Physiology Flashcards
1
Q
How much of total body weight does blood make up?
A
About 8%
2
Q
How many litres of blood do female adults have?
A
5
3
Q
How many litres of blood do male adults have?
A
5.5
4
Q
How much blood is in the lungs?
A
0.6 litres
5
Q
How much blood is in systemic venous circulation?
A
3 litres
6
Q
How much blood is in the heart, systemic arteries, arterioles and capillaries?
A
1.4 litres
7
Q
Functions of blood
A
-Gas transport and exchange
-Distributing solutes
-Immune functions
-Maintains body temperature
-Regulates blood clotting
-Preserving acid-base homeostasis
-Stabilising blood pressure
8
Q
What pH is blood maintained between?
A
7.35-7.45
9
Q
What is transported in plasma?
A
Ions, nutrients, hormones, metabolic waste
10
Q
What are erythrocytes?
A
Red blood cells
11
Q
What are leukocytes?
A
White blood cells
12
Q
What are thrombocytes?
A
Platelets
13
Q
What is haematocrit?
A
Percentage of total blood volume occupied by red blood cells
14
Q
How much of the blood does plasma make up?
A
55%
15
Q
How much of the blood do white blood cells and platelets make up?
A
1%
16
Q
How much of the blood does haematocrit make up?
A
44%
17
Q
What is the normal naematocrit of a female?
A
42% (36.1%-44.3%)
18
Q
What is the normal naematocrit of a male?
A
45% (40-7%-50.3%)
19
Q
5 types of white blood cells
A
Lymphocytes, monocytes, neutrophils, eosinophils, basophils
20
Q
Two main functions of plasma
A
Thermoregulation and transport
21
Q
Components of plasma
A
Water, plasma proteins, dissolved small molecules
22
Q
How much of plasma is water?
A
> 90%
23
Q
How much of plasma do plasma proteins make up?
A
8%
24
Q
What are the plasma proteins?
A
Serum albumin, globulins, clotting proteins
25
How much of plasma protein is serum albumin?
55%
26
Function of serum albumin
- Maintains osmotic pressure of plasma
- Assists in transport of lipids and steroid hormones
27
Where is serum albumin synthesised?
Liver
28
How much of plasma proteins are globulins?
38%
29
Function of globulins
- Bind to and transport ions, hormones and lipids otherwise incompatible with water-based plasma
- Immune proteins: antibodies or gammaglobulins, made by leukocytes
30
How much of plasma proteins are clotting proteins (fibrinogen)?
7%
31
Function of clotting proteins (fibrinogen)?
Essential for blood clotting
32
Where are clotting proteins (fibrinogen) synthesised?
Liver
33
How much of plasma do dissolved small molecules make up?
1-2%
34
What are dissolved small molecules
in plasma?
Nutrients, waste produces, dissolved gases, hormones, vitamins, minerals
35
What structure are red blood cells?
Biconcave
36
Explain the function of the shape of red blood cells
Contributes to the efficiency of oxygen transport in the blood
37
Primary function of red blood cells
Oxygen transport
38
How much haemoglobin(%) in a red blood cell?
35%
39
How many mitochondria in area blood cell?
0 - can't use transported oxygen
40
What is the volume of erythrocytes?
80-96 femtolitres
41
What is MCV?
Mean cell volume
42
What are microcytic red blood cells and where are they found?
Small - found in iron deficiency anaemia
43
What are macrocyctic red blood cells and where are they found?
Large - found in folate (vitamin B9) deficiency anaemia
44
Where for synthesis of blood cells start?
Bone marrow
45
What is erythropoiesis?
Red blood cell formation
46
How long does erythrocyte synthesis take?
About 26 days
47
Where is erythrocyte synthesis started and completed?
Starts in bone marrow, completed in blood vessels
48
How much oxygen in blood is bound to haemoglobin?
98.5%
49
What is haemoglobin made up of?
1. Globin - made up of four protein chains
2. Four iron containing haem groups
50
How many oxygen passengers can a haemoglobin molecule carry?
4
51
What is haem?
Iron containing pigment, consists of a porphyrin ring containing one atom of iron
52
What forms of globin proteins exist?
Alpha, beta, gamma, delta
53
What is HbA?
2 alphas and two betas
54
What percentage of adults have HbA?
