CAR Flashcards
What is the hearts function?
mechanical pump
What is arteries function?
transport usually oxygenated blood away from the heart
What are veins function?
transport usually deoxygenated blood towards the heart
What are capillaries function?
they are the site of exchange of substances
What is the function of blood?
Transport of cellular components and dissolved substances
What is the function of the lymphatic system?
to return tissue fluid to systemic circulation
in brainscape folder match species comparison of circulation
fish, mammal, amphibian
what phrase describes mammalian circulation?
double closed circulation
Fill in the gaps
The right atrium receives ?????? blood from around the body via the ??????
The left atrium receives ???????blood from the lungs via the ????????
deoxygenated, vena cava, oxygenated, pulmonary vein
in blood vessels what is the tunica media?
the concentric sheets of smooth muscle
in blood vessels what is the tunica interna?
endothelial lining (innermost tunica (layer) of an artery or vein)
what is the lumen of a blood vessel?
cavity of the organ
in blood vessels what is the tunica externa/adventitia?
connective tissue sheath around vessel
what are elastic arteries?
Conducting artery, expand during systole and recoil during diastole
What are muscular arteries
Medium sized, changes (vaso constriction/vasodilation) affect blood pressure
Describe capillaries
small diameter, endothelial layer only
describe arterioles
Small diameter, which changes in response to local conditions e.g. O2 levels
identify structures of the heart diagram in BrainScape folder unanswered
look at answered version
What are the 2 atrioventricular valves and which one is on what side?
tricuspid (right) mitral/bicuspid (left)
What are the 2 semilunar valves and which one is on what side?
pulmonic (right) and aortic (left)
what is meant by a cardiac cycle?
Each complete contraction and relaxation of the heart is called a cardiac cycle. There are two main parts to the cardiac cycle: systole and diastole
What is systole?
During systole the heart muscle contracts
what is diastole?
During diastole the heart muscle relaxes
describe the processes and steps of the cardiac cycle?
- When ventricular pressure becomes lower than atrial pressure the AV valves open
- Ventricles fill with blood.
Atria contract and force more blood into ventricles - The ventricles contract, increasing the ventricular pressure
- When the ventricular pressure increases above atrial pressure, the AV valve close
- When the pressure inside the ventricles exceeds the pressure in the outgoing arteries, the semilunar valves open
- . As a result of ventricular systole and opening of the semilunar valves, blood flows from ventricles into the arteries
- Pressure in ventricle drops below aortic pressure. The Semilunar valves close
functions of the cardio-respiratory system
Transport – to and from metabolising tissue
Oxygen and carbon dioxide
Nutrients
Waste
Heat
Hormones
Homeostasis
pH, osmolarity, electrolytes etc
Infection
Other
Generate pressure (eg renal filtration)
What does heart disease normally involve?
Disease usually involves valve degeneration, and the valve becoming incompetent or diseases of the heart muscle, resulting the heart not contracting well OR not filling well
what is cardiac output and stroke volume?
volume delivered into the circulation per minute
volume delivered by the ventricle per beat
What is heart failure?
Heart failure is a syndrome in which the heart fails to deliver blood effectively to meet the requirements of metabolising tissues
What happens during ventricular systole?
Ventricular systole = contraction of ventricles
Results in cardiac output
Atrioventricular valves close
The source of the first heart sound – “Lub”
What are important controlling factors of venous return?
Important controlling factors:
Sympathetic nervous system
Blood volume
Muscle (respiratory) pump
what is venous return?
process by which deoxygenated blood is returned to the heart
what are portal veins?
portal veins are found between two capillary beds (site of diffusion)
what is the fancy name for cardiac ultrasound?
echocardiography
have a go at labelling the renal portal system in brainscape
look at the labelled version
what regulates portal blood flow?
renal portal valve
what is the function of the renal portal system
Receives blood from caudal body and returns it to the heart via the kidneys
label the 5 zones of the primitive tube from which the mammalian heart develops are very similar to the heart of the primitive fish and anurans in brainscape folder
look at answer
How many chambers are in aa fish heart? describe its blood flow
Simple cardiovascular system
“2 chambers” to the heart
Blood flows in one direction effectively through a single atrium and ventricle (technically there are 6 chambers similar to the primitive tube)
Vasculature includes gills to accommodate oxygenation
Heart is often positioned ventral and caudal to the gills
how many chambers are in an amphibians heart? describe its blood flow?
