Biology 12 - Circulatory System

Anatomy and Physiology 12 - Samra

Functions of Blood

1. Transport oxygen and nutrients
2. protect body against microbials (wbcs and antibodies)
3. prevent blood loss by cotting
4. regulate body temperature

Composition of blood

~5L which is 9% of body mass
losing half is fatal

Parts of Blood

1. liquid plasma
2. RBCs (erythrocyte)
3. WBC (leukocyte)
4. platelets (thrombocyte)

Plasma

straw coloured

plasma proteins

albumins

albumins

primary binding and transport protein

globulins

lipoproteins - transport cholestrol and triglycerides as chylomicrons
immunoglobulins - antibodies that fight infections

fibrinogens

necessary for blood clotting

red blood cells (erythrocytes)

biconcave discs 7-8µm

hemoglobin

red pigment

white blood cells (leukocytes)

irregular shaped nuclei

granular leukocytes

more granules than agranular leukocytes

agranular leukocytes

fewer granules (various enzymes + antibiotic like proteins) spherical or kidney-shaped nucleus

platelets (thrombocytes)

fragments of larger cell

blood clotting (coagulation)

platelets clump at site of puncture and partially seal the leak = plug
12 clotting factors

blood vessels

1. arteries
2. arterioles
3. capillaries
4. venules
5. veins

arteries

AWAY from heart

arterioles

small arteries just visible to naked eye

capillaries

smallest most numerous

venules

tiny vessels that drain blood from capillaries then join to form veins

veins

back to heart

heart

four chambers

left side of heart

oxygenated blood

right side of heart

deoxygenated blood

cardiac cycle

roughly 70 bpm

diastole

blood flow into four chambers

systole

atria contraction = brief 0.1 sec

nodal tissue

heart tissue with both muscular and nervous characteristics

medulla oblongata

heart rate centre which can slow down and speed up heart rate

epinephrine

hormone secreted from adrenal gland when stressed

electrocardiogram

indicated conduction of electrical impulses through heart during cardiac cycle

three distinct waves:

1. P wave
2. QRS wave
3. T wave

P wave

occurs as atria contracts (first part of systole)

QRS wave

occurs as ventricles contract (second part of systole)

T wave

occurs when ventricles repolarize (diastole)

blood pressure

pressure of blood against wall of blood vessel

bp levels in blood vessels

arteries > arterioles > capillaries > venules > veins

systolic bp

highest arterial pressure

diastolic bp

lowest arterial pressure

normal bp

120/80

hypotension

low bp

hypertension

high bp

causes of bp disorders

1. hereditary
2. smoking
3. obesity
4. high salt intake
5. stress
6. high fat diet

pathways of circulation

1. pulmonary circulation
2. systemic circulation

pulmonary circulation

right atrium -> right ventricle -> pulmonary trunk -> pulmonary arteries (2) -> pulmonary arterioles -> pulmonary capillaries -> lungs -> pulmonary venules -> pulmonary veins (2) -> left atrium -> left ventricle

systemic circulation

pulmonary circulation -> aorta (up) -> carotid artery -> head and arms -> jugular vein/subclavian vein -> superior vena cava

pulmonary circulation -> aorta (down) -> mesenteric arteries -> digestive tract -> hepatic portal vein -> liver -> hepatic vein -> inferior vena cava

aorta (down) -> renal artery -> kidneys -> renal vein -> inferior vena cava

aorta (down) -> iliac artery -> trunk and legs -> iliac vein -> inferior vena cava

subclavian arteries/veins

carry c/o2 blood to/from superior vena cava/aorta to arms/shoulders

jugular veins

drain co2 from head/neck to subclavian veins

carotid arteries

deliver o2 to head/neck

mesenteric arteries

supply o2 to intestines/gut to liver

anterior/superior vena cava

collects co2 upper body to RIGHT atrium

posterior/inferior vena cava

collects co2 blood lower body to RIGHT atrium

pulmonary veins/arteries

carry c/o2 blood to/from lungs to left/right atrium

hepatic vein

drain co2 from liver to inferior vena cava

hepatic portal vein

drain co2 blood from gut to liver

renal arteries/veins

carry c/o2 blood from/to kidneys

illiac arteries/veins

carry c/o2 blood from/to pelvis and legs

*think illiac = illiac crest = pelvic bone

coronary arteries/veins

carry c/o2 blood to/from heart muscle

placenta

responsible for waste removal and nourishement

foramen ovale (oval opening)

opening between two atria on top of septum

ductus arteriosus (arterial duct)

extra blood vessel which allows blood to pass from pulmonary artery to aorta

umbilical arteries/veins

connects fetus with placenta

ductus venosus (venous duct)

connects umbilical vein to posterior/inferior vena cava to bring blood back to baby's heart

pathway of blood in fetus

all blood in fetus is mixed

right atrium -> oval opening -> left atrium

right atrium -> atrioventicle valve -> right ventricle -> pulmonary artery -> arterial duct -> aorta -> tissue -> umbilical arteries -> placenta -> mother -> umbilical vein -> through liver -> venous duct -> inferior vena cava

lymphatic system main functions

1. drains excess fluid from tissues
2. absorbs fat molecules from small intestine
3. protects body against infections

lymphatic system function 1 - drain excess fluid from tissues

capillary tissue fluid exchange causes fluid to leak from blood into tissue

lymphatic system function 2 - absorbs fat molecules from small intestine

lacteal = blind ends of lymph capillaries in villi of small intestine

lymphatic system function 3 - protects body against infections

lymphoid organs fight infections