Interactions of Organisms and their Environment Flashcards
What three factors affect blood pressure?
Cardiac Output
Peripheral resistance
Blood volume
What is the formula used to calculate blood pressure
BP=COxPR
Maintaining blood pressure requires what two things?
Cooperation of the heart, blood vessels and kidneys.
Supervision of the brain
Cardiac out put is determined by……….and ……an………… controls
venous return
neural
hormonal
Resting heart rate is controlled by the…………. via the ………
cardio-inhibitory centre
vagus nerves
Stroke volume is controlled by …….. return (end diastollic volume EDV)
venous
Under stress what does the cardioinhibitory centre do?
increase stroke volume and heart rate
End systolic volume (ESV) increases and MAP increases
Where are Conducting (elastic) arteries found?
near the heart and its major branches
What are the key characteristics of conducting arteries?
- Large lumen allow low resistance conduction of blood
- Contain elastin in all three tunics
- Withstand and smooth out large blood pressure fluctuations
- Allow blood to flow fairly continuously through the body
Where are distributing (muscular) found
distal to conducting arteries
What are the key characteristics of distributing arteries?
- Have thick tunica media with more smooth muscle and less elastic tissue
- Active in vasoconstriction
Where are pericytes found and what is their function?
Outer surface of capillary wall
To stabalise
What are the three types of capillaries?
continuous, fenestrated and sinusoids
What are the key structural characteristics of veins?
• Composed of three tunics, with a thin tunica media and a thick tunica exerna consisting of collagen fibres and elastic networks
What vessels are Capacitance vessels and what is their function?
Veins
Blood reservoirs
