CVS: Anatomy and Physiology Flashcards
What is physiology?
The science which describes the function of cells, and the organisational and functional relationships between cells, tissue, organs, and body systems
What are homeostasis and allostasis?
Homeostasis is the body responding to feedback from the environment
Allostasis is the same as homeostasis BUT in anticipation of what should occur
What is associated with feedback and feedforwad?
The stimulation of sensors and receptors
Why is physiological variation important?
Looking at extremes in regards to genotype/phenotype, allowing a range to be used to consider what is normal
What is the significance of the “normal range” regarding physiology?
Any physiological variation that falls within the range is considered normal, and anything outside of the range is abnormal
What are some factors that can be included in physiological variation?
Heart size, haemoglobin, blood pressure, etc.
Are physiological norms constant?
No physiological norms change throughout life course (foetal, neonatal, childhood, adolescent, adulthood)
How can physiological norms change?
In response to the stimulus, e.g., continued exposure to stimulus like stress leads to an increased resting BP
What are other causes of physiological adaptations?
Healthy lifestyles and diseases
Which system does the cardiovascular system (CVS) work with?
Cardiorespiratory system (CRS)
However all bodily systems work together and are not isolated
What would happen if one bodily system was incorrectly functioning?
As all bodily systems work together, this would cause a domino effect therefore the other systems are also affected e.g., if there are respiratory problems CVS tries to compensate for oxygen loss
What is the physiological role of the CVS?
Electrical conduction of the heart
Distributes leukocytes (white blood cells) and so helps the immune system
Oxygen distribution
Nutrient distribution
Regulates temperature
Platelets are distributed, therefore allowing scabs to form (protect against pathogens entering from wounds)
Blood transport
Hormone transport
What are the components of the cardiovascular system?
Heart
Veins and venules (venous system)
Arteries and arterioles (arterial system)
Capillaries
What would the site of a venipuncture be and what would the blood composition be?
Vein (median cubital, cephalic or basilic vein)
Venous blood (deoxygenated blood)
What would the site of an arterial blood sample be and what would the blood composition be?
Artery (radial or femoral artery)
Arterial blood (oxygenated blood)
What would the site be for a finger-tip and what would the blood composition be?
Capillary (second and third finger)
Mixed venous-arterial blood
What would the site for a heel-prick be and what would the blood composition be?
Capillary (medial or lateral surface)
Mixed venous-arterial blood
When do arterioles and venules form?
Further from the heart; veins and arteries become smaller and divide into venules and arterioles
What is the main function of a capillary?
Sites of exchange e.g., oxygen diffusion
What is an example of a capillary bed function?
Capillary bed–> venules–> heart–>oxygen
What is the difference between arterial and venous blood?
Varying blood concentrations
What is the benefit of a finger-tip blood prick?
Can obtain the [blood glucose] from the capillary blood from the capillary blood
What is the importance of the heel-prick test for infants?
Allows for screening of diseases and conditions
Good supply of capillary beds
Where is the usual site of arterial blood taken?
Radial artery- the wrist
What are some key differences between the veins and arteries?
Arteries are more sensitive than veins
Arteries are smaller than veins (also have a smaller lumen)
What are the features of the heart?
Superior Vena Cava (deoxygenated blood to the right of the heart)
Pulmonary vein
Right Atrium
Tricuspid Valve (right atrioventricular valve)
Right Ventricle
Aorta
Pulmonary Artery
Left Atrium
Mitral Valve (left atrioventricular valve)
Left Ventricle
How can the left ventricle be differentiated form the right ventricle?
The left ventricle has thicker muscle walls
What is the myocardium and what are some of the key features?
Myocardium is a muscle layer of the heart
Thickest layer
Specialised muscle tissue
Composed of cardiomyocytes and intercalated discs
Striated
Involuntary movement
What is the endocardium?
Inner endothelial lining covering trabeculae
Comes after the myocardium
What is the serous pericardium?
Visceral layer
Epicardium
Comes before the myocardium and the endocardium
What is the pericardium composed of?
Fibrous pericardium
Serous pericardium (parietal layer)
Space between serous pericardium (parietal layer) and the serous pericardium (visceral layer)
What is pericarditis?
Inflammation of the pericardium
What occurs to the action potential during electrophysiology?
Action potential is initiated at the SA (Sino-atrial) node
(SA has a lower threshold potential difference than the rest of the rest of the heart)
Spreads across atria (right atrium first); atria contract therefore in atria systole (insulating layer of fat to delay conduction of the action potential, so the atria can completely empty)
Received at the AV (atrioventricular) node and conducted to base of the heart
Diverted down Bundle of His and travels down the septum
Travels along the bundle branches
Conducted by Purkinje fibres
Spreads across the ventricles, causes contraction of the heart from the apex upwards
Ventricular systole
What occurs in order for ventricular systole to occur?
Articular diastole
What are the peaks in an ECG called?
P wave
PR interval
QRS complex
ST segment
T wave
QT interval
(U wave)
What does an isoelectric line represent on an ECG?
Pointing down: away from node (negative)
Pointing up: towards node (positive)
What does the P wave represent on an ECG?
Atrial depolarisation (atrial systole)
Voltage (height of graph) and voltage direction (line)
What does the PR interval represent on an ECG?
Time between the onset of depolarisation in the atria and the onset of depolarisation in the ventricles
What does the QRS complex represent on an ECG?
Ventricular depolarisation
What does the ST segment represent on an ECG?
