Lecture 12: Circulation Flashcards
What are vertebrate characteristics of the circulatory system?
- Blood cells contain hemoglobin
- Closed circulatory system
- Heart is compartmentalized into chambers
- Aorta positioned in front of spinal column, behind viscera
What are the tetrapod characteristics of the circulatory system?
- reduced number of aortic arches
- Pulmonary circulation (gills or lungs oxygenate blood)
What are the mammalian characteristics of the circulatory system?
- Pulmonary and systemic circuit chambers in heart completely isolated from each other
- Aortic arch on left
- Involvement in regulation of body temperature (homeotherms)
What is the one main characteristic specific to humans of the circulatory system?
-Increased efficiency in keeping brain cool
What is hemolymph, what type of organisms have this, ad what does it occupy?
Circulatory fluid of invertebrates, occupies homecoels
**different from hemoglobin because it uses hemocyanin and copper
What is an open circulatory system?
Blood is pumped into body cavities (hemocoels) where tissues are surrounded by blood (hemolymph)
What does the color of blood depend on?
The protein that is used to transport oxygen
How many chambers of the heart do fish have?
1 ventricle 1 atria
How many chambers of the heart do amphibians have?
2 atria, 1 ventricle
How many chambers of the heart do reptiles have?
2 atria 2 ventricle
How many chambers of the heart do mammals and birds have?
2 atria and 2 ventricles
The sequence of the ________ ________- ________-_________-__________ _______ in the primitive heart is mirrored in living fishes an din the early-stage human embryonic heart
Sinus venosus-atrium-ventricle-conus arteriosus
What is the sinus venosus?
Confluence of major veins (bringing blood to heart)
What is the conus arteriosus?
Strongest contraction; pumps blood out to vessels
There transition from the primitive four chambered heart to the modern mammalian is an excellent example of how evolution can work within what?
The framework of ontogenetic sequences to changes a developmental process by extending it in a new direction
What is “ontogeny recapitulating phylogeny”?
During their development, organisms repeat evolutionary stages of ancestral species
**this doesnt actually occur
The observation that many even distantly related species resemble each other at early developmental stages reflects how changes in developmental timing (__________), and/or the retention of juvenile characteristics in some species (________) are ways in which evolution works within already existing complex systems.
Heterochrony
Neoteny
How doe the atrioventricular valves function?
OPEN:
1. Blood returning to the heart fills atria, putting pressure against AV valves; forced open
2. As ventricles fill, AV valve flaps hang limply into ventricles
3. Atria contract, forcing additional blood into ventricles
CLOSE:
1. Ventricles contract forcing blood against AV valve cusps
2. AV valves close
3. Papillary muscles contract and chordae tendineae tighten, preventing valve flaps from everting into atria
How do the Aortic and semi-lunar valves function?
- As ventricle contract and intraventricular pressure rises, blood is pushes up against semilunar valves, forcing them open.
- As ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing them to close
Which arteries make up the branches of left coronary artery and what is another name for these?
- Circumflex artery
- Anterior interventricular artery
**A.k.a. Left anterior descending (LAD)
Where do the coronary arteries come off of?
The ascending aorta
What does the pulmonary circuit consist of?
The chambers on the right side of the heart (R Atrium and ventricle) as well as the pulmonary arteries and veins
What does the systemic circuit consist of?
Chambers on the left side of the heart (L atrium and ventricle), along with all the other named blood vessels
Blood pumped out of the R ventricle is pumped into what?
Pulmonary artery to the lungs
The pulmonary trunk bifurcates into what two things?
L pulmonary artery and R pulmonary artery
What are the 2 branches of the R coronary artery?
Posterior interventricular artery
R marginal artery
Mammalian fetal circulation reflects the reliance of the developing fetus on what?
Maternal blood supply
Are fetal lungs functional? How do they develop?
Not functional, no pulmonary circuit yet but enough blood to allow lungs to develop
Where does oxygenated blood from the placenta pass through in the fetus?
From placenta through liver, enter the IVC, flows into the R atrium of heart
Are the atria fully separated in the fetus?
No, some blood form the IVC flows through the foramen oval into the R atrium
Where does blood from the SVC in the fetus flow into? Why?
The R ventricle this functions to reduce volume and pressure of blood pumped into the R ventricle
What allows more blood to be diverted away from the lungs and into the aorta and out to the fetal body?
Ductus arteriosus between the aorta and the pulmonary trunk
In the fetus, where is the most highly oxygenated blood diverted to?
The developing heart tissue and itself and the brain
The ductus arteriosus becomes what in the newborn?
Ligamentum arteriosum
The foramen ovale in the fetus becomes what in the newborn?
Fossa ovalis
The ductus venosus in the fetus becomes what in the newborn?
Ligamentum venosum
The umbilical vein in the fetus becomes what in the newborn?
Ligamentum teres
The umbilical arteries in the fetus becomes what in the newborn?
Medial umbilical ligaments
What happens tot he vessel of the umbilical cord at birth?
The vessels empty and collapse
What happens to the lungs at birth?
