6.2 blood system Flashcards
what does blood comprise of? fill in
- ???
- RBC
- WBC
- platelets
- ions
- ???
plasma, plasma proteins
the left side of the heart pumps [ox/deox] blood to ______
oxygenated, the body
the right side of the heart pumps [ox/deox] blood to _______
deoxygenated, lungs
which type of blood vessel transports blood at high pressure from the heart ventricles to body tissues and lungs?
arteries
what are the structural features of arteries? (4)
- narrow lumen
- maintain high b.p.
- thick wall w outer layer of collagen
- withstand high pressure needed to pump blood to e rest of e body
- inner layer of smooth muscle
- for contraction/dilation to alter diameter of lumen and thus control local b.p.
- elastic fibres
- allow artery walls to stretch + recoil
- maintains pressure + helps pump the blood
what are the structural features of capillaries? (3)
- 1-cell thick endothelium w permeable basement membrane only
- quick exchange of materials
- narrow
- penetrate all parts of tissues to deliver blood close to the cells
- large total cross-sectional area (of capillary bed)
- slow blood flow allows time for exchange
what are sinusodial capillaries?
capillaries w open spaces between cells
what are capillaries with pores called?
fenestrated capillaries
capillaries that limit permeability of large molecules are usually ___________capillaries
continuous
veins function to…
collect blood from the tissues and transport it at low pressure to the atria of the heart
what are the structural features of veins?
- very wide lumen
- maximise blood flow
- thin wall containing less muscle and elastic fibres
- as pressure is low
- valves
- prevent backflow of blood
why would backflow of blood occur in veins?
venous pressure it too low to readily pump blood back to the heart against gravity
what assists blood flow in veins? (short)
skeletal muscular activity
identify the blood vessels
-
what moves into tissues from the bloodstream?
- O2
- nutrients
- hormones
what moves out of the tissues from the bloodstream?
- CO2
- nitrogenous waste
- hormones
William Harvey discovered that…
the heart pumped blood around the body
what are the advantages of double circulation? (2 short)
- ensures ox and deox blood do not mix
- lower b.p. in pulmonary circuit to facilitate gaseous exchange at the lungs
- higher b.p. for systemic circuit to pump blood throughout body
label a diagram of a heart
-
label a dissected heart
-
the heart beat is initiated by the…
sinoatrial node
what is the sinoatrial (SA) node and its function?
a group of specialised muscle cells which generate electric impulses to control the rate and timing at which cardiac muscle cell contract
the SA node acts as a __________
pacemaker
how does the SA node control the heartbeat?
they spontaneously produce an electrical impulse
why is there a delay between the ‘lub’ and ‘dub’ heart sounds?
- SA node spontaneously produces an electrical impulse
- impulse is first propagated through the wall of the atrias, causing atria to contract
- AV node is stimulated by impulses and sends a signal across to the septum via Bundle of His and then Purkinje fibres
- causes ventricular contraction
- sequence of events allows delay between atrial and ventricular contraction
- thus delay between ‘lub’ and ‘dub’ heart sounds
why is a delay between atrial and ventricular contraction necessary?
to allow time for the ventricles to fill w blood
what is the basal heart rate?
the heart rate when a person is at rest
what determines the basal heart rate?
sinoatrial node
what is a trigger that can cause changes in heart rate?
changes to conc of CO2 (changes in blood pH)
the transmission of _________ and the release of _____ can cause changes in heart rate
nerves impulses, hormones
what does ‘autonomic’ in autonomic nervous system (ANS) mean?
involuntary
what are the two main pathways in the autonomic nervous system
parasympathetic and sympathetic
what is the part of the brain that sends nerve impulses to cause changes in the heart rate?
medulla oblongata
the two nerves that are help regulate the heart rate are…
parasympathetic nerve and sympathetic nerve
the parasympathetic and sympathetic nerves release… (1 word)
neurotransmitters
what neurotransmitter does the parasympathetic nerve release?
acetylcholine
the sympathetic nerves releases the neurotransmitter __________
noradrenaline
nerve impulses are sent down the _____________ pathway via the ________ nerve to cause a decrease in heart rate
parasympathetic, vagus nerve
what nerve does the sympathetic pathway use to send nerve impulses?
cardiac sympathetic nerve
parasympathetic and sympathetic pathways represent ______________ (relationship) control of the autonomic nervous system
antagonistic
recap: what are hormones?
chemical messengers released into the bloodstream that act specifically on distant target sites
what hormone is released to increase heart rate?
adrenaline
what is another name for adrenaline?
epinephrine
from where is adrenaline released?
from the adrenal glands
how does adrenaline affect the heart during fight-or-flight response? (1, short)
- incr heart rate by incr force of contraction in preparation for vigorous physical activity
what happens to the heart during a fight-or-flight response? (5)
- nerve response
- the medulla oblongata sends nerve impulses down the sympathetic pathway via cardiac sympathetic nerve
- nerve releases neurotransmitter noradrenaline
- causes SA node to speed up heart rate + incr force of contraction - hormone response
- adrenaline is released by adrenal glands
- causes SA node to incr heart rate- this incr the transport of O2 and glucose for vigorous physical activity
what does systole mean? hint: sustain
contraction
what does diastole mean? hint: dilate
relaxation
briefly name the events of the cardiac cycle
atrial systole -> ventricular systole/atrial diastole -> ventricular diastole
what happens during ventricular systole/atrial diastole? (6)
- ventricular systole:
- ventricles contract, incr b.p. within
- this forces AV valves to close -> prevent backflow of blood -> ‘lub’
- forces semilunar valves in pulmonary artery and aorta to open
- blood flows to the lungs + rest of e body respectively - atrial diastole:
- atria relax
- atria is refilled by ox and deox blood from pulmonary veins and vena cava respectively
what happens during ventricular diastole? (4)
- ventricles relax -> reduces pressure within
- semilunar valves close -> prevent backflow of blood into ventricles -> ‘dub’
- when pressure in ventricles drops to a lvl lower than atrial pressure, AV valves open
- blood passes passively into ventricles
what happens during atrial systole? (3)
- atria contracts
- remaining blood is pumped into ventricles
- ventricles filled w blood
what causes the ‘lub’ sound?
closing of AV valves
what causes the ‘dub’ sound?
closing of semilunar valves
what is the hardening and narrowing of the arteries due to cholesterol deposits called?
atherosclerosis
how can atherosclerosis lead to a heart attack? (6)
- atheromas develop in arteries -> significantly reduce diameter of e lumen
- restricted blood flow -> incr pressure -> damage to arterial wall fr shear stress
- damaged region is repaired w fibrous tissue -> significantly reduces elasticity of vessel wall
- smooth lining of artery is progressively degraded -> atherosclerotic plaques form
- if plaque ruptures -> blood clotting triggered -> forms a thrombus
- thrombus occludes coronary artery -> O2 and glucose cannot be transported to heart muscle cells -> heart attack
