Chapter 13: circulation Flashcards
Name the three layers of an artery or vein
- Tunica intima
- tunica media
- tunica externa
Tunica intima
made of and function
Made of:
- endothelium and underlying connective tissue
Function:
- provides a barrier keeping blood in the blood vessel.
- layer closest to the blood
Tunica media
- made of and function
Made of:
- sheets smooth muscle surrounded by loose connective tissue
Function:
- smooth muscle contracts to increase blood vessel diameter and relaxes to decrease blood vessel diameter
Tunica externa
Made of:
- sheath of connective tissue around the blood vessel
Function:
- stabilizes blood vessel and anchors it in place
name three types of arteries
Elastic
muscular
arterioles
Elastic arteries
they are large and can stretch to accommodate the large pressure changes of the cardiac cycle
Muscular arteries
delivers blood to skeletal muscles and internal organs
Arterioles
SMALL arteries
- deliver blood to capillaries
which is the only blood vessel that allows nutients and waste to exchange across its walls?
capillaries
Why are capillaries the only blood vessel that allows nutrients and waste to exchange across its walls?
they are very thin and only have one layer of endothelium attached to a basement membrane.
- This means that things can easily diffuse through its walls
Why do some capillaries carry blood and others do not at any given moment
Capillaries does not change its diameter to regulate blood flow, instead they work together in a network.
- PRECAPILLARY SPHINCTERS are circular bands of smooth muscle that control how much blood can get into each capillary.
- they can even completely close off a capillary
name the 3 types of capillaries
continuous
Fenestrated
Discontinuous
Continuous Capillary
really tight endothelial cell in the lining so only small things like water and ions can diffuse through
Fenestrated capillaries
So much nutrient/waste exchange happens that the capillary has pores (fenestrations) built into the wall to make diffusion easier.
what affects blood flow
- pressure changes
- resistance
- diameter and length of vessel
- viscosity
how do pressure changes affect blood flow?
increases the amount of blood flow
-
how des the diameter of a vessel affect blood flow
smaller diameter= lower blood flow
larger diameter= high blood flow
how does the length of a vessel affect blood flow
the longer the vessel the more resistance the less blood flow
how does viscosity affect blood flow
More thickness=more resistance=less blood flow
how does resistance affect blood flow
decreases blood flow
- increases blood pressure
what is viscosity
the thickness of blood
Mean Systemic Arterial Pressure (MSAP) equation
MSAP= Diastolic pressure (DP) + 1/3*Pulse pressure(PP)
pulse pressure equation
PP=systolic pressure (SP) - Diastolic pressure (DP)
What is circulatory shock?
when the blood pressure gets so low that the circulatory system can’t adequately deliver blood to tissues and cells stop working right and start hurting and dying
What is hypovolemic shock and how do you fix it
not enough blood volume (usually because you are bleeding to death)
Diastolic pressure VERY low
Cardiogenic shock
Heart can’t pump enough blood to meet the body’s needs
Neurogenic shock
When the CNS gets damaged and the heart does not get the signals it needs to pump out enough blood.
Endotoxic (septic) shock
- a pathogen/infection reaches the bloodstream
- when blood enters tissues blood from capillaries rush to fight the pathogen and causes blood pressure to drop
Anaphylactic shock
When the body reacts to an allergen by initiating the same mechanisms that cause septic shock
Subclavian arteries
carry blood to the arms, chest wall, shoulders, back, and central nervous system
Carotid arteries
carry blood to the head and neck
phrenic arteries
deliver blood to the diaphram
phrenic arteries
deliver blood to the diaphragm
The superior mesenteric artery
delivers blood to the pancreas, small intestine, and most of the large intestine
Inferior mesenteric artery
delivers blood to the last portion of the large intestine and rectum
renal arteries
carry blood to the kidneys
gonadal arteries
carry blood to the gonads
common iliac arteries
deliver blood to the pelvis and lower limbs
posterior intercostal arteries
deliver blood to the spaces between the ribs
lumbar arteries
deliver blood to the lumbar spinal cord and abdominal wall
median sacral artery
delivers blood to the lumbar vertebrae, sacrum, and coccyx
superior vena cava
head and neck, upper limbs, shoulders, and chest
brachiocephalic vein
upper limbs, head and neck
subclavian veins
upper limbs
internal jugular veins
cranium, face and neck
azygos vein
posterior thoracic and abdominal cavities.
It’s an alternate route back to the right atrium if the SVC or IVC gets blocked.
inferior vena cava
most organs below the diaphragm
hepatic veins
liver
renal veins
kidneys
Gonadal veins
the gonads
common iliac veins
pelvic and lwer limbs
common iliac veins
pelvic and lower limbs
lumbar veins
the lumbar spinal cord and abdominal wall
hepatic portal vein
the gastrointestinal tract (to the liver)
Hepatic Vein
drains from the liver
Great saphenous vein
dorsal surface of feet
Great saphenous vein
dorsal surface of feet
2 factors that require modification in the CVS for fetal existence
- Digestive and respiratory systems are not working so there is no need to send blood there
- fetus getting all nutrients from the placenta( organ that brings mother and fetal circulation close together wo nutrient/waste exchange can happen
Umbilical vein
carries oxygenated blood to the placenta
umbilical arteries
carries deoxygenated blood to the placenta
ductus arteriosus
connects the pulmonary tract to the aorta, acting as a second way to bypass the pulmonary circulation
foramen ovale of the heart
allows blood to skip the pulmonary tract and go straight from the right atrium to the left atrium. There is a flap that acts like a heart valve and prevents backflow from the left atrium to the right atrium.
ductus venosus
collects blood from the umbilical vein and veins of the liver and dumps it into the IVC
changes in fetal circulation at birth
When a baby takes its first breath, the lungs and pulmonary vessels inflate. This tells the smooth muscle in the ductus arteriosus to constrict, shutting it off.
- As blood flows through the pulmonary circulation, the pressure in the left atrium rises, shutting the flap in the foramen ovale permanently.
- At room temperature, in about 3 minutes the umbilical cord will close, both by expansion and collapse of some supporting structures and by vasoconstriction of the blood vessels.
list three avascular parts of the body
cartilage
corneas
epidermis
how does cartilage get nutrients
Nutrients diffuse from the perichondrium through the cartilaginous matrix to the chondrocytes.
how does the epidermis get nutrients
from the dermis
how do the corneas get nutrients
from lacrimation (tears)