Empty of fluid and resistance to blood flow drops
The constricting of what in the fetus allows blood to flow into the pulmonary arteries at birth?
Ductus arteriosus
The overlapping flaps of the soon-to-be ______ ________ to close off the foramen ovale.
Interatrial septum
What 2 things drain into the brachiocephalic veins that become the superior vena cava?
Right and left internal jugular veins
Where does the blood supply to the head and neck originate form? Right and left side?
Aortic arch
Right side=brachiocephalic trunk (R. Common carotid and R subclavian)
Left side=L common carotid and L subclavian
What sits to the R of the ascending aorta?
SVC, right auricle
What sits to the L of the ascending aorta?
Pulmonary trunk
What is the arterial supply to the brain?
Vertebral arteries
internal carotid arteries
What is the arterial supply to the head?
External carotid arteries
What is the arterial supply to the neck?
External carotid arteries Thyrocervical trunks (from subclavian)
What drains the brain?
Rural sinuses to the internal jugular veins
What drains the head?
Internal jugular veins
External jugular veins
Vertebral veins
What drains the neck?
Internal jugular veins
External jugular veins
What are the dural sinuses of the brain?
- Straight sinus
- Occipital sinus
- Marginal sinuses
- Transverse sinus
- Sigmoid sinus
- Superior sagittal sinus*
- Inferior sagittal sinus
- Cavernous sinus
- Superior petrosal sinus*
- Inferior petrosal sinus*
-What is the cerebral arterial circle or circle of Willis important for?
An important anastomosis of arteries around the sella turcica (sphenoid bone)
What is the circle of Willis (cerebral arterial circle) formed from?
- Posterior cerebral arteries
- Posterior communicating arteries
- Internal carotid arteries
- anterior cerebral arteries
- Anterior communicating arteries
What is the actual function of the circle of Willis?
It equalizes blood pressure in the brain and can provide collateral channels should one vessel become blocked
How does the external carotid artery vary between macaque and humans?
Similar branching pattern to that of humans except for origin of maxillary artery
Is the internal carotid artery similar in macaque and humans?
Yes
How does the circle of Willis in macaque compare to those of humans?
It lacks an anterior communicating artery but instead the anterior cerebral artery unite to form one artery
What vessel supplies the coronary arteries?
Ascending aorta
What are the 2 parts of the descending aorta?
Thoracic part and abdominal part
What are the 4 main groups of arteries found in the thoracic portion of the descending aorta?
- Intercostal arteries
- Bronchial arteries
- Mediastinal arteries
- Esophageal arteries
What does the azygos veins receive blood from?
- R intercostal veins
- Hemi-azygos v.
- R. ascending lumbar v.
- Bronchial veins
- most esophageal vv.
- Most mediastinal vv.
What does the azygos v. Itself drains into?
Superior vena cava
What do the hemi-azygos and accessory hemi-azygos veins receive blood from?
- L. Intercostal veins
- L. Ascending lumbar v.
- Bronchial veins
- Some lower esophageal vv.
What is the internal vertebral venous plexus? What is its function?
It is a network of veins within the vertebral canal, surrounding the spinal cord and its coverings. It functions to return blood from the spinal cord and meninges. This plexus drains into the azygos system and then into the superior vena cava (SVC).
What was determined to be the main intermediary between the SVC and internal vertebral venous system?
The azygos system
Is there a functionally important connection between the lower azygos and hemi-azygos veins to the inferior vena cava?
No and the Bowsher article confirmed this
The azygos system also functions in mediating the ______ pressure
CSF
What branch of the abdominal aorta goes to the diaphragm?
Inferior phrenic
Which branches of the abdominal aorta go to the GI tract?
Celiac, superior and inferior mesenteric
What branches of the abdominal aorta go to the other organs not part of the gut tract?
Suprarenal, renal, gonadal (ovarian and testicular)
Which branches of the abdominal aorta go to the body wall?
Lumbar arteries, these are analgous to intercostal arteries
Where is the sympathetic chain in relation to the abdominal aorta?
Left lateral
Where is the pancreas , splenic vein, left renal vein, 3rd part of duodenum, mesentary, nodes, autonomic plexus, lesser sac, stomach, omentum and small bowel in relation to the abdominal aorta?
Anterior
Where it Y12-L4 and the left lumbar veins in relation to the abdominal aorta?
Posterior
What is the hepatic portal system?
A venous network that drains the GI tract and shunts the blood to the liver for processing and absorption of transported materials
What does blood exit the liver through? What do these merge with?
Hepatic veins that merge with the inferior vena cava
Why is the hepatic portal system needed?
Because the GI tract absorbs digested nutrients and these nutrients must be processed and/or stored in the liver
What are the 3 main things that make up the hepatic portal system?
Splenic vein
Superior mesenteric vein
Inferior mesenteric vein
What artery supplies the midgut?
Superior mesenteric
What artery supplies the foregut?
Celiac trunk
What are the 3 arterial branches of the celiac trunk?
Left gastric a.
Splenic a.
Common hepatic a.
What artery supplies the hindgut?
Inferior mesenteric
