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Miscellaneous Flashcards

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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
Give 4 key functions of the blood
Transport of nutrients, gases, hormones, waste Restriction of fluid loss during injury Defence from infection Homoeostasis
26
What is hemostasis
Restriction of fluid loss
27
What are the 2 routes of transport across the capillary endothelial cell layer
Para cellular | Trans cellular
28
Describe the paracellular route of transport through capillary endothelium
Water and small solutes pass through the paracellular which this transport mode is limited by tight junctions and gap Junctions
29
Describe the transcellular route through endothelium
Larger sockets pass through this route either via a) receptor-mediated endocytosis or B) Trancytosis C) trans-endothelial channels such as vesicular vacuolar organelles
30
What are VVOs
Interconnected vesicles forming channels across the cell
31
Describe transcytosis
When cells take up extra cellular medium through caveolae-mediated macro pinocytosis and transfer to the opposite side of the cell
32
Where is fenestrated endothelium found
GI tract Glomerulus Endocrine cells
33
Describe the endothelium of the liver
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
34
Describe continuous nonfenestrated endothelium
Water and small solutes pass in between cells where as larger solutes pass through the cells via trans-cytosis
35
Where is the permeability of endothelium especially restricted
Brain
36
What forms the blood brain barrier (3)
Tighter endothelial junctions Thicker basement membrane A layer of supporting astrocytes
37
What does the BBB allow through (5)
``` Water Gases Lipid soluble hormones Glucose Some αα ```
38
How does the BBB prevent the entry of lipophilic potential neurotoxins
An active transport mechanism mediated by P – glycoprotein
39
Why are brain pathogens hard to treat
Antibodies are too large to cross the blood brain barrier and only certain antibiotics are able to pass
40
How do endothelial cells facilitate inflammation
Increase permeability so that plasma proteins and neutrophils can exit and reach the tissue/site of infection.
41
Do you fish and reptiles have enucleated RBCs
No
42
What could the loss of the nucleus in Mammalian red blood cells be related to
A larger genome in relation to body size and smaller diameter of capillaries
43
What does a pulse oximeter do
Measures blood oxygenation by comparing the different absorption of oxy Hb and deoxy Hb
44
Where does erythropoiesis occur in a) adults b) foetus
a) bone marrow | b) liver and spleen
45
How do RBC progenitor cells differentiate How are old RBCs destroyed
They progressively differentiate into red blood cells losing the nucleus, ribosomes and organelles By macrophages in the liver or spleen
46
Discuss EPO (3)
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
What is the hypoxia response regulated by
Hif α | hypoxia inducing factor
48
What happens to Hif α in normoxia What happens in hypoxia
Hydroxylated, leading to degradation The activity of hydroxylases is reduced and HIF α can activate transcription of EPO
49
Why is destruction of RBCs important
Damaged RBCs release haemoglobin and iron which are sequestered in the kidney causing inflammation and damage
50
Name the 3 granulocytes
Neutrophils Eosinophils Basophils
51
Name the 4 agranulocytes I
T lymphocytes B lymphocytes Monocytes Megakaryocytes
52
Discuss neutrophils (3)
Granules are visible with neutral dies Crucial for a bacterial infections Most abundant cells in the blood
53
discuss eosinophils
Granules are visible with acidic days Play a role in parasitic infections Granules contain peroxides and enzymes toxic to parasites
54
Discuss basophils
Granules are visible with basic ties Produce histamine and heparin Play a role in allergy
55
What do a) T and b) B lymphocytes do
a) kill infected cells or produce signals that assist function of other immune cells b) produce antibodies
56
What are natural killer cells
They kill ourselves through different mechanisms, important for antitumour responses
57
What do monocytes do
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
What can monocytes differentiate into
Macrophages and dendritic cells
59
What are megakaryocytes
They are large multinucleated cells whose segmentation gives rise to platelets Important for haemostasis
60
What happens after a vessel is injured
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
What is a vessel spasm
A decrease in diameter of vessel by muscle contraction
62
What factors are released from platelets (3) What do they do
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
What happens to the fibrinous mesh once the vessel wound is healed
Fibrinolysis follows Plasminogen has to be converted into plasmin, which breaks down fibrin Bradykinin relaxes the muscles and restores bloodflow
64
Give 4 functions of the lymphatic system
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
Is the lymphatic system a closed circulation
No it is 1 way
66
Which is higher: hydrostatic or osmotic capillary pressure Which are more permeable: lymphatic or blood vessels
Hydrostatic Lymphatic
67
3 things that facilitate lymph flow
Breathing Exercise Good posture
68
Where does the thoracic duct enter into
Subclavian vein
69
What is elefantiasis
Parasitic infection (helminth) of the lymphatic system Causes oedema
70
3 cells present in lymph
Lymphocytes Macrophages Dendritic cells
71
Where are B and T cells produced
``` B= bone marrow T= thymus ```
72
What do macrophages and dendritic cells do
Macrophages: clear dead cells | Dendritic cells: activate T cells
73
What are the secondary lymphoid organs
Lymph nodes Spleen Gut lymphoid
74
How many blood cells are produced a day
500 billion
75
Why does haematopoiesis decrease with age
Replacement of haematopoietic tissue with fat It decreases faster in Lower limbs
76
What colour is fat
Yellow
77
How many lymph nodes are there
A few hundred
78
What part of the lymph-node receives lymph What else is here
The sub calculus sinus received lymph from afferent lymphatic vessels Macrophages
79
What is below the subcapsular sinus of the lymph nodes
The cortex and medulla, dense cellular areas of lymphocyte residence
80
What is the function of the spleen
Remove old red blood cells and filter blood-borne antigens Also serves as the location for initiation of immune response to blood pathogens
81
Why is the spleen highly vascularised
To enable good blood filtration
82
Does the spleen have a capsule
Yes but it is weak
83
What is below the capsule of the spleen
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
How many lymphocyte clones can react with a specific antigen of the invading pathogen How is this overcome
1 in 10^6 Recirculation of lymphocytes
85
Describe recirculation of lymphocytes
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
How do lymphocytes encounter antigens
Antigen presenting cells angles microbes and then actively migrate to the nearest lymph-node
87
3 ways neutrophils kill bacteria
Phagocytosis | Production of cytokines and Antimicrobial enzymes
88
How do neutrophils move
Amoeboid fashion
89
Give 4 facts about nitric oxide
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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