Download circulatory

Two major portions : the blood vascular system and the lymphatic
system.
Serves to transport food, water, gases, hormones and waste
materials in the body, defends the body, keeps the organs moist
and equalizes the temperature.
The fluid tissue, blood circulates in blood vessels with help of the
muscular pump, the heart.
(a) Appearance and position – conical, muscular organ,
occupying part of mediastinum (space between two
pleural sacs that enclose the lungs).
(b) Pericardium – enclosed in a two layered sac,
pericardium. Inner layer (visceral pericardium), outer
layer (parietal pericardium). Pericardial cavity – space
between the two layers – contains a watery coelomic
fluid, the pericardial fluid.
(c) External structure – Auriculo – ventricular groove,
Interventricular groove, Interventricular groove.
Auricular appendix.
(d) Internal structure – two halves : right and left.
Each half – two chambers : auricle and ventricle.
Heart of rat – four-chambered. Auriculo-ventricular
aperture. Musculi pectinati (network of low ridges).
Two auricles separated by : interauricular septum (has small
oval depression – fossa ovalis).
Inner surface of ventricles – network of low ridges (columnae
carneae) and musculi papillares.
Two ventricles separated by – interventricular septum.
Right auricle – three large vessels – right and left precavals
and the postcaval.
Valve of Eustachius recieves coronary sinus.
Valve of Thebisius.
Right auriculo-ventricular aperture – guarded by tricuspid
valve.
Left auricle – two blood vessels : right and left pulmonary
veins. Left auriculo-ventricular aperture.
Left ventricle gives – aortic arch.
(e) Histological structure – heart – a modified blood vessel.
Endocardium and myocardium. Straited fibres – have thick
cross bands – intercalated discs.
(f) Working – systole and diastole.
Longitudinal
section of
the heart of
rat
Mechanism of heart beat
(g) Circulation – aerated and non-aerated blood remain
reparate. Blood passes- first through right, then left (double
circulation). Pulmonary circulation (right ventricle to left
auricle via lungs). Systemic circulation (left ventricle to right
ventricle via body).
(h) Efficiency
(i) Control of heart beat
Two types : arteries and veins.
The arterial system of rat
Aortic system and pulmonary system.
1. Aortic System – includes aortic arch and its branches.
Arch rises from right anterior towards left, then runs
backward as dorsal aorta along mid-dorsal line.
1. Coronary arteries – supply blood to wall of heart.
2. Innominate artery –
(i) Right common carotid artery – supplies blood to right side
of brain.
(ii) Right subclavian artery – (a-right mammary artery –
supplies blood to mammary glands & b-brachial artery –
supplies blood to right forearm.
3. Left common carotid artery – supplies blood to left side of
head.
4. Left subclavian artery – supplies blood to left forearm.
5. Intercostal arteries – supply blood to intercostal muscles.
6. Phrenic arteries – supply blood to diaphragm.
7. Coeliac artery –
(i) hepatic artery – blood to liver.
(ii) gastric artery – blood to stomach.
(iii) Lienal artery – blood to spleen and pancreas.
8. Anterior mesenteric artery – blood to duodenum, ileum, caecum
and colon.
9. Renal arteries – blood to kidneys.
10. Genital arteries – blood to ovaries and Fallopian tubes.
11. ILio-lumbar arteries – blood to abdomen.
12. Posterior mesenteric artery – blood to hind part of colon and
rectum.
13. Common iliac arteries –
(i) internal iliac artery – blood to dorsal pelvic cavity.
(ii) external iliac artery (vesico-uterine artery – blood to
urinary bladder and uterine artery and posterior Epigastric
artery – blood to ventral abdomen).
(iii) femoral artery – blood to hind-limb.
14. Sacral or caudal artery – blood to tail.
15. Lumbar arteries – carry blood to lung.
B. Pulmonary system – includes pulmonary arch
(bifurcates into right and left pulmonary arteries in the left
auricle). Ligamentum arteriosum (connects aortic &
pulmonary arches). Ductus arteriosus – passage between the
two vessels in embryo.
The venous system of rat
Four divisions : venae cavae system, portal system, pulmonary
system and coronary system.
A. System of venae cavae – includes three vessels :
1. Left Anterior Vena Cava – recieves 6 veins (internal
jugular, external jugular – blood from face & ear,
subclavian - blood from forelimb & shoulder, mammary –
blood from mammary glands, intercostal – blood from
intercostal muscles & azygos).
2. Right Anterior Vena Cava.
3. Posterior Vena Cava – starts as caudal or sacral vein,
recieves veins (common iliac veins – femoral vein’ vesiaco
uterine vein & posterior epigastric vein, ilio lumbar veins,
genital veins, renal veins, hepatic veins).
B. Portal System – in rat, hepatic portal system,
includes single large vein – hepatic portal vein.
Recieves 4 tributaries:
1. Lieno-gastric vein – collects blood from stomach & spleen.
2. Duodenal vein – blood from duodenum & pancreas.
3. Anterior mesentric vein – blood from ileum, caecum, colon
& rectum.
4. Posterior mesentric vein – blood from rectum.
• Brings digested food with blood to liver.
• Liver stores sugar for future use.
• Deaminates excess proteins.
A. Structure – fluid tissue, forms 6-10 % of body weight,
opaque, sticky, salty & a mild alkaline reaction, pH about
7.4, osmotic pressure – 7 atmospheres, bright red
(oxygenated), purple (deoxygenated), contains plasma
(contains corpulses – red, white & platelets).
(a) Plasma – faint yellow liquid, 90% of it is water,
contains inorganic salts and blood proteins.
The salts include chlorides, carbonates, sulphates &
phosphates.
Other things dissolved : food, waste products, gases,
hormones, vitamins, enzymes & antibodies.
Hydrostatic pressure – pressure forcing substances into
tissue fluid.
Hydrostatic pressure – highest at arterial end, Osmotic
pressure – highest at venous end.
(b) Red Corpulses – circular, biconcave, denucleated discs,
bounded by elastic plasma membrane, have homologous
cytoplasm.
Cytoplasm contains haemoglobin and inorganic ions, impart
red colour to blood.
Rouleaux – piles of red corpulses.
(c) White corpulses – irregular shape , colourless, nucleated.
Diapedesis – red corpulses passing out of capillaries.
2 main types : non-granular leucocytes (monocytes,
lymphocytes) & granular leucocytes (basophils, eosinophils,
neutrophils).
(d) Blood Platelets – rounded or oval, non-nucleated,
granular, destroyed by phagocytosis in blood, aid in blood
clotting.
Haemopoiesis – formation of new blood corpulses.
(i) Plasma – takes digested food from intestine to body, collects CO2
from tissues & brings it to lungs, