1.2 Cardiovascular and respiratory systems 2 Flashcards
What is an autonomic nervous system (ANS)
the part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes.
involuntarily regulates heart rate and determines firing rate of the SA node
-higher firing rate of the SA node higher heart rate
What is the cardiac control centre
control centre in the medulla oblongata that controls the heart rate
Name the 3 main control mechanisms that determine the action of the cardiac control centre
-neural control
-intrinsic control
-hormonal control
What is neural control
chemoreceptors ->detect ^ in acidity in blood
proprioceptors -> detect movement in tendons & muscle fibres
baroreceptors -> detect increase in pressure in blood vessels
What is intrinsic control
temperature changes affect viscosity (thickness) of blood and speed of nerve impulse transmission
venous return changes affect stretch in ventricle walls, force of ventricular contraction, stroke volume
What is hormonal control
adrenaline and noradrenaline- released from adrenal glands-
increase force of ventricular contraction (therefore SV) - increasing spread of electrical activity through heart
What is the vascular system
network of blood vessels and blood
-ensures oxygen and nutrients are delivered to all respiring cells for energy production
- waste is removed efficiently
Name 3 functions of the blood
- transports oxygen and glucose
- protect and fight disease
- maintain the internal stability of the body
What are the three types of blood vessels
- arteries
- veins
- capillaries
What do arteries and arterioles do
transport oxygenated blood from the heart to muscles and organs
Name the main artery and what it does
aorta
-carries blood at a high pressure directly from left ventricle
-subdivides arterioles slowing blood flow
Name 3 characteristics of arteries
- large layer of smooth muscle
- elastic tissue to cushion and smooth blood
- small lumen
Explain what arterioles are
Small branch of an artery leading into capillaries
What are pre capillary sphincters
- ring of smooth muscle surrounding the entry of capillary bed.
- they dilate and constrict to control blood flow through capillary bed
What process occurs in capillaries
gas exchange
-O2 passes through capillary wall & into tissues
-CO2 passes from tissues -> blood through capillary wall
Explain characteristics of capillaries
- walls have a single layer, thin enough to allow gas, nutrient and waste exchange
What do veins and venules do
they transport deoxygenated blood from the muscles and organs back to the heart.
What is vasodilation
the widening of the arteries, arterioles and pre-capillary sphincters
What is vasoconstriction
narrowing of arteries, arterioles and pre-capillary sphincters
What is the main vein
vena cava
Name the characteristics of veins and venules
- small layer of smooth muscle allowing them to venodilate and venoconstrict to maintain the slow flow of blood towards the heart
-veins have one-way pocket valves which prevent backflow of blood
What is venous return
return of blood to the heart through the venules and veins back to the right atrium, largely against gravity
Why is a greater venous return needed during exercise
greater demand for oxygen -> more oxygenated blood requires greater venous return-> so stroke volume, cardiac output can increase.
What are the five mechanisms that aid venous return
- pocket valves
- smooth muscle
- gravity
- muscle pump
- respiratory pump