Plateau phase of ventricular depolarisation
What does the T wave represent on an ECG?
Ventricular repolarisation
What does the QT interval represent on an ECG?
Ventricular depolarisation and repolarisation
What does the U wave represent on an ECG?
Normal component of the surface ECG represents the delayed repolarisation of the Purkinje network, seen at the same time as early after depolarisation in patients with a prolonged QT interval and TdP
What are the physiological roles of blood?
Transport of: nutrients (e.g., CHO, FAT, PRO), gases (e.g., oxygen, carbon dioxide), heat (e.g., thermoregulation), water (e.g., hydration), etc.
Blood clots: forming blood clots (coagulation) to prevent excess blood loss during injury
Immunity: transporting cells and antibodies to prevent and fight infection (e.g., leukocytes)
What is the composition of blood?
Haematocrit (45%): erythrocytes (red blood cells)
Buffy coat (<1%): leukocytes (white blood cells) and platelets
Plasma (55%): water, proteins, other solutes (e.g., ions, gases)
What percentage of the total body weight does blood make?
8% blood
92% tissues and other fluids
What is the composition of the haematocrit, buffy coat and the plasma?
Haematocrit
Erythrocytes: >99%
Buffy Coat:
Platelets: <1%
Leukocytes: <1%
Plasma:
Proteins: 7%
Water: 91%
Other Solutes: 2%
What is the composition of proteins present in the plasma?
Albumins: 57%
Globulins: 38%
Fibrinogen: 4%
Prothrombin: 1%
What are the other solutes present in the plasma?
Ions
Nutrients
Waste Products
Gases
Regulatory substances
What is the composition of leukocytes in the buffy coat?
Neutrophils: 60%-70%
Lymphocytes: 20%-25%
Monocytes: 3%-8%
Eosinophils: 2%-4%
Basophils: 0.5%-1%
What is the normal blood haematocrit?
Females: 37%-47%
Males: 42%-52%
When is anaemia identified?
When the haematocrit <45% erythrocytes
When is polycythaemia identified?
When the haematocrit >45% erythrocytes
Where are erythrocytes produced?
In the bone marrow and are regulated by EPO (erythropoietin) hormone
What are some features of erythrocytes?
Biconcave shape
Large surface area
7.5 um in length
2.5 um in width
Each RBC contains haemoglobin (280 million Hb molecules)
What is the main feature of haemoglobin and why is it useful?
Each Hb molecule has 4 binding sites
4 x 280 million> 1 billion O2 molecules
Why is carbon monoxide a threat in regards to Hb?
Hb has a higher affinity for CO than O2, therefore, CO will associate more with Hb than O2 leading to oxygen deprivation
How can hypoxaemia trigger homeostasis?
Hypoxaemia: deteriorated [Oxygen] in blood as of insufficient oxygen transport (results in blotched skin)
Detected by liver and kidneys
Secretion of EPO
Stimulation of red bone marrow
Accelerated erythropoiesis
Increased RBC count
Increased oxygen transport
What is blood pressure?
The force of circulated blood on the walls of the arteries during contraction (systole) and relaxation (diastole)
What are the two main types of blood pressure and what are they at resting conditions?
Systolic blood pressure (SBP) and diastolic blood pressure (DBP)
Normotensive SBP <140 mmHg
Normotensive DBP <90 mmHg
What is the value of a normal pulse pressure and what is its formula?
40 mmHg
Systolic pressure - Diastolic pressure= pulse pressure
E.g., 120/80 mmHg–> 120-80= 40 mmHg
What is the trend in blood pressure across the circulatory system?
Blood leaves the heart at highest blood pressure at aorta after leaving Left Ventricle
BP decreases across elastic arteries, muscular arteries, arterioles, capillaries, venules, medium and large veins
BP lowest at vena cave before entering Right Atrium
Why does the BP decrease as blood leaves the left ventricle?
Blood pressure decreases as cross-sectional area and diameter increase, due to resistance decreasing
What is mean arterial pressure?
The average of the SBP and DBP
What is total peripheral resistance and what are the factors that affect it?
Blood cells and plasma encounter resistance as they travel through blood vessels. This resistance is due to contact with vessel walls.
Affected by: blood vessel diameter, blood viscosity and blood vessel length
What does high resistance mean?
More pressure is required to keep blood moving
What attributes to low/small peripheral resistance?
Low viscosity
Shorter vessel length
Larger vessel diameter
What attributes to high/large peripheral resistance?
High viscosity
Larger vessel length
Shorter vessel diameter
Why does a longer vessel length contribute to a higher peripheral resistance?
Longer length means more collisions, and so more resistance is generated
What are some physiological factors to note that affect total peripheral resistance?
- Cardiac output (CO=Heart Rate x Stroke Volume) (e.g. stress, physical activity)
- Volume of circulating blood (e.g. fluid intake, salt intake, blood glucose)
- Viscosity (thickness) of blood
- Elasticity of vessels walls (e.g. age, general health)
- Peripheral vascular resistance
- Other physiological factors
What are hypertension and hypotension?
Hypertension is an elevated blood pressure that helps with blockages
Hypotension is a decreased blood pressure
What is a common occurrence of both hyper- and hypotension?
Increased risk of heart disease, kidney damage and stroke (heart attack in the brain)
Similar structures are vulnerable to both hypertension and hypotension, although for different reasons
What are some lifestyle factors that can affect blood pressure?
Smoking
Physical activity
Alcohol consumption
Stress
Overweight and obesity
Caffeine consumption
Sleep disturbances
