Blood Vessels & Compossition Flashcards
What is tunica interna (or intima)?
Innermost layer of the blood vessel and adjacent to lumen (space inside)
What is tunica media?
Middle layer of blood vessel made of smooth muscle and elastic fibers (threads of protein)
What is tunica externa (or adventitia)?
Outermost layer adjacent to surrounding tissue
Does the exchange of nutrients and gases normally happen at the level of arteries/veins?
No, but they can exchange in the capillaries
What are arteries?
Medium/large vessels branching from the aorta
What are arterioles?
Arteries divide into smaller vessels called arterioles
What are capillaries?
Arterioles feed into smaller capillaries that form capillary beds in the body’s tissues. They allow O2/nutrients to go into the cell and CO2/waste to be removed.
What are venules?
Blood journeys from capillaries to small vessels called venules (the smallest veins)
What are veins?
Venules combine into veins and eventually become the inferior/superior vena cava that empties into the heart.
Arteries carry oxygenated or deoxygenated blood from the heart to the tissues?
Oxygenated
Arterial walls are…?
Elastic allowing them to absorb pressure created by the ventricles pumping
The smooth muscles in the arteries’ tunic media allow arteries to regulate…?
Arteries can regulate their diameter
What are the types of arteries? (2)
Elastic, muscular
Elastic arteries function as…?
Pressure reservoirs
What are some characteristics of elastic arteries (aka conducting arteries)? (4)
- Large diameter (aorta)
- More elastic fibers, less smooth muscle (hence the name)
- Tunica media is thick and has many elastic fibers
- Well-defined external elastic membrane
What are some characteristics of muscular arteries (aka distributing arteries)? (5)
- Medium diameter
- More smooth muscle, less elastic fibers
- Distributes blood to various parts of body
- Thick tunica media dominated by smooth muscle
- Thin external elastic membrane
What is anastomosis of arteries?
When 2 or more arterial branches supplying the same region of body join together creating an alternate blood route
When can anastomosis not occur in arteries supplying the same region?
If an end artery is blocked (necrosis can occur to that region)
What do capillaries connect together?
Arterioles and venules
Capillary walls are composed of…? (2)
Single layer of cells (endothelium) + basement membrane
Because capillary walls are thin, what can capillaries do?
Capillaries allow the exchange of nutrients and waste between blood and tissue cells
What is the precapillary sphincter?
It is a mechanism that allows a certain amount of blood and nutrients to enter the diffusion area
What does the precapillary sphincter have the ability to do? (2)
- Equalize pressure and RBC flux
- Protect downstream capillaries and brain tissue against adverse blood pressure
What are continuous capillaries?
Least permeable capillary only allowing small solutes to pass through
Continuous capillaries support which parts of the body? (5)
Brain, endocrine system, kidneys, lungs, small intestines
What are fenestrated capillaries?
Tiny blood vessels with small pores (windows)
What is the function of the fenestrated capillaries’ small pores?
Increases flow of nutrients, waste, and other substances from capillaries to surrounding organs
What are sinusoid capillaries?
A special type of capillary with a wide diameter
Where can you find sinusoid capillaries? (5)
Liver, spleen, lymph nodes, bone marrow, endocrine glands
Sinusoid capillaries can also be…?
Continuous, fenestrated, or discontinuous
How are venules formed?
The union of several capillaries
Venules drain blood from…?
Capillaries into veins
What are the types of venules? (2)
Postcapillary, muscular
What are the main functions of postcapillary venules? (3)
- Pass blood into muscular venules
- Permit the exchange of nutrients/wastes between blood and interstitial fluid
- Function in white blood cell emigration
Which are larger in diameter: postcapillary or muscular venules?
Muscular venules
Which layers can you find postcapillary or muscular venules? (2)
Endothelium, basement membrane
What are the main functions of muscular venules? (2)
- Pass blood into veins
- Act as reservoirs for accumulating large volumes of blood (with postcapillary venules)
How are veins formed?
The union of several venules
How do veins’ layer thickness vary when compared to arteries?
Veins have a thinner tunica interna/media and a thicker tunica externa
Veins have more or less elastic tissue and smooth muscles than arteries?
Less elastic tissue and smooth muscle
What is another name for the large portion of blood in systemic veins/venules at rest?
Blood reservoirs
Do veins have valves?
Yes
What is the role of pulmonary veins?
They transport oxygenated blood by the lungs to the heart
What is the cause of varicose veins?
Increased blood pressure in the veins
What happens if the veins’ valves become weak or damaged?
Blood collects in the veins (varicose)
What is the appearance of varicose veins?
Veins are dilated and twisted
What are spider veins?
Dilated venules close to the skin, especially in lower limbs and face (they look like webs)
How do substances cross capillary walls? (3)
Diffusion, transcytosis, bulk flow
What are some examples of substances that can cross capillary walls via simple diffusion? (5)
O2, CO2, glucose, amino acids, some hormones
What is transcytosis?
