Lecture #7 Flashcards
Flow is governed by two main variables, what are they?
- Pressure
- impels fluid to move
- According to pressure gradient (high to low) - Resistance
- opposes flow
Auscultation
Listening to sounds made by the body
S1 Lub
AV valves
S2 (Dub)
SL Valves
Pulmonary Edema
- Right Ventricle output exceeds left ventricle output
- Pressure backs up
- Fluid accumulates in pulmonary tissue
Systemic Edema
- Left Ventricle output exceeds right ventricle output
- Pressure backs up
- Fluid accumulates in systemic tissue
Cardiac Output
CO=HR(SV)
Volume of blood pumped per unit time
Cardiac Output can be modified by either term:
- Heart Rate (HR)
- Modulated by nervous and endocrine system
- bradycardia (<60bpm)
- Tachycardia (>100bpm) - Stroke Volume (SV)
- volume of blood pumped with each beat
- preload, contractility, and after load
Heart rate is regulated by?
Cardiac centers in the Medulla of the brain
1. Proprioceptors are responsible for activating muscles and joints
- Baroreceptors (pressure receptors)
are responsible for detecting changes in blood pressure, include the aorta and internal carotid arteries - Chemoreceptors are responsible for detecting blood pH, CO2, and O2, in Aortic arch, carotid arteries, medulla
Autonomic Nervous systtem
- influence the rate of impulse generation (firing), depolarization/depolarization of myocardium
- Influence strength of atrial and ventricular contraction
- influence changes in the heart and circulatory system faster than metabolic or humoral agents
Vagal Tone
Parasympathetic, slower heart rate between 70-80bpm
- if all sympathetic and parasympathetic stimulations or nerves are damage heart will continue beating at 100bpm
Blood Flow
- the amount of blood flowing through an organ, tissue, or blood vessel in a given time (mL/min)
Perfusion
the passage of fluid per given volume or mass of tissue in a given time (mL/min/g)
Flow of blood thought the body
- is constant and is equal to the cardiac output (5.25L/min)
- flow through individual organs varies from minute to minute
Hemodynamics
Physical principles of blood flow based on pressure and resistance
- the greater the difference between two points, the greater the flow
- the greater the resistance = less flow
Blood Pressure
is the force that blood exerts against a vessel wall
BP declines with distance from the heart
- arterial elasticity
- friction on vessel wall
Where is Blood Pressure measured?
Normal Value
brachial artery of the arm using sphymomanometer
= 120/75mmHg
Two pressures are recorded
- Systolic Pressure - peak arterial BP taken during ventricular contraction
- Diastolic Pressure - minimum arterial BP taken during ventricular relaxation (diastole)
Pulse Pressure
difference between systolic-diastolic pressure
Mean Arterial Pressure (MAP)
- the mean pressure, takes measurements at several intervals throughout the cardiac cycle
MAP = diastolic pressure + 1/3 (Pulse Pressure)
What is Atherosclerosis?
Fat build up inside the arteries (plaque)
- progressive conditions lead to coronary artery disease and peripheral artery disease
Define Hypertension
High blood pressure
BP>140/90
- can weaken arteries, cause aneurysms, promote atherosclerosis
Define Hypotension
chronic low resting BP
- caused by blood loss, dehydration and anemia
What are the factors contribute to blood pressure
- Cardiac Output - the amount of blood pumped out by the heart per minute
- Blood Volume
- regulated by the kidneys - Resistance to Flow
Peripheral Resistance
the opposition to flow that blood encounters in vessels away from the heart
What are the factors that influence resistance?
- Blood Viscosity (Thickness)
- increased mainly from RBC count and albumin - Vessel length
- more friction it encounters the father it goes
- pressure and flow declines with distance - Vessel Radius
- most powerful influence over flow
Laminar Flow
flows in layers, faster in the center.
small changes in blood vessel radius can cause large change in flow
Vasoconstriction
when smooth muscle of tunica media contracts
Vasodilation
relaxation of the smooth muscle, allowing blood pressure to expand vessel
Peripheral Resistance
Aorta to capillaries
Blood velocity decreases from aorta –> capillaries because:
- increase distance = more friction – lower speed
- decreased radii of vessels = more resistance
- Greater corss-sectional area because the # of vessel increase
Peripheral Resistance From capillaries – > vena cava velocity increase because:
- Veins are larger = less resistance than capillaries
- Convergence of vessels large amounts of blood into smaller channels
BLOOD IN VEINS NEVER REGAIN VELOCITY IT LOST
Vasoreflexes
are quick and powerful ways of regulating blood pressure and flow
Two purposes of dilation and constriction are?
- General control of BP throughout the whole body
2. Method of rerouting blood from one region to another for perfusion of individual organs
What are the 3 ways of controlling vasomotor activity?
- Local Control
- Neural Control
- Hormonal Control
