the difference in charges across a membrane (mV).

EK is equilibrium potential, i.e. the membrane potential at which an ion will not diffuse through a membrane in either direction.

59
Q

Why is membrane potential important, particularly in excitable cells?

A

Enable flow of ions through the membrane.

Excitable cells (nerves and muscle) have the ability to produce rapid, transient changes in membrane potential when excited (action potentials).

60
Q

Why is glucose important as a metabolic fuel?

A

The brain is a glucose obligate tissue. Hypoglycaemia can lead to confusion, or a coma if untreated (“4 is the floor”).

61
Q

List 5 hormones that influence glucose production.

A 
Insulin.
Glucagon.
Adrenaline (in emergencies).
Cortisol.
Growth hormone.
62
Q

Explain the changes in plasma glucose, insulin and glucagon concentrations with time after a meal.

A

After eating, plasma glucose concentration is high.

Insulin is produced to convert glucose into glycogen.

Glucagon plasma concentration is low, as it is responsible for conversion of glycogen into glucose when in the hungry state.

63
Q

What is the role of the endocrine pancreas in the control of blood glucose?

A

The endocrine pancreas contains the islets of Langerhans. They sense blood glucose levels, and secrete insulin in response.

64
Q

Describe the major physiological actions of insulin & glucagon.

A

Insulin: anabolism. Converts glucose to glycogen.

Glucagon: catabolism. Converts glycogen to glucose.

65
Q

Which tissues are insulin sensitive?

A

Liver, skeletal muscle , adipose tissue and cardiac muscle.

66
Q

Which cells are insulin sensitive?

A

brain, kidney and RBCs.

67
Q

What stimulates and what inhibits insulin release from pancreatic beta cells?

A

Feeding stimulates insulin production by beta cells.

Fasting inhibits insulin release from beta cells.

68
Q

What is Type I diabetes?

A

childhood onset, where there is little/no insulin secretion due to defective b-cell function.

69
Q

What is Type II diabetes?

A

Adult onset (until recently), insulin secretion may be normal or exceed normal, but there is an insulin sensitivity defect.

70
Q

How might diabetes be detected?

A

Glucose tolerance test.

71
Q

What stimulates and what inhibits glucagon release from pancreatic alpha cells?

A

Glucagon release from alpha cells is stimulated only in response to ingested AA proteins.

It is inhibited by glucose.

72
Q

Explain the role of adrenaline in the release of glucose in emergencies.

A

Adrenaline is released from the adrenal gland in response to stress and stimulates glycogenolysis and gluconeogenesis.

73
Q

Explain the roles of cortisol and growth hormone in providing glucose during prolonged fasting.

A

Cortisol is released from the adrenal gland in response to stress.
It stimulates gluconeogenesis.

Growth hormone is released from the anterior lobe of the pituitary gland, in response to starvation. It decreases muscle uptake of glucose and mobilises glucose from the liver.

74
Q

Explain core body temperature.

A

It is the temperature of structures deep within the body. It is homeostatically maintained, despite changes in the environment.

75
Q

Explain normothermia.

A

It is the normal core body temperature optimum for cellular metabolism and function.

76
Q

State the sites for monitoring body temperature.

A

Ear drum (tympanic), rectum, and oral cavity.

77
Q

Define the range of normal values for body temperature and the diurnal variation in body temperature

A

Differs in different individuals, roughly around 37.8oC.

Lowest in early morning.
Altered by other factors throughout the day, e.g. exercise.
Varies during menstrual cycle, higher during second half.

78
Q

Explain how the human body gains or loses heat.

A

Heat may be gained metabolically, from radiation (emission in the form of electromagnetic waves), convection (air currents) or conduction (direct contact, e.g. radiator).

Heat may be lost to the external environment through convection, conduction, radiation or evaporation.

79
Q

How does the human body maintain its core temperature at a set point?

A

homeostatic mechanisms involving a negative feedback control system.

Central thermoreceptors and peripheral thermoreceptors.

The control centre is within the hypothalamus.

The effectors are: skeletal muscle, skin arterioles and sweat glands.

80
Q

Explain how the temperature set point is raised in fever.

A

Macrophages release chemicals in response to infection/inflammation, acting as endogenous pyrogens, i.e. stimulate prostaglandin release from the hypothalamus.

This causes shivering and skin vasoconstriction, raising the body temperature to a new set point, resulting in fever.

81
Q

Distinguish the terms “fever” and “hyperthermia”.

A

Fever raises the hypothalamic temperature set point.

Hyperthermia is the extreme uncontrolled increase in body temperature, i.e. >40oC.

82
Q

Define hypothermia.

A

A drop in body temperature below that required for cellular metabolism and function, i.e. <35oC.

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