The process of large, lipid-insoluble molecules (e.g. insulin) crossing capillary walls in vesicles
What is bulk flow?
A passive process when large numbers of ions, molecules, or particles move together in the same direction
Bulk flow occurs from what to what pressure?
Higher pressure to lower pressure (continues as long as pressure difference exists)
Bulk flow regulates..?
Relative volumes of blood and interstitial fluid
What is filtration?
The pressure-driven movement of fluid/solutes from blood capillaries into interstitial fluid
hich types of pressure promote filtration? (2)
Blood hydrostatic (BHP), interstitial fluid osmotic (IFOP)
What is reabsorption?
The pressure driven-movement of fluid/solutes from the interstitial fluid into blood capillaries
What types of pressure promote reabsorption?
Interstitial fluid hydrostatic (IFHP), blood colloid osmotic (BCOP)
How do you calculate the net filtration pressure (NFP)?
Pressures promoting filtration minus pressures promoting reabsorption [(BHP+IFOP)-(BCOP+IFHP)]
What are the factors affecting blood flow? (7)
Cardiac output (CO), mean arterial pressure, blood volume, vascular resistance, vasocontraction, blood viscosity, venous return
What is blood flow?
Volume of blood that flows through any tissue in a given time period (mL/min)
What are two ways to calculate cardiac output?
- Heart rate (HR) * stroke volume (SV)
- Mean arterial pressure (MAP) / resistance (R)
What is the mean arterial pressure?
Average arterial pressure throughout the body after it leaves LT ventricle until it enters RT atrium
What is blood volume?
Amount of blood circulating blood vessels at any given time
What is vascular resistance?
Force exerted on blood vessel wall
What is vasoconstriction?
- Narrowing of lumen (space) of blood vessel
- ⬆️ vasoconstriction = ⬆️ resistance
What is blood viscosity?
- Thickness of blood
- ⬆️ viscosity = ⬆️ resistance
What is venous return?
Amount of blood returns to RT atrium
What are some factors that increase venous return? (4)
Increased blood volume, skeletal muscle and respiratory pumps, vasoconstriction
What increases mean arterial pressure (MAP)?
Increased cardiac output (CO), increased systemic vascular resistance (SVR)
What is the signal pathway of neg. feedback regulation of blood pressure? (3)
- Baroreceptors detect if BP is too high or low
- Baroreceptors send a signal to the hypothalamus
- The hypothalamus sends a message to the heart, blood vessels, and kidneys (effectors in BP regulation)
What is the role of the medulla oblongata?
The cardiovascular center (group of neurons regulating HR, contractility, and blood vessel diameter)
What are baroreceptors?
- Pressure-sensitive sensory neurons monitoring blood vessel and atrial wall stretching
What are the effects of norepinephrine and epinephrine?
- Increases BP (HR, contractility)
What are the effects of angiotensin II, antidiuretic hormone (ADH — increases H2O reabsorption), and norepinephrine/epinephrine?
- Increases BP (vasoconstriction aka narrowing of vessel)
What are the effects of atrial natriuretic peptide (ANP), epinephrine, and nitric oxide?
- Decreases BP (vasodilation aka widening of vessel)
What are the effects of aldosterone (increases Na reabsorption) and antidiuretic hormone?
- Increases BP (blood volume increase)
What are the effects of atrial natriuretic peptide?
- Decreases BP (blood volume decrease)
What is the autoregulation of BP? (2)
- A regulatory mechanism allowing blood flow in a vascular bed to remain constant during variations of arterial pressure
- Ability of a tissue to automatically adjust blood flow to match metabolic need for delivery of O2/nutrients + removal of waste
Where is the superficial temporal artery?
Medial to ear
Where is the facial artery?
- Mandible (lower jawbone) in line with corners of mouth
Where is the common carotid artery?
Lateral to larynx (voice box)
Where is the brachial artery?
Medial side of biceps brachii muscle
Where is the femoral artery?
- Inferior to inguinal ligament
Where is the popliteal artery?
- Posterior aspect of knee
Where is the radial artery?
- Lateral aspect of wrist
Where is the dorsalis pedis artery?
- Superior to instep of foot
What is hypertension defined as?
- BP over 140/90 (Dystolic/Systolic) and is severe if over (180/120)
What happens if hypertension is left untreated? (2)
Usually has no symptoms but can lead do heart disease and stroke
What actions can you do to help lower BP? (5)
Healthy diet (less Na), quit smoking, manage stress, exercise, medications
What is shock and what does it lead to?
