Class notes
Human Biology notes
- Course
- Institution
Detailed notes on all of the lectures including many pictures
[Show more]
Seller
Follow
ninajunakovi
Content preview
HUMAN BIOLOGYLECTURE 1
HEART
− located between the lungs pointing towards the left
− 4 chambers: 2x atria (upper) + 2x ventricle (lower)
COMPARTMENTS
− valves:
o semilunar valves: pulmonary & aortic
o atrioventricular (AV) valves: left – bicuspid &
right – tricuspid → reinforced by chordae
tendineae = strong connective tissue that is also
in tendons
− coronary circulation:
o heart’s blood supply
o supplied by coronary arteries → the first branches of aorta
o drained by coronary veins → emptying into the right atrium
o myocardial infarction = heart attack, blockage in the coronary
arteries
BLOOD FLOW
− heart:
o superior vena cava & inferior vena cava carry deoxygenated
blood from the body to the right atrium → right AV valve →
right ventricle
o right ventricle → pulmonary valve → pulmonary trunk →
right & left pulmonary arteries → lungs
o lungs → right & left pulmonary veins → left atrium
o blood flows from the left atrium through the left AV valve to
the left ventricle
o the left ventricle pumps blood through the aortic valve into
the aorta
− pulmonary circuit:
o circulating blood through the lungs
o right atrium pumps deoxygenated blood into the right
ventricle which pumps it into the pulmonary trunk
o pulmonary trunk splits into right & left pulmonary arteries
which go to the lungs
, o in the lungs, pulmonary arteries branch into
arterioles which lead to capillaries → gas exchange
o pulmonary capillaries lead to venules which merge
into pulmonary veins
o 4 pulmonary veins empty into the left atrium
− systemic circuit = circulating blood through the body tissues
CARDIAC CYCLE
− atria contract together → ventricles contract together →
heart relaxation
− systole = heart contraction
− diastole = heart relaxation
− intrinsic control:
o right atrium
o sinoatrial (SA) node / pacemaker initiates the
heartbeat → sending out an electric signal → atria
contraction
o the impulse reaches the atrioventricular (AV) node →
a signal down the AV bundle and Purkinje fibers →
ventricular contraction
o ECG (electrocardiography) peaks: P = atrial
contraction, QRS = contraction of the ventricles, T =
relaxation of ventricles
− extrinsic control: cardiac control centre in the brain increases
or decreases the heart rate depending on body’s needs
BLOOD PRESSURE
− the pressure blood exerts against a blood vessel wall
− contraction of ventricles creates blood pressure → propels blood through the arteries
− highest in the aorta → gradually decreases as it flows through the vessels in the body
− slowest in the capillaries to increase the exchange of gases, nutrients, and waste → adjusted by
precapillary sphincters
− pulse = surge of blood into an artery that causes its walls to stretch and then recoil, 60-80 beats per
minute
− venous return:
o skeletal muscle contraction
o respiratory pump (breathing)
o valves
,HEART WALL
− endocardium = 1 flat layer of epithelium → endothelium, always bordering the lumen, also some
connective tissue
− myocardium = long heart muscle cells, connected with each other via intercalated disc (dark lines in
microscopy) that consists of cell-cell connections → adherens, desmosome, and gap junctions →
united contraction
− desmosome = arrangements of protein fibres tightly holding the membranes together to prevent
overstretching
− epicardium/pericardium = connective tissue, location of the big blood vessels, secretes pericardial
fluid for lubrication
− a lot of capillaries → continuous need for oxygen and glucose since the heart works nonstop
− left ventricle myocardium is thicker than the right ventricle since it pumps blood to the entire body,
not just the lungs
− ventricle myocardium is thicker than the atria one
BLOOD VESSELS
− aorta – muscular artery (1 cm) – arteriole (30-300 μm) – capillary (10 μm) – venule (30-300 μm) –
vein – vena cava (1 cm)
WALL
− tunica intima/internal layer:
o bordering the lumen
o endothelium with basal lamina
o subendothelial layer – connective tissue
o lamina elastica interna
− tunica media:
o mostly smooth muscle cells in circular layers
o surrounded by a bit of elastic and collagen fibres
− tunica adventitia/external layer:
o connective tissue – elastin and collagen fibres
o longitudinal smooth muscle cells
o vasa vasorum = small blood vessels in the external
layer
, − elastic & muscular arteries
− aorta: the only elastic artery in the body → a lot of extra amounts of elastic fibre in media since it
receives a lot of blood
− arteriole:
o small diameter
o endothelium, elastica
interna
o very few layers of
smooth muscle cells in
the media
− venule:
o small diameter
o endothelium, NO
elastica interna
o very few layers of
smooth muscle cells in
the media
− veins:
o relatively wide lumen
o valves = intima extensions helping blood flow from the bottom to the top (opposite of
gravity) towards the heart
o NO elastic interna
o thin media with circular smooth muscle cells
o thicker external layer
− capillaries:
o very small diameter
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller ninajunakovi. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.55. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
67163 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now