3. Physiology I - Fluid Regulation and Perfusion system Flashcards
3 Parts of the CARDIOVASCULAR SYSTEM
- HEART (PUMP) at centre
- BLOOD VESSELS
- FLUID (blood and body fluids)
what are the 3 FUNCTIONS of the CARDIOVASCULAR SYSTEM
- CIRCULATE BLOOD to CELLS and TISSUES
- DELIVERY O2 and NUTRIENTS
- CARRY AWAY METABOLIC WASTE products
as HEART CONTRACTS how does DEOXYGENATED BLOOD travel to the LUNGS for oxygenation (PULMONARY CIRCUIT)
through PULMONARY SEMILUNAR VALVE to the PULMONARY TRUNK
how is OXYGENATED BLOOD returned to the HEART from the LUNGS (pulmonary circuit)
through 4 PULMONARY VEINS to the Left Atrium
in SYSTEMIC CIRCUIT how does OXYGENATED BLOOD leave the HEART as it CONTRACTS (SYSTOLE)
through the AORTIC SEMILUNAR VALVE to the AORTA
though branching arteries and arterioles to capillaries (at tissues)
DEOXYGENATED BLOOD goes from CAPILLARIES to…
VENULES and to VEINS
(to VENA CAVA back to right atrium of heart)
how much of BLOOD FLOW goes to the LUNGS
100%
besides lungs, which major ORGAN receives the MOST BLOOD FLOW and at what %
KIDNEYS - 22%
how much of BLOOD FLOWS to the BRAIN
14%
21% of BLOOD FLOW goes to the…
GI SYSTEM and SPLEEN
which BLOOD VESSEL has the SMALLEST LUMEN DIAMETER and THINNEST WALLS
CAPILLARY
- 5μm lumen diameter
- 1μm wall thickness
LUMEN DIAMETER of CAPILLARY
5μm
WALL THICKNESS of CAPILLARY
1μm
besides capillary, what also have THIN WALLS
VENULES - 2μm
why is FLUID BALANCE ESSENTIAL
to ensure sufficient and efficient MOVEMENT of ELECTROLYTES, NUTRIENTS, GASES through the body’s cells
what can happen when FLUID LEVELS are NOT BALANCED
DEHYDRATION or HYPERHYDRATION
(affect BP)
How does DEHYDRATION (EXCESSIVE LOSS of BODY FLUID) affect BLOOD TONICITY, VOLUME and BLOOD PRESSURE
- as INCREASES BLOOD TONICITY (conc. substances in blood)
- DECREASES BLOOD VOLUME
therefore DECREASES BLOOD PRESSURE
how does HYPERHYDRATION (GAIN in BODY FLUID) affect BLOOD TONICITY, VOLUME and BLOOD PRESSURE
- DECREASES BLOOD TONICITY
- INCREASES BLOOD VOLUME
therefore INCREASES BLOOD PRESSURE
CHANGE in blood TONICITY (conc. solutes) and VOLUME is DETECTED By…
- KIDNEYS
- OSMORECEPTORS in the HYPOTHALAMUS
(detect changes in dilution of blood - osmolarity - and regulate secretion of ADH from pituitary)
PLASMA makes up how much of BLOOD
60%
- WATER, SALTS, PLASMA PROTEINS
40% of BLOOD consists of
CELLS
- ERYTHROCYTES, LEUKOCYTES, PLATELETS
what are found in the WALLS of ARTERIES and VEINS
SMOOTH MUSCLE (thicker in artery) and ELASTIC
how are CAPILLARY WALLS
1 CELL THICK
- INTERLOCKING CELLS
Materials LEAVE CAPILLARIES by which 3 MECHANISMS
- DIFFUSION
- HYDROSTATIC PRESSURE
- PINOCYTOSIS (the cell membrane folds and creates small pockets and captures the cellular fluid and dissolved substances)
WHERE in the body has CAPILLARIES with CONTINUOUS WALLS - continuous endothelial lining and basement membrane
in BLOOD BRAIN BARRIER,
DERMIS (SKIN),
HEART
CONTINUOUS CAPILLARIES are supported by..