In anurans we start to see 2 atria – 3 chambers in total
Oxygenation occurs from lungs, skin and buccal cavity hence vasculature more complex compared to mammals
Heart is mid cranial coelom
Like birds they have no diaphragm, hence the term coelom again
how many chambers do most reptiles have? describe its blood flow
Most reptiles have 3 chambers, with 2 atria and 1 ventricle. The ventricle is split into 3 sections by folds in the muscle wall
Crocodiles are an exception with 4 chambers but distinct differences from mammals still (2 x aortas)
All reptiles can shunt blood away from the respiratory tract when needed.
For most species the heart is mid cranial coelom, some very cranial (base of the neck).
For snakes the heart is often found in the cranial third of the body.
What is the cardio-respiratory systems functions?
Transport – to and from metabolising tissue
Oxygen and carbon dioxide
Nutrients
Waste
Heat
Hormones
Homeostasis
pH, osmolarity, electrolytes etc
Infection
Other
Generate pressure (eg renal filtration)
What is heart failure?
Heart failure is a syndrome in which the heart fails to deliver blood effectively to meet the requirements of metabolising tissues
What is name for cardiac contraction and relaxation?
systole and diastole respectfully
What does ventricular systole result in?
Ventricular systole = contraction of ventricles
Results in cardiac output
Atrioventricular valves close
The source of the first heart sound – “Lub”
What does ventricular diastole result in?
Ventricular diastole = relaxation of ventricles
Results in ventricular filling
Semi-lunar valves close
The source of the second heart sound – “Dub”
What are the 2 methods of regulating cardiovascular function? Describe how these work?
regulation of cardiac function and regulation of the vasculature.
Regulation of cardiac function
Need to consider:
Can change heart rate and contractility
Electrical activity (Electrophysiology)
Assessment of this using an ECG
Contractile function control
The important role of the autonomic nervous system
Hormonal mechanisms (local and systemic)
Regulation of the vasculature
Autoregulation - local blood flow regulation, intrinsic ability of an organ to maintain a constant blood flow despite changes in perfusion pressure.
The important role of the autonomic nervous system
Hormonal mechanisms (local and systemic)
What does contractility mean?
the strength of contractions
What do you have to consider as the heart as a pump?
Cardiac Output (volume delivered into the circulation per minute)
Stroke Volume (volume delivered by the ventricle per beat)
Other pumping mechanisms (venous)
….and what control these
What do you have to consider for the distribution of blood within the heart and vasculature?
Vascular constriction and dilation – arteries AND veins
The maintenance of unidirectional flow in vital organs
Cardiac valves
Vascular valves
What is cardiac output?
Is the amount of blood pumped per minute
What are the important controlling factors of venous return?
Sympathetic nervous system
Blood volume
Muscle (respiratory) pump
Where are portal veins found?
between 2 capillary beds
Look at heart of different animals unlabelled and try and complete in brainscape folder
look at answered version
What are the main features of the avian CNS? And where is the heart located?
Main features of the avian CVS:
4 chambered heart similar to mammals mammals
AV valves are different in structure compared to mammals
The heart is located within the cranial ventral coelom and is surrounded by air sacs
Term coelom is used because birds don’t have a diaphragm
How to birds mainly increase cardiac output?
By increasing heart rate (115-670BPM)
How to birds heart size fluctuate
they increase prior to migration in migratory species
Key points surrounding avian cardiac function
Ventricles
Left sided ventricular wall 3x thicker than right
Empty almost completely on each cardiac cycle
Low end-systolic volume
What type of animals have a renal portal system?
What is its role and function?
And what is its clinical importance?
Reptiles, birds, amphibians and most fish – not in mammals
Receives blood from caudal body and returns it to the heart via the kidneys
It functions to supply blood to renal tubules at all times
Portal blood flow regulated by renal portal valve.
Alters how drugs will act in these species: for example if injected in caudal half of the body then maybe metabolised before entering general circulation
Look at renal portal system unlabelled in BrainScape folder
Look at labelled version
Label the 5 primitive zones of the primitive tube
Look at the labelled answered version
Important features of the fish cardiac system
Simple cardiovascular system
“2 chambers” to the heart
Blood flows in one direction effectively through a single atrium and ventricle (technically there are 6 chambers similar to the primitive tube)
Vasculature includes gills to accommodate oxygenation
Heart is often positioned ventral and caudal to the gills
Important features of the amphibian heart
In anurans we start to see 2 atria – 3 chambers in total
Oxygenation occurs from lungs, skin and buccal cavity hence vasculature more complex compared to mammals
Heart is mid cranial coelom
Like birds they have no diaphragm, hence the term coelom again
Label components of the amphibians heart (unlabelled)
Look at the answer version
Important features of the reptiles heart
Most reptiles have 3 chambers, with 2 atria and 1 ventricle. The ventricle is split into 3 sections by folds in the muscle wall
Crocodiles are an exception with 4 chambers but distinct differences from mammals still (2 x aortas)
All reptiles can shunt blood away from the respiratory tract when needed.
For most species the heart is mid cranial coelom, some very cranial (base of the neck).
For snakes the heart is often found in the cranial third of the body.
What are the principle functions of the circulatory system
Transport
- Delivers O2 from lungs and nutrients from digestive system
Removes waste, heat and CO2 from tissues
Hormones
Protective function – carries WBC and Ig
Homeostasis – pH, ions, fluid volume
Pressure
Complete local circulatory rules
Where do the kidney renal artery go to , and the efferent arterioles?
Look at answered version
Kidney renal artery to the glomerulus, efferent arterioles takes oxygenated blood to the kidney tissue
What percentage is the heart approximately of body weight?
0.75% - relatively larger in smaller animals
What are the landmarks of the heart?
Ventral border of the lungs
Cardiac notch (L>R)
Lungs laterally
Phrenic nerve
Thymus cranially
Diaphragm caudally
What does the thymus do?
produces and trains t-cells
What does the phrenic nerve innervate?
motor innervation to the diaphragm
Complete thorax landmarks diagram
Look at completed version
Where does the heart lie in the dog? What percentage of the heart lies to the median plane?
in mediastinum (The mediastinum is a space in your chest that holds your heart and other important structures)
60% is to the left of the median plane
Where does the apex of the heart sit? How do the right and left ventricle sit? Is the base dorsal or ventral) What ribs are in the lateral projection of the heart?
Apex sits in sternum – costochondral junction 6
Right ventricle is CRANIAL to left!
Base is dorsal
Ribs 3-6
What is the coronary groove?
What do the paraconal groove and subsinual groove mark? Which one is cranial and caudal?
groove that splits the atria from the ventricles. It is also where the coronary arteries sit in
Paraconal and subsinuosal groove mark where the septum is. Pulmonary artery is on the right side.
Paraconal groove cranially
Subsinuosal groove caudally
What is the pericardium? and What does it contain?
Sac surrounding the heart
Inner visceral layer on surface of the heart
Outer parietal layer
No significant lumen
Where is the intervenous tubercle found and what is its role?
Intervenous tubercule diverts blood into the atrium.
What are the 2 names of the vena cava in animals?
What does the azygous veins do?
cranial and caudal vena cava, intervenous tubercle sits in the middle of these at the point at which they meet
It brings blood back from the thorax
What does the trabecula septomarginalis do?
Trabecula septomarginalis (also known as the moderator band) ensures communication is quick on both sides found in the right ventricle
What occupies all of apex in the heart?
Occupies all of apex
How many cusps does the tricuspid and bicuspid (mitral valve) have?
What is the name for the heart strings?
2 cusps
Chordae tendiae - papillary muscles
What is the name of the right and left semilunar valves and how many cusps do they have?
R semilunar - pulmonic
L semilunar - aortic
3 cusps
When do the semilunar valves open
When pressure in ventricles exceeds that of aorta and pulmonary artery
What is the myocardium?
The myocardium is the middle muscular layer of the heart, situated between the inner endocardium and the outer epicardium. Also known as the cardiomyocytes
What is the epicardium?
The outer layer of the heart wall that protects the inner layers and produces pericardial fluid. Also known as the visceral pericardium
What is the endocardium?
The endocardium is the innermost layer of tissue that lines the chambers and valves of the heart. It is composed of a thin, smooth tissue that serves as a barrier between the cardiac muscles and the bloodstream, ensuring efficient blood flow.
Describe the structure of cardiomyocytes
Large, cylindrical cells
Striated (myofibrils) – like skeletal m.
