Cardiovascular definitions Flashcards
1
Q
Define Stroke Volume
A
- Amount of blood pumped by L ventricle in one contraction during systole in mL
- Affected by heart rate, force of contraction and preload
- End diastolic volume - End systolic volume
- End diastolic = amount left in L ventricle after diastole
- End systolic = amount left in L ventricle after systole
- Stroke volume is relevant to cardiac output and is important in maintaining blood circulation
2
Q
Define cardiac output
A
- Volume of blood pumped by L ventricle in 1 minute in L/min or mL/min
- Assessment of whether a blood supply is enough to meet metabolic demand
- Heart rate x Stroke volume
- Heart rate = beats per minute
- Stroke volume = volume ejected from L ventricle with each contraction
- Used for assessing cardiac health, diagnosing conditions, and observations of patients
3
Q
Define Bicuspid Valve
A
- 1 of 4 main cardiac valves located between the left atrium and left ventricle
- Called bicuspid due to 2 cusps
- Ensures one way blood flow from L atrium to L ventricle
- Allows the contracting ventricle to force blood into the aorta not back into the atrium
4
Q
Define Cardiac Muscle
A
- Specialised muscle cells (myocardium) of the heart
- Acts to involuntarily contract the heart creating a rhythmic beat to circulate blood
- Cardiac muscle is striated, branched cells form a network, highly resistant to fatigue
- Cardiac muscle needs a constant supply of O2 and nutrients to maintain function
5
Q
Define Sinoatrial Node
A
- Natural pacemaker of heart, cluster of cells in R atrium
- Generates electrics impulses to initiate a heartbeat and set the rhythm for the heart
- Sets coordinated contractions at a rate determined by physiological needs
- The impulses cause atrial contraction and then ventricular contractions allowing blood distribution
- The rate at which the SA node generates signals is determined by the autonomic system, hormones and external stimuli
6
Q
Define Sympathetic Nervous System
A
- A branch of the autonomic nervous system, which is responsible for regulating involuntary bodily functions relating to fight or flight
- The sympathetic nervous system is responsible for the bodily responses to stress, danger, or physically demanding situations
- Some features include increased alertness, increased HR, increase physical readiness, dilated pupils, tachycardia, increased sweating, mobilisation of energy
- Acts in opposition to the parasympathetic nervous system, crucial to maintain homeostasis
7
Q
Define Conducting System or the Heart
A
- Group of cells responsible for ensuring the heart beats in a coordinated manner
- Includes the SA node, AV node (slows down signals allowing the ventricles time to fill), the bundle of his (conducts signals from the SA node), the Purkinje fibres (allows for coordinated contraction of the ventricles)
8
Q
Define End Diastolic Volume
A
- Volume of blood left in L ventricle at end of diastole
- Has a relation to stroke volume, cardiac output and overall efficiency of the heart
- Influenced by amount of blood returning to heart and hearts ability to fill during diastole
- Larger EDV = larger stroke volume, generally causing an increased HR
- Monitoring and understanding EDV helps us to diagnose and manage cardiac conditions
9
Q
Define Total Peripheral Resistance
A
- Resistance to blood flow - force of friction between blood and vessel walls
- Influenced by total vessel length, blood viscosity, blood vessel radius
- Multiplied by perfusion to calculate mean arterial pressure
10
Q
Define Venous Return
A
- Amount of blood returning to the heart
- More blood returning means that more blood is available to fill the ventricles and be redistributed out of the heart
- Influenced by:
Blood volume, gravity, muscle pump, joint pump, respiratory pump (pressure in abdomen increases as diaphragm contracts and descends during inspiration)
11
Q
Define Starlings Law
A
- The relationship between stroke volume and EDV
- SV increases the more ventricles are filled before contraction (preload)
- The more stretch is placed on heart fibres the more forceful the resulting contraction
12
Q
Define Cardiovascular Centre
A
- Part of the brain regulating HR and SV through nervous and endocrine systems
- Receives input from higher centres (cerebral cortex, limbic system and hypothalamus) and sensory rece[tors
- Found in medulla oblongata
- Responsible for cardiac output
- Uses both sympathetic and parasympathetic systems of the autonomic nervous system to send output to the heart
13
Q
Define Parasympathetic Nervous System
A
- Dominant system in ‘rest and digest’ conditions
- Main purpose is to conserve energy to be used later and regulate bodily functions like digestion and urination
- Key features include:
Decreased HR - bradycardia, bronchoconstriction, reduced BP
14
Q
Define Inotropes
A
- Types of medicines that change the force of the contraction in the heart
- Positive inotropes: strengthen the force of the heartbeat, given to those with congestive heart failure/ in ICU
- Negative inotropes: weaken the force of the heartbeat, given to those who want to keep their BP normal - not dealing with life-threatening situations
15
Q
Define Adrenaline
A
- Hormone and neurotransmitter produced by the body when a person is frightened or angry - linked to fight/ flight
- Release stimulated by sympathetic nerves
- Secreted from adrenal medulla, causes HR to increase and lungs to breathe more efficiently
- More blood is sent to the brain and muscles, less to the digestive system etc, increased blood sugar levels so more energy is readily available