Inadequate CO resulting in cardiovascular system not able to meet metabolic demands of body’s cells (hypotension)
What are the types of shock? (5)
- Neurogenic (psychological — trauma)
- Hypovolemic (low blood volume — hemorrhage)
- Cardiogenic (cardiac dysfunction — myocardial infarction)
- Obstructive (blood vessel blockages — blood clots)
- Vascular (blood vessel disorders — vasoconstriction)
- New Hampshire Can’t Outlaw Vampires (kinda stupid but it’s what i just thought of)
What are the signs/symptoms of shock? (8)
Clammy/cool skin, tachycardia, weak/rapid pulse, sweating, hypotension, altered mental status, less urinary output, thirst
What are the homeostatic responses to shock? (4)
- Activation of renin-angiotensin-aldosterone system (increases H2O reabsorption and increases blood volume — higher BP)
- Secretion of antidiuretic hormone (causes vessel constriction — higher BP)
- Activation of sympathetic division of the autonomic nervous system (increases HR — higher BP)
- Release of local vasodilators (opens vessels back up)
What is systemic circulation?
Blood flow within body and the exchange of nutrients/gases between capillaries and tissue
What is pulmonary circulation?
Blood circulating in lungs and the exchange of nutrients/gases between the pulmonary capillaries and alveoli
What is hepatic portal circulation?
- Portal vein drains almost all blood from GI tract and empties into liver
- Hepatic vein picks up filtered blood from liver and drains it back into the inferior VC
What vessels branch off the aortic arch? (3)
Brachiocephalic trunk, LT common carotid artery, LT subclavian artery
Where does the brachiocephalic trunk feed into?
RT head and arm
The LT common carotid artery splits into…?
External and internal carotid arteries (feeds blood to LT side of head)
The brachiocephalic trunk splits into…?
RT common carotid artery (has external + internal carotid arteries), RT subclavian
The descending aorta is also called?
The thoracic aorta and then the abdominal aorta
At the pelvis, the aorta splits to form…?
LT and RT common iliac arteries
The subclavian artery becomes the […] as it descends into the armpit
Axillary artery
The […] artery continues down the medial aspect of the humerus
- Brachial
What arteries does the brachial artery split into?
Radial, ulnar arteries
What blood vessel do you work with when taking blood pressure?
Brachial artery
The […] branches to form the common interosseous artery
Ulnar
The ulnar branches to form the […] artery
Interosseous
The radial and ulnar join and form the […]?
Deep and superficial palmar arches
What do the radial and ulnar arteries branch into? (4)
- Superficial, middle, and deep palmar arches
- Digital arteries
The descending aorta branches into the…?
Posterior intercostal arteries
The internal thoracic artery branches into the…?
- Anterior intercostal arteries
The internal thoracic artery is a branch off the…?
Subclavian
What arteries branch from the subclavian arteries and ascend medially?
The vertebral arteries
The LT and RT vertebral arteries merge to form what artery?
Basilar artery
The common carotid arteries split to form what arteries?
Internal and external arteries
The external carotid arteries supply…?
- The head (except for brain and orbits)
Branches of the external carotid artery include? (2)
Maxillary and facial artery
The internal carotid supply blood to? (2)
The orbits (via the ophthalmic artery) and brain
What arteries are the circle of Willis formed of? (3)
Anterior communicating, RT posterior communicating, LT posterior communicating artery
The circle of Willis is fed by? (2)
Internal carotid arteries and vertebral arteries via the basilar artery
What is the largest branch and 2nd terminal branch of the internal carotid artery?
Middle cerebral artery
What are the three major, unpaired arteries branching off to the left of the abdominal aorta?
- Celiac trunk (most superior)
- Superior mesenteric artery (middle)
- Inferior mesenteric artery (most inferior)
What are the branches of the celiac trunk? (3)
- Common hepatic artery
- Splenic artery
- LT gastric arteries
Where does the celiac trunk provide blood to?
- Upper gastrointestinal system
The superior mesenteric artery supplies blood to…? (2)
Small intestine, most of large intestine (think the top parts)
What is the mesentery?
Membrane that holds intestine in place (or it will drop down) and it has arteries on it that supplies intestine
The inferior mesenteric artery supplies blood to…?
- Distal portion of large intestine
The ileocolic artery supplies blood to…? (3)
- Distal ileum, cecum, and proximal ascending colon
What are the smaller branches of the abdominal aorta? (2)
- Renal and gonadal arteries
What is the gonadal artery?
Provides blood to the gonads
At level L4, the abdominal aorta divides into the LT and RT…
- Common iliac arteries
The external iliac arteries passes under the […] ligament and becomes the [……] artery
- Inguinal, femoral
Each common iliac artery divides into…
An external and internal iliac artery
The internal iliac artery supplies…
- Walls and organs of pelvis
The external iliac artery supplies…
- Lower limbs
As it enters the thigh, the external iliac artery becomes which artery?
- Femoral artery
Branches of the femoral artery include…? (4)
Popliteal artery, anterior and posterior tibial arteries, and fibular artery
When the femoral artery enters the popliteal fossa, it becomes the…?
Popliteal artery
The popliteal artery divides into the…? (2)
Anterior tibial artery, posterior tibial artery
The anterior tibial artery branches into the…?
Dorsalis pedis artery (you can feel pulse on foot dorsum)
What artery is the source of the pulse on your inner malleolus (bump on ankle)?
Posterior tibial artery