Short, branched fibres
Lots of mitochondria
What are intercalated discs? and what is there function?
Connect adjacent cardiac muscle cells. Allow for Cell-to-cell communication
Required for coordinated muscle contraction
What are purkinje fibres and why are they important?
Specialised conducting tissue
Deliver electrical activity to myocardium
Compare sympathetic nervous system and parasympathetic system in terms of neurons and target sites and regions
Sympathetic nervous system
Preganglionic neurons are relatively short and originate from the thoracic and lumber regions of the spinal cord.
Postganglionic neurons are relatively long and extend from the sympathetic ganglia to the target organs
Parasympathetic nervous systems
Preganglionic neurons are relatively long and originate from the brainstem and sacral (relating to the sacrum a triangular-shaped bone at the base of the back) regions of the spinal cord
Postganglionic neurons are relatively short and extend from the parasympathetic ganglia to the target tissues.
What type of receptors are involved in pre-ganglionic receptors in the SNS and PSNS? What neurotransmitter works on these and what is its designation?
Nicotinic acetylcholine receptors. Worked on by acetylcholine, designation is cholinergic
What type of receptors are involved in the adrenal medulla fibre (inner part of your adrenal gland)? What neurotransmitter works on these and what is its designation?
alpha and or beta receptors. Acted on by adrenaline (epinephrine) and its designation is adrenergic
What type of receptors are involved in post-ganglionic receptors in the SNS? What neurotransmitter works on these and what is its designation?
alpha and beta receptors. Noradrenaline (norepinephrine), adrenergic
What type of receptors are involved in post-ganglionic receptors in the PSNS? What neurotransmitter works on these and what is its designation?
muscarinic acetylcholine receptors, acetylcholine, nicotinic
What do alpha and beta receptors cause?
Alpha receptors stimulate effector cells and are responsible for vasoconstriction and increasing blood pressure. Beta receptors relax effector cells and are responsible for vasodilation and decreasing blood pressure.
What are adrenergic receptors?
Adrenergic receptors are a class of G protein-coupled receptors that are targets of many catecholamines like norepinephrine and epinephrine produced by the blood. Catecholamines are a monoamine neurotransmitter with a benzene group and two attached hydroxy groups (-OH) right next to each other
What are muscarinic acetylcholine receptors?
Muscarinic acetylcholine receptors are a type of acetylcholine receptors that are G protein-coupled receptors.
1) In what circumstance is the sympathetic NS activated?
It is activated in situations that require a fight or flight response, such as stress, physical activity, emergency situations and excitement.
What outflow from the CNS does the SNS have?
It has a thoracolumbar outflow as the SNS originates from the thoracic (T1 to T12) and lumbar (L1 to L2) segments of the spinal cord.
Where are the ganglia located in the SNS?
The ganglia in the SNS are located in specific regions that facilitate the relay of signals from the CNS to target organs.
Paravertebral ganglia (sympathetic chain ganglia) are on either side of the spinal column and extend from the base of the skull to the coccyx (tailbone). These are closely associated with the thoracic and lumbar regions of the spinal cord where the preganglionic neurons originate.
Prevertebral ganglia are located anterior (towards the front of) to the vertebral column, near major arteries
Adrenal medulla acts as a modified ganglion. It releases adrenaline and noradrenaline directly into the blood stream in response to sympathetic stimulation.
Complete organisation of the SNS unlabelled version
look at labelled version
When is the PSNS system activated?
The PSNS is activated during rest-and-digest situations, promoting relaxation, recovery, and maintenance of the body’s homeostasis. Specific circumstances causing this include relaxation, eating, resting and reproductive activities.
How does the outflow differ in the parasympathetic NS?
For PSNS you have a craniosacral outflow, the PSNS originates in the brainstem and the sacral (relating to the sacrum, a triangular-shaped bone at the base of the back) region of the spinal cord.
Which cranial nerves are involved in the PSNS?
The preganglionic neurons of the PSNS arise from the cranial nerves (oculomotor, facial, glossopharyngeal and Nictitans) as well as the sacral nerves which arise from the sacral spinal cord segments S2 to S4 and innervate the lower abdominal and pelvic organs.
Where are the ganglia located in the PSNS located and how does this differ to the SNS?
In the PSNS, the ganglia are located closer to or within the target organs they innervate. This is different from the SNS, where the ganglia are generally located near the spinal cord.
What are the name of the reflexes that acts as neural regulation of the ANS?
These work by a feedback cycle that involves which nervous system?
What 4 functions are controlled by these reflexes to maintain homeostasis?
autonomic reflexes. Autonomic reflexes regulate various involuntary bodily functions essential for maintaining homeostasis.
afferent nervous system
- Heart rate regulation
- Respiratory rate
- Digestive processes
- Pupil dilation and constriction
The SNS has 2 effects on the heart, what are they?
The 2 primary affects the SNS have on the heart is:
Increased heart rate (positive chronotropy) – SNS releases norepinephrine which binds to beta-1 adrenergic receptors in the heart. This interaction increases heart rate by accelerating the rate of depolarization of the SA node, the hearts natural pacemaker.
Increased force of contraction (positive inotropy) –norepinephrine binding to beta-1 adrenergic receptors also enhances the force of contraction of the heart muscle. This increases the volume of blood ejected with each beat improving the overall cardiac output.
What is the effect of the SNS on the lungs?
The SNS has several effects on the lungs, primarily through the activation of beta-2 adrenergic receptors in the bronchial smooth muscles,
The main effects:- bronchodilation – SNS stimulates the release of norepinephrine, which binds to the beta-2 adrenergic receptors in the bronchial smooth muscles. This leads to the relaxation of these muscles, causing the airways to widen. Bronchodilation increase the airflow into and out of the lungs, which is especially important during physical activity or stressful situations when the body’s oxygen demand is higher.
Decreased secretions –SNS can reduce mucus secretion in the airways, helping to keep them clear and improve airflow. This is achieved by inhibiting the activity of certain glands in the respiratory tract.
Compare the length of pre- and post- ganglionic fibres in the SNS?
Pre-G fibres are relatively short in length
Post-G fibres are relatively long in length
What are baroreceptors involved in? Where are they located?
Blood pressure receptors.
Carotid sinus, aortic arch
The carotid sinus, also known as the carotid bulb, is a neurovascular structure that appears as a dilation at the bifurcation of the common carotid artery into the internal and external carotid bodies. It is localized near the arterial pulse. Monitor blood pressure going towards the brain.
The aortic arch, arch of the aorta, or transverse aortic arch is the part of the aorta between the ascending and descending aorta. Monitor the blood pressure of the blood flowing through the systemic circulation.
What processes do chemoreceptors control? What is the location of these chemoreceptors?
They detect changes in the chemical composition of the blood and other bodily fluids.
- Peripheral chemoreceptors (carotid bodies, aortic bodies)
- Central chemoreceptors
Carotid bodies are small clusters of chemoreceptors located at the bifurcation of the common carotid arteries into the internal and external carotid arteries. They monitor the levels of oxygen, carbon dioxide, and ph in the blood.
Aortic bodies are located near the aortic arch and similarly monitor blood levels of oxygen, carbon dioxide and ph. They are less sensitive than carotid bodies but contribute to respiratory regulation.
Central chemoreceptors are located on the ventral surface of the medulla oblongata in the brainstem. They primarily monitor the ph of the cerebrospinal fluid which indirectly reflects the levels of carbon dioxide in the blood. These chemoreceptors play a crucial role in regulating the rate and depth of breathing.
What happens when blood loss occurs?
Baroreceptors firing frequency falls, which tells the CNS that BP is low, altered impulse frequency to the effector increasing HR and vasoconstriction, compensatory systems are activated
Where are the sympathetic cardiac nerves found in the heart?
within the cardiac plexus (network of nerves that innervate the heart)
Post ganglionic fibres in the heart go to the SA Node and AV Node (in the walls of the heart), what is the importance of this? What is the term used for this?
Controls rate and rhythm, another term for this (=ve/-ve) cardiac regulation effect
Post ganglionic fibres also go to the myocardium, what does this cause? what is another name for this?
Post-G fibres also go to the myocardium this controls the force of contraction
= +ve/-ve intropic effect
What does negative chronotropy mean and negative inotropy mean? What system does this affect?
Effects are generally opposite to that of the SNS. Negative chronotropy (decreased heart rate), negative inotropy (reduced force of contraction)
Up to slide 17 of ANS AND CNS