PERICYTES
- wrap around the single layer of endothelial cells)
CONTINUOUS CAPILLARIES have structures for controlling… across the wall
PERMEABILITY
where are FENESTRATED CAPILLARIES found
KIDNEYS
what do FENESTRATED CAPILLARIES allow
more efficient FLUID EXCHANGE as they are
10x MORE PERMEABLE
where might you find DICONTINUOUS CAPILLARIES
LIVER, SPLEEN, BONE MARROW
what do DISCONTINUOUS CAPILLARIES allow
BLOOD CELL TRANSFER
VASCULAR system possesses different MECHANISMS for PROMOTING CONTINUOUS FLOW of BLOOD to the CAPILLARIES
these are:
- ELASTIC RECOIL
- SMOOTH MUSCLE REGULATION of DIAMETER of vessels
- SPHINCTERS/VALVES to allow flow in 1 direction
where is MOST of the BLOOD sitting (act as Blood Resevoir)
VEINS and VENULES of the SYSTEMIC CIRCUIT
- thinner walls, flaccid, less muscular and elastic tissue
PERFUSION is the…
CIRCULATION of BLOOD within an ORGAN or TISSUE to MEET the CELL’S NEEDS for OXYGEN, NUTRIENTS, WASTE REMOVAL
all organs dependent on adequate perfusion to function properly
(otherwise can die)
CAPILLARY WALLS are IMPERMEABLE TO:
(don’t allow to pass out)
PROTEINS and BLOOD CELLS
(permeable to gases, ions, water, nutrients, vitamins, hormones)
what do CAPILLARY WALLS have that help PERFUSION (blood moving out)
- INTERCELLULAR CLEFTS / SLITS
- FENESTRATIONS (with PORES)
also have small diameter, and 1 cell thick lining
2 MECHANISMS of CAPILLARY EXCHANGE
- SIMPLE DIFFUSION down conc. gradient
- FILTRATION from plasma out / ABSORPTION back into plasma
FILTRATION and REABSORPTION at CAPILLARY is DETERMINED by which PRESSURES
- Capillary HYDROSTATIC PRESSURE (CHP)
pressure exerted by the blood against the capillary wall, which drives fluid OUT - BLOOD COLLOIDAL OSMOTIC PRESSURE (BCOP)
pressure created by the conc. of Colloidal Proteins in the blood
NET FILTRATION PRESSURE (NFP) =
CHP - BCOP
capillary hydrostatic pressure - blood colloidal osmotic pressure
how are PRESSURES during FILTRATION at the ARTERIAL END (Fluid OUT of capillary)
CAPILLARY HYDROSTATIC PRESSURE > BLOOD COLLOIDAL OSMOTIC PRESSURE
CHP (35) GREATER than BCOP (25)
NFP = +10 mm Hg
how are PRESSURES during REABSORPTION at the VENOUS END (Fluid BACK INTO capillary)
CHP < BCOP
capillary hydrostatic pressure (18) is LESS than Blood colloidal osmotic pressure (25)
NFP = -7 mm Hg
NFP at ARTERIAL END
+10 mm Hg
NFP at VENOUS END
-7 mm Hg
NFP MID CAPILLARY
0 mm Hg
(CHP = BCOP)
FUNCTIONS of LYMPHATIC SYSTEM (lymphatic capillaries)
- DRAIN EXCESS FLUID FROM TISSUES (as more fluid filtered out than reabsorbed)
- TRANSPORT CLEAN FLUIDS BACK INTO BLOOD
- REMOVES ‘DEBRIS’ from CELLS (immune function)
- TRANSPORTS FATS from DIGESTIVE SYSTEM (chylomicrons)
what is necessary in MAINTAINING ADEQUATE PERFUSION
BLOOD VOLUME
what happens when a TISSUE LOSES its BLOOD SUPPLY
ISCHEMIA which may lead to tissue death, INFARCT after some time
which SYSTEM is responsible for REGULATING BLOOD VOLUME
RENAL system: RENIN-ANGIOTENSIN ANGIOTENSINOGEN SYSTEM (RAAS)
(aka renin-angiotensin system, RAS)
what does KIDNEY do if BLOOD VOLUME is LOW
MORE REABSORPTION
what does KIDNEY do if BLOOD VOLUME is LOW
MORE REABSORPTION of filtrate
when is RENIN RELEASED from the JUXTAGLOMERULAR CELLS
when there is a DROP in BLOOD PRESSURE
and DROP in FLUID VOLUME
- sensed by MACULA DENSA cells
how do we get ANGIOTENSIN I in RAAS
RENIN CLEAVES ANGIOTENSINOGEN from liver
MACULA DENSE CELLS SENSE…
NaCl CONC. and FLOW
- decreased NaCl or flow causes release renin
ANGIOTENSIN II acts on which RECEPTORS
AT1 RECEPTORS (G-protein coupled)
ACTIONS of ANGIOTENSIN II
- VASOCONSTRICTION of blood vessels to increase vascular resistance and INCREASE BP
- stimulates RELEASE ALDOSTERONE from ADRENAL CORTEX which acts on KIDENYS to INCREASE Na+ and H2O RETENTION/REABSORPTION (INCREASE blood VOLUME and BP)
- stimulates release of VASOPRESSIN / ADH from posterior PITUITARY which acts on KIDNEYS to INCREASE REABSORPTION / RETENTION of H2O (INCREASE blood VOLUME and BP)
- stimulates NORADRENALINE RELEASE and INHIBITS UPTAKE from nerve endings, enhancing SYMPATHETIC ADRENERGIC FUNCTION
- stimulates CARDIAC and VASCULAR HYPERTROPHY (muscle growth in vascular system over time)
ANGIOTENSIN II stimulates the RELEASE of which HORMONES
- ALDOSTERONE (adrenal cortex)
- ADH / VASOPRESSIN (posterior pituitary)
- NORADRENALINE (adrenal medulla)
what BINDS to G-PROTEIN COUPLES RECEPTORS
ANGIOTENSIN II (AT1 RECEPTORS)
ANGIOTENSIN II stimulates … and … HYPERTROPHY
CARDIAC and VASCULAR
