cardiovascular system #2

week 7

structure, location, function of arteries

structure:

• thick walls, lumens,

• tunica intimate: rippled bc of vessel constriction internal elastic membrane present

location: alongside veins & nerves, deep

function : carry O2 rich blood from heart to tissue, except pulmonary artery

structure, location, function of veins

structure: tin walls, vales to prevent back flow, more collapsable

location: closer to surface

function return of O2 depleted blood to heart, except pulmonary vein

tunica layers, vales, direction blood flow, pressure and relative O2 concentration in arteries vs veins

Arteries:

* Tunica intima: Rippled, internal elastic membrane present.

* Tunica media: Thick, smooth muscle & elastic fibers.

* Tunica externa: Thinner than media, collagen & elastic fibers.

* Blood flow: Away from heart.

* Pressure: High.

* O2 concentration: High (systemic), Low (pulmonary).

Veins:

* Tunica intima: Smooth, no internal elastic membrane.

* Tunica media: Thin, smooth muscle & collagen fibers.

* Tunica externa: Thickest layer, collagen, elastic fibers, smooth muscle.

* Blood flow: Towards heart.

* Pressure: Low.

* O2 concentration: Low (systemic), High (pulmonary).

structure, location, function of capillaries

structure: extremely thin walls, single layer endothelial cells

location: through all tissues - capillary beds

function: sites of nutrients, waste exchange b/w blood and tissues

structure, function of arterioles

structure: smaller branches or arteries, SM to regulate blood flow & pressure

function: control blood flow to capillary bed & help regulate blood pressure through constriction & dilation

structure, location, function of venules

structure: sml vessels that converge from capillaries & have thinner walls than veins

location: found b/w capillaries & veins, often grouped in tissue areas requiring extensive drainage

function: collect blood from capillaries & transport to larger veins

how vasoconstriction effects blood flow

• SM in vessels contract

• decrease vessel diametre

• a smaller vessel diameter increases resistance to blood flow

• = blood pressure, hear has to work harder

how vasodilation effects blood flow

• SM relaz

• increase diametre

• larger vessel = decrease resistance to blood flow

• decrease blood pressure

describe direction pf blood flow through body

1. lungs

2. heart

3. arteries

4. arterioles

5. capillary bed

6. venules

7. veins

8. heart

9. lungs

3 steps of generation of pressure by ventricular contraction

1. ventricular contration (systole)

2. pressure build up

3. ejection of blood

describe ventricular contration (systole)

• ventricles contact after electrical signal from SA side and AV node

• trigger myocardium to contract

describe pressure build up

• contraction decrease vessel volume

• increase BP = closed AV vales to prevent back flow to atria

describe ejection of blood

• once ventricular pressure exceeds the pressure in arteries, semilunar valves open = blood eject into circulatory system

define total peripheral resistance

• overall resistance to blood flow in systemic blood vessels , excluding pulmonary System

explain 3 major factors that affect resistance to blood flow

• vessel diametre

• blood vessel length: longer increases resistance (more SA)

• blood viscosity: increase viscosity increase resistance, influenced by dehydration

pulmonary vs systemic circuits

pulmonary circuits:

• resistance lower

• shorter, thin walls

• allow blood flow though easily

systemic circuts:

• resistance higher

• longer & need distribute blood whole body

define CO, SV & HR

CO= cardiac output: total volume pumped by heart per min

• CO= SVx HR

SV= stroke volume: amount of blood ejected by ventricle with each heartbeat

HR= heart rate: heart beats per min

explain systolic pressure

max pressure during ventricular contraction

• reflects force pushing blood through arteries

explain diastolic pressure

min pressure during ventricular relaxation

• indicates how well vessels maintain pressure b/w beats

describe mean arterial pressure (MAP)

avg pressure in arteries

• MAP= 1/3 systole + 2/3 diastolic

• represents pressure needed for blood to flow effectively

capillary physiology and anatomy

• smallest blood vessel

• most permeable tissue

• only blood vessel those walls permit & surrounding interstitial fluid

why isn’t all fluid reabsorbed for capillary & lymphatic system

• capillary filtration exceeds reabsorption

• lymphatic system collects ducts excess interstitial fluid & returns to blood stream

what are the surrounding capillary interstitial fluid

• HPc: capillary hydrostate pressure

• OPc: capillary colloid pressure

• HPif: interstitial fluid hydrostatic pressure

• OPif: intersitual fluid colloid osmotic pressure

explain effect of SNS on heart& blood vessels and PNS on heart

SNS:

• increase HR (tachycardia)

• increase contractibility (strength heart contraction)

• increase SV & CO

• vasoconstriction, increase BP

PNS

• decrease HR (bradycardia)

• decrease CO= increase relax & energy conservation

explain role of baroreceptors in short term maintenance of BP homeostasis

• specialised pressure sensors in carotid sinus & aortic arch

  1. detect changes in BP through stretching of vessel walls

  2. send signals to brain stem cells(vagus nerve)

  3. trigger corrective response to stabilise BP

     • increase BP - activate PNS (vasodilation)

     • decrease BP - activate SNS (vasoconstriction)

list reasons why its important to maintain BP

• ensures adequate O2 and nutrient delivery to tissues

• maintain proper organ production

• prevents complications (stroke, heart attack)

• supports efficient waste removal from cells

• balances fluid distribution within body

describe structure & components of blood

blood: specialised fluid CT that contains forced elements

suspend in fluid matric (plasma)

name forced components (blood cells, platelets) of blood and their functions

• RBC: transport O2 from lungs to tissues & carry CO2 back to lungs for exhalation

• WBC: protect body against infections

  granulocytes:

• neutrophil: bacteria killers

• eosinophil: digestive enzymes

• basophil: contain histamine = vasoconstriction

• granulocytes: monocytes: transform to macrophages, lymphocytes: B- produce anti-bodies, T-attack infected cells

role of haemoglobin

• heme contain Fe2+ = bind to O2

• haemoglobin bind to CO2, global that bind it

oxyhemoglobin vs deoxyhemoglobin

oxyhemoglobin

• bound with O2

deoxyhemoglobin

• w/o O2, after O2 diffuses into tissues

explain ABO system

based around antigens

A blood= A antigen

B blood = B antigen

AB blood = A&B antigen

O blood = no antigen

antibodies:

A blood= B antibodies

B blood = A antibodies

AB blood = none

O blood = A & B antibodies

explain rhesus factor

• presence of Rh antigen on RBC indicate Rh+

• not preformed

• 2nd reaction causes typical transfusion reaction

describe haemostats (blood clotting)

3 steps :

1. vascular spasm: blood vessel damaged SM in vessel wall constricts (vascular spasm), decrease blood flow to injured area

2. platelet plug formation: platelets attracted to exposed collagen in damaged area, activate release chemical mediators, form temporary platelet plug

3. coagulation: blood transforms from liquid to gel, reinforce plug, intrinsic/extrinsic, both converge to common pathway

describe 2 steps in clot removal

1. retraction

   • platelets contract and pull clot together

   • edges of vessel together

2. repair

   • platelet derived growth factor stimulate rebuilding of blood vessel walls

   • fibroblasts from CT patch

   • stimulated by vascular endothelial growth factor

   • endothelial cells multiply & restore lining