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HOM > Miscellaneous > Flashcards

Miscellaneous Flashcards

1
Q

Define regulated variable

A

Any variable that is kept within certain limits by a homeostatic mechanism

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2
Q

Define sensor

A

A mechanism that measures a variable and generates an output signal proportional to its magnitude

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3
Q

Define set point

A

Range of values that the system attempts to maintain

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4
Q

Error detector

A

Computes difference between the set point and actual values and generates an error signal

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5
Q

Control centre

A

Combination of an error detector and controller that generates an out put signal to change an effector’s activity

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6
Q

Effector

A

A mechanism that contributes to determining the value of the regulated variable

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7
Q

Blood pressure

Give the:

a) regulated variable
b) sensors
c) control centre
d) effectors
e) response

A

a) Mean arterial pressure
b) mechanosensors In aorta and neck
C) medulla oblongata
d) heart and blood vessels
e) heart rate, contraction, peripheral resistance

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8
Q

Blood oxygen

Give the:

a) regulated variable
b) sensors
c) control centre
d) effectors
e) response

A

Arterial PO2

Chemoreceptors in aortic and carotid bodies

Brain stem

Diaphragm and respiratory muscles

Breathing frequency and depth

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9
Q

Blood glucose

Give the:

a) regulated variable
b) sensors
c) control centre
d) effectors
e) response

A

Blood glucose concentration

Islets of Langerhans

Pancreas

Liver, adipose tissue, skeletal muscle

Alter storage/ metabolism/ glucose release

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10
Q

Body temperature

Give the:

a) regulated variable
b) sensors
c) control centre
d) effectors
e) response

A

Core body temperature

Thermosensors in hypothalamus

Hypothalamus

Blood vessels, sweat glands, skeletal muscle

Change skin vessel resistance, sweat secretion, shivering

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11
Q

Problems with negative feedback

A

Slow response

Variable must change before effector responds resulting in oscillations and instability

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12
Q

What is a feedforward mechanism

A

Anticipatory response: producing an effector response before regulated variable changes

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13
Q

What does the posterior pituitary secrete

A

ADH and oxytocin

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14
Q

What is the fastest nerve conduction velocity

What is typical nerve conduction velocity

A

120m/s

50m/s

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15
Q

What do primary active transporters use

A

ATP

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16
Q

Where is glycine used

A

In the spine

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17
Q

Where is GABA found

A

The brain

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18
Q

Name inhibitory NT

A

Glycine

GABA

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19
Q

When does the length of A band change

A

Never

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20
Q

What is mean pulmonary arterial pressure

A

15mmHg

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21
Q

What is the ratio of capillaries: heart cells

A

1:1

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22
Q

What is the site of definitive hematopoiesis

A

Bone marrow

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23
Q

What colour is active bone marrow

A

Red colour

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24
Q

What is function of thymus

A

Selects lymphocytes that react with non self and not self

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25
Q

Give 4 key functions of the blood

A

Transport of nutrients, gases, hormones, waste

Restriction of fluid loss during injury

Defence from infection

Homoeostasis

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26
Q

What is hemostasis

A

Restriction of fluid loss

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27
Q

What are the 2 routes of transport across the capillary endothelial cell layer

A

Para cellular

Trans cellular

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28
Q

Describe the paracellular route of transport through capillary endothelium

A

Water and small solutes pass through the paracellular which this transport mode is limited by tight junctions and gap Junctions

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29
Q

Describe the transcellular route through endothelium

A

Larger sockets pass through this route either via a) receptor-mediated endocytosis or B) Trancytosis C) trans-endothelial channels such as vesicular vacuolar organelles

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30
Q

What are VVOs

A

Interconnected vesicles forming channels across the cell

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31
Q

Describe transcytosis

A

When cells take up extra cellular medium through caveolae-mediated macro pinocytosis and transfer to the opposite side of the cell

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32
Q

Where is fenestrated endothelium found

A

GI tract
Glomerulus
Endocrine cells

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33
Q

Describe the endothelium of the liver

A

It is discontinuous

Characterised by fenestrae without diaphragms and poorly organised basement membranes