97%
55
What is HbA2?
Two alphas and two deltas
56
What percentage of adults have HbA2?
2.5%
57
What is HbF?
Two alphas and two gammas, foetal HB
58
What is oxygen binding to Hb governed by?
-Partial pressure of oxygen
-Number of free oxygen binding sites available
O2 binding is cooperative
59
What are the 2 forms of Hb?
Taut (t) and relaxed (r)
60
What is the r form of Hb?
Relaxed - high O2 affinity, exists at high PO2, firmly binds oxygen (e.g. in the lings)
61
What is the t form of Hb?
Taut - low O2 affinity, exists at low PO2, releases oxygen (in peripheral tissues)
62
What can Hb bind to other than oxygen?
Carbon dioxide, carbon monoxide, nitric oxide, the acidic hydrogen ion portion of carbonic acid
63
Name 2 types of major classes of inherited disorders that cause abnormalities in Hb production
Haemoglobinpathies and the Thalassaemias
64
What are haemoglobinpathies?
Abnormal globin chains are made - sickle cell anaemia
65
What are the Thalassaemmias?
Normal globin chains are made but in decreased amounts OR are absent because of defects at the level of gene expression
66
What is sickle cell anaemia?
-Genetic disease
-Mutation in the B-globin gene
-A glutamic acid residue is replaced by valine
-Creates 'sticky patches' on the molecule
-Resultant haemoglobin (HbS) polymerises at low pO2 forming long crystals of HbS
-Red blood cells deform and become sickle shaped
67
What is a Thalassaemia?
-Found predominantly in India
-Production of a globins is reduced
-Leads to excess B chains
-Leads to abnormal oxygen dissociation curves and RBC damage
-Short lived RBC -> anaemia
68
What is B thalassaemia?
-Predominantly in Mediterranean region
-Relative excess of a chains
-Do not form tetramers
-Bind to and damage RBC membranes
-At high concentrations form toxic aggregates
-RBC are fragile and short lived -> anaemia
69
What is HBH?
4 beta chains
70
What is haemostasis?
The arrest of bleeding from a broken blood vessel
70
How do the body's haemostatic mechanisms normally stop loss of blood?
Through small damaged capillaries, arterioles and venules
71
What are platelets?
Not whole cells but small cell fragments that have budded off megakaryocytes
72
What are megakaryocytes?
Extraordinarily large bone marrow
73
What regulates megakaryocyte and platelet production?
Thrombopoietin
74
Where is thrombopoietin produced?
Liver and kidneys
75
What is thrombopoiesis?
Platelet synthesis
76
Describe platelet synthesis
-Hematopoletic stem cells differentiate into megakaryoblasts
-Megakaryoblasts develop into megakaryocytes
-Megakaryocytes are massive cells with multiple copies of DNA
-Thrombopoietin stimulates megakaryocytes to extend arms through bone marrow sinusoids into blood vessels
-Break off as platelets
77
Where are platelets stored?
The spleen
78
How are platelets released
Contraction of the spleen
79
How are platelets activated?
By the sympathetic nervous system
80
3 steps of homeostasis
1. Vascular spasm
2. Formation of platelet plug
3. Blood coagulation
Platelets have a role in all 3 steps
81
What is vascular spasm?
-Cut or tear in blood vessel -> damaged cells and platelets at cut site release potent vasoconstrictors such as serotonin and ADP
-As the ends of the endothelial surfaces are pushed together by the spasm they become sticky and adhere to each other. Aided by platelets sticking to exposed collagen
82
What is platelet plug formation?
-Adhesion - platelets stick to each other using von Willebrand's factor, a plasma protein secreted by endothelial cells and platelets
-Activation
-Aggregation - the plug seals the break in the vessel lining and performs three other functinos
83
What functions does the platelet plug perform?
1. Compaction/strengthening
2. Further vasoconstriction
3. Stimulation of the clotting cascade
84
What is prostacyclin?
-Released by normal blood vessel lining
-Inhibits platelet aggregation
-Limits platelet plug to the damaged region of the vessel preventing its spread to normal, undamaged tissue
85
What is blood coagulation?
-Blood clotting
-Process changing liquid blood to a solid gel
-Clot strengthens and supports the platelet plug
86
What is the final step in clot formation?
Conversion of fibrinogen into fibrin. Red blood cells are enmeshed in the fibrin plug
87
Which pathways can stimulate thrombin activity?
Intrinsic pathway and extrinsic pathway
88
What is the intrinsic pathway?
Initial stimulus is exposed to collagen
89
What is the extrinsic pathway?
Initial stimulus is blood contact with damaged tissue outside of the blood vessel that exposes tissue factor (also known as factor 3 or tissue thromboplastin)
90
What is the normal blood clotting process?
1. Initiation phase - tissue exposure initially triggers the extrinsic pathway leading to thrombin production, but the amounts produced are too small for sustained coagulation
2. Amplification phase - thrombin produced by the extrinsic pathway feeds back and activates the intrinsic pathway
91
What is a blood group?
Classification of blood based on presence of inherited antigenic substances on surface of red blood cells
92
How many known human blood group systems are there?
43
93
What is a complete blood group?
The set of surface antigens on the individual's RBC
94
What is a blood group?
Usually only the ABO system and the presence or absence of the Rhesus D antigen
95
How may blood group change?
-Infection
-Malignancy
-Autoimmune disease
-Bone marrow transplant
96
Functions of the respiratory system
-Exchange of gases
-Regulation of body pH
-Protection from inhaled pathogens and irritants
-Vocalisation
97
What is ventilation?
Inhalation and expiration
98
What is external respiration?
Atmosphere to lung, lung to blood
99
What is internal transport?
Transport of gases into the blood
100
What is internal respiration?
Blood to cells
101
How many lobes do the left and right lungs have?
Right -3
Left - 2, includes cardiac notch
102
What comprises the upper respiratory tract?
Nasal cavity, pharynx, larynx
103
What comprises the lower respiratory tract?
Trachea, bronchi, bronchioles
104
What is the respiratory zone?
Comprised of alveoli and capillary supply
105
The bronchial tree
-2 primary bronchi
-5 secondary bronchi (2 left, 3 right)
-18 tertiary bronchi (8 left, 10 right)
-Continue to divide (up to 11 divisions)
-Bronchioles
-Cluster of alveoli
106
What one goblet cells?
Secrete mucus to form continuous mucus layer over surface of respiratory tract
107
What are ciliated cells?
Produce saline, sweep mucus upwards to pharynx
108
What is the mucociliary escalator?
Removes noxious particles from lungs
109
What is saline secretion essential for?
Functional mucociliary escalator
110
Histology of the lower conducting system - larynx, trachea and primary bronchi
-Lined by ciliated respiratory epithelial cell layer
-Supported by c-shaped cartilage rings - to keep trachea open (patent);flexible enough to allow trachea to change in diameter during pulmonary ventilation
-Posterior surface of trachea is covered with elastic connective tissue and smooth muscle (trachealis); allows oesophagus to expand during swallowing
111
Histology of the lower conducting system - larynx, trachea and primary bronchi bronchi to bronchioles
-Cartilage changes to complete rings, to progressively fewer, irregular, plates
-Epithelium gradually changes to columnar cells in smaller bronchi
-Amount of smooth muscle increases
112
Vasculature
-Extensive capillary network provides large surface area for gas exchange
-Pulmonary artery supplies deoxygenated blood
-Pulmonary vein carries oxygenated blood
113
Alveolar structure
Type I alveolar cell: ~90% of alveolar cells, very thin; gas exchange
Type II alveolar cell: smaller, thicker; produce surfactant (L15)
Macrophages: protect alveolar structures from non-filtered, small particles
114
What is Boyle's law?
At constant temp and no. of particles, pressure and volume of a gas and inversely proportional
115
What is the process of pulmonary ventilation?
-Involves volume changes in thoracic cavity and lungs that lead to creation of pressure gradient
-Gradient causes air to move into or out of lungs
116
What pressure gradients influence ventilation?
Atmospheric pressure, intrapulmonary pressure, intrapleural pressure
117
What is intrapulmonary pressure?
-Air pressure within alveoli
-Rises and falls with inspiration and expiration
-Always eventually equalises with atmospheric pressure due to pressure gradients reaching equilibrium
118
What is intrapleural pressure?
-Pressure found within pleural cavity
-Rises and falls with inspiration and expiration
-Does not equalise with atmospheric pressure - normally ~4 mmHg less than intrapulmonary pressure
