Mediastinum - Middle Part 2 Flashcards
Name the valves of the heart:
Atrioventricular valves:
Tricuspid - RA to RV
Bicuspid - LA to LV
Chordae tendinae connects AV valves to papillary muscles
Semilunar valves:
Pulmonary valve - RV to pulmonary trunk
Aortic valve - LV to aorta
Control flow of blood into great arteries
Describe the sounds of the heart:
“Lub” - AV valves closing
“Dub” - semilunar valves closing
Murmurs occur when there is a dysfunction in the valves
Describe the conducting system
In diastole, pace is set by the sinoatrial node
In systole, the impulse travels to the atrioventricular bundle of His & atrioventricular bundle branches to stimulate ventricular contraction
Blood is then pumped into aorta and pulmonary trunk
While this happens, the atria are relaxed and refilling
Describe the components of the conducting system:
Sinoatrial node;
Pacemaker located in wall of right atrium
Deep to epicardium and has its own blood supply
Atrioventricular node - Located in septum between atria
Bundle of His - Bundle of fibres that enter interventricular septum, divides into 2 branches of Purkinje fibres
Purkinje fibres - found in dense CT of endocardium, specialised cardiac muscle fibres
Describe the coronary supply:
Right and left coronary supply anastomose with each other
Aortic sinuses - first branch of aorta
Lie in coronary sulcus
Provides a rich blood supply
Describe the right coronary supply:
Right coronary artery
Runs in coronary sulcus
Supplies SA node
Has a right marginal branch
Posterior inter ventricular
What are the key veins in the heart ?
They follow great arteries
Great cardiac vein, follows anterior inter ventricular artery
Middle cardiac vein, follows posterior inter-ventricular artery
Small cardiac vein, follows right marginal artery
Describe the nervous innervation of the heart:
Sympathetic and parasympathetic fibres from the autonomic branch of the peripheral nervous system
Cardiac plexus - right and left vagus nerves, as well as contributions from the sympathetic trunk
Responsible for influencing heart rate, cardiac output, and contraction forces of the heart
Heart and visceral serous pericardium are innervated by visceral nerves
myogenic
Describe the sympathetic nervous system:
Responsible for fight or flight response
Sympathetic nerves arise from T1-L2 spinal nerves only
Nerves enter the sympathetic chain via the white rami comunicans, and can run up or down
Can sometimes synapse at the same level
Nerves leave sympathetic chain via grey rami comunicans to join other spinal nerves
Describe the sympathetic chain
Consists of a series of interconnected ganglia and nerve fibres that extend alongside the vertebral column
Integral to the “fight or flight sympathetic response
chain allows for communication between different levels of the nervous system, enabling coordinated responses
Paired ganglia at every level except - cervical ganglia + ganglion impair
Describe the sympathetic ganglion:
Location of synapses of nerves
Each ganglion contains two nerves: a pre-ganglionic neurone and a post ganglionic neurone
Thoracic or upper limb sympathetic nerves synapse in the para-vertebral sympathetic ganglia
Relay station
Coordination of responses
Describe splanchnic nerves;
Sympathetic splanchnic nerves;
- carry preganglionic sympathetic fibers from the sympathetic trunk to prevertebral ganglia in the abdomen
- arise from T5-T12
- modulate visceral blood flow and vascular tone
Parasympathetic splanchnic nerves;
- carry preganglionic parasympathetic fibers from the sacral region (S2-S4) and visceral sensory fibers
- don’t pass via sympathetic chain
- stimulate smooth muscle contraction in the GI tract to enhance digestion
What is homeostasis ?
Process by which the body maintains a stable internal environment
Balancing various bodily functions like temperature, blood sugar levels, and pH balance
Continuous adjustment helps keep the body functioning properly
Describe a heart attack:
In a heart attack visceral sensory signals return to the CNS via spinal nerves T1 - T5
The brain interprets this as the T1 - T5 somatic sensory nerves
T1 - T5 somatic nerves supply the T1 - T5 dermatomes
Produces pain down the arm
What are the different types of splanchnic nerves ?
Greater; T5 - T10, Synapses in the celiac ganglion
Lesser; T10 - T11, Synapses in the superior mesenteric ganglion
Least; T12, Synapses in the renal ganglion
Lumbar - L1-L2, Synapse in the inferior mesenteric ganglion
Sacral - S2-S4