These endothelial cells have a high level of clathrin mediated receptor endocytosis increasing their ability to take up specific molecules

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34
Q

Describe continuous nonfenestrated endothelium

A

Water and small solutes pass in between cells where as larger solutes pass through the cells via trans-cytosis

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35
Q

Where is the permeability of endothelium especially restricted

A

Brain

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36
Q

What forms the blood brain barrier (3)

A

Tighter endothelial junctions

Thicker basement membrane

A layer of supporting astrocytes

37
Q

What does the BBB allow through (5)

A 
Water
Gases
Lipid soluble hormones 
Glucose
Some αα
38
Q

How does the BBB prevent the entry of lipophilic potential neurotoxins

A

An active transport mechanism mediated by P – glycoprotein

39
Q

Why are brain pathogens hard to treat

A

Antibodies are too large to cross the blood brain barrier and only certain antibiotics are able to pass

40
Q

How do endothelial cells facilitate inflammation

A

Increase permeability so that plasma proteins and neutrophils can exit and reach the tissue/site of infection.

41
Q

Do you fish and reptiles have enucleated RBCs

A

No

42
Q

What could the loss of the nucleus in Mammalian red blood cells be related to

A

A larger genome in relation to body size and smaller diameter of capillaries

43
Q

What does a pulse oximeter do

A

Measures blood oxygenation by comparing the different absorption of oxy Hb and deoxy Hb

44
Q

Where does erythropoiesis occur in

a) adults
b) foetus

A

a) bone marrow

b) liver and spleen

45
Q

How do RBC progenitor cells differentiate

How are old RBCs destroyed

A

They progressively differentiate into red blood cells losing the nucleus, ribosomes and organelles

By macrophages in the liver or spleen

46
Q

Discuss EPO (3)

A

Erythropoietin

Produced in the kidney and regulated by negative feedback

Low oxygen stimulates the release of EPO, stimulating release of RBCs

Resulting high oxygen levels suppress production of EPO

47
Q

What is the hypoxia response regulated by

A

Hif α

hypoxia inducing factor

48
Q

What happens to Hif α in normoxia

What happens in hypoxia

A

Hydroxylated, leading to degradation

The activity of hydroxylases is reduced and HIF α can activate transcription of EPO

49
Q

Why is destruction of RBCs important

A

Damaged RBCs release haemoglobin and iron which are sequestered in the kidney causing inflammation and damage

50
Q

Name the 3 granulocytes

A

Neutrophils
Eosinophils
Basophils

51
Q

Name the 4 agranulocytes I

A

T lymphocytes
B lymphocytes
Monocytes
Megakaryocytes

52
Q

Discuss neutrophils (3)

A

Granules are visible with neutral dies

Crucial for a bacterial infections

Most abundant cells in the blood

53
Q

discuss eosinophils

A

Granules are visible with acidic days

Play a role in parasitic infections

Granules contain peroxides and enzymes toxic to parasites

54
Q

Discuss basophils

A

Granules are visible with basic ties

Produce histamine and heparin

Play a role in allergy

55
Q

What do a) T and b) B lymphocytes do

A

a) kill infected cells or produce signals that assist function of other immune cells
b) produce antibodies

56
Q

What are natural killer cells

A

They kill ourselves through different mechanisms, important for antitumour responses

57
Q

What do monocytes do

A

Differentiate into other cells that can mediate phagocytosis and activation of T cells

Most tissues have resident macrophages and dendritic cells but monocyte serve as a reserve pool to supply more of the cells upon infection

58
Q

What can monocytes differentiate into

A

Macrophages and dendritic cells

59
Q

What are megakaryocytes

A

They are large multinucleated cells whose segmentation gives rise to platelets

Important for haemostasis

60
Q

What happens after a vessel is injured

A

A vascular spasm
Platelets aggregate at the site Foreman a plug to seal the wound

Release of factors from platelets trigger the coagulation reaction and a fibrin mesh forms

