Chapter 14 Cardiac Output, Blood Flow and Blood Pressure Flashcards
SA norde rhythmically excited at how many bpm
100bpm
pacemaker potential
What 2 ways does the Parasympathetic nervous system control on heart rate…
Resting state 70-75 bpm
ACh release from Parasympathetic nervous system causes heart rate lower than 100bpm
In addition to this, increase permeability to K results in slower rate of depolarisation
What 3 ways does the Sympathetic nervous system control on heart rate
- NE from sympathetic nervous system and E from adrenal medulla bind to Beta-Adrenergic receptors in SA node to increase heart rate
- Increase permeability of HCN channels = faster rate of depolarisation = increase heart rate
- Increase contractility and faster contraction and relaxation
How is the SA node effected by autonomic nerve activity
- Sympathetic: Increased rate of diastolic depolarisation = Increase cardiac rate
- Parasympathetic: Decrease rate of diastolic depolarisation = decreased cardiac rate
How is the AV node effected by autonomic nerve activity
- Sympathetic: Increased conduction rate
2. Parasympathetic: Decreased conduction rate
How is the Atrial muscle effected by autonomic nerve activity
Sympathetic: Increased strength of contraction
How is the Ventricular muscle effected by autonomic nerve activity
Sympathetic: Increased strength of contraction
What happens if EDV (Preload) increases
Greater Stroke volume
Because Frank-Starling law of heart
What is resistance
Impedance to blood flow
What happens if total peripheral resistance (afterload) increases
Greater pressure in the arterial system
Increased afterload
Lower Stroke volume
What happens when there is a greater arterial pressure
Increased after load
Therefore, heart must work harder to eject blood
What are the 3 ways stroke volume is regulated
- EDV
- TPR
- Contractility
How does contractility regulate stroke volume
Sympathetic system and adrenal medulla release E and NE to increase ventricular contractility = increase stroke volume
What is Frank-Starling law of the heart
As EDV increases so does stroke volume
At rest is the cardiac muscle length short or long
Short
With a greater EDV there is greater…
stretch = cardiac muscle length
What does a greater muscle length result in
Because
Increases strength of contraction
Because there is:
- Optimal alignment of actin and myosin
- Increased release of Ca from SR
EDV is effected by…
venous return
What does an increase in peripheral resistance do to Frank-Starling law
- Increase peripheral resistance decreases SV
- More blood remains in ventricle = increases EDV
- Increase stretch
- Stronger contraction to eject blood
Cardiac output =
Cardiac rate x stroke volume
What 3 main ways can you increase stroke volume
Increase:
EDV
NE delivery
E delivery
(Decrease):
Peripheral resistance
What 3 main ways can you increase heart rate
Increase:
NE delivery
E delivery
Decrease:
Parasympathetic
Sympathetically mediated venoconstriction can increase what
venous return to the RIGHT side of the heart
Extracellular fluid represents how much of the total bodies water
How much of that is made up of blood and ISF
1/3 of total body
This 1/3 is made up of 20% blood and 80% ISF
What pressure causes fluid to filter out of vessels into the ISF
Blood pressure
What pressure causes water to be absorbed from tissues to vessels
Osmotic pressure
Blood volume is regulated by… (3)
- Drinking
- Urine volume
- Distribution of water between plasma and ISF
How do the kidneys play a role in blood volume
- Urine is derived from blood plasma
2. ADH and Aldosterone act on kidneys to regulate blood volume
How is water lost by the body (4)
- Excretion of urine
- Exhalation of air
- Sweating
- Faeces
What is filtration
movement of fluid and solutes OUT of the blood
What is absorption
movement of fluid and solutes INTO the blood
What pressure causes filtration of fluid out of capillaries
Hydrostatic pressure
What is the hydrostatic pressure at the:
Arteriolar end
Venular end
of systemic capillaries
Arteriolar = 37 mm Hg Venular = 17 mm Hg
Why is ISF hydrostatic pressure low
Due to drainage into lymphatic vessels
What substances are filtered with the fluid
Solutes such as glucose, salts, ions