61
Q

What is a vessel spasm

A

A decrease in diameter of vessel by muscle contraction

62
Q

What factors are released from platelets (3)

What do they do

A

ADP
Serotonin
Prostaglandin

Trigger the coagulation reaction, whereby fibrinogen is converted into fibrin by thrombin to form a gelatinous mash that provides a stable seal for the wound

63
Q

What happens to the fibrinous mesh once the vessel wound is healed

A

Fibrinolysis follows

Plasminogen has to be converted into plasmin, which breaks down fibrin

Bradykinin relaxes the muscles and restores bloodflow

64
Q

Give 4 functions of the lymphatic system

A

Returns interstitial fluid and plasma proteins to blood

Filters blood by removing harmful agents like toxins and microbes

Provides a structural basis for the immune system

Transports dietary lipids from the gastrointestinal tract to blood

65
Q

Is the lymphatic system a closed circulation

A

No it is 1 way

66
Q

Which is higher: hydrostatic or osmotic capillary pressure

Which are more permeable: lymphatic or blood vessels

A

Hydrostatic

Lymphatic

67
Q

3 things that facilitate lymph flow

A

Breathing
Exercise
Good posture

68
Q

Where does the thoracic duct enter into

A

Subclavian vein

69
Q

What is elefantiasis

A

Parasitic infection (helminth) of the lymphatic system

Causes oedema

70
Q

3 cells present in lymph

A

Lymphocytes

Macrophages

Dendritic cells

71
Q

Where are B and T cells produced

A 
B= bone marrow
T= thymus
72
Q

What do macrophages and dendritic cells do

A

Macrophages: clear dead cells

Dendritic cells: activate T cells

73
Q

What are the secondary lymphoid organs

A

Lymph nodes
Spleen
Gut lymphoid

74
Q

How many blood cells are produced a day

A

500 billion

75
Q

Why does haematopoiesis decrease with age

A

Replacement of haematopoietic tissue with fat

It decreases faster in Lower limbs

76
Q

What colour is fat

A

Yellow

77
Q

How many lymph nodes are there

A

A few hundred

78
Q

What part of the lymph-node receives lymph

What else is here

A

The sub calculus sinus received lymph from afferent lymphatic vessels

Macrophages

79
Q

What is below the subcapsular sinus of the lymph nodes

A

The cortex and medulla, dense cellular areas of lymphocyte residence

80
Q

What is the function of the spleen

A

Remove old red blood cells and filter blood-borne antigens

Also serves as the location for initiation of immune response to blood pathogens

81
Q

Why is the spleen highly vascularised

A

To enable good blood filtration

82
Q

Does the spleen have a capsule

A

Yes but it is weak

83
Q

What is below the capsule of the spleen

A

A red blood cell rich area called the red pulp where and blood antigens are filtered and red blood cells removed

There is also a white blood cell rich area called the white pulp, where lymphocytes initiate immune responses to blood pathogens

84
Q

How many lymphocyte clones can react with a specific antigen of the invading pathogen

How is this overcome

A

1 in 10^6

Recirculation of lymphocytes

85
Q

Describe recirculation of lymphocytes

A

Naive lymphocytes transit through the blood, lymph-node‘s, spleen and return to the blood via the thoracic duct

Lymphocytes into limp nodes through venules called HEVs

Inside the lymph-node different lymphocytes concentrate in different areas: B cells home to follicles in the cortex, T cells home to the paracortex.
In these areas they can recognise and bind antigens brought by the lymph

86
Q

How do lymphocytes encounter antigens

A

Antigen presenting cells angles microbes and then actively migrate to the nearest lymph-node

87
Q

3 ways neutrophils kill bacteria

A

Phagocytosis

Production of cytokines and Antimicrobial enzymes

88
Q

How do neutrophils move

A

Amoeboid fashion

89
Q

Give 4 facts about nitric oxide

A

It generated by sheer stress on the endothelium of certain blood vessels

May up regulate factors involved in development of new vessels

Produced from L arginine

Vasodilator

HOM (11 decks)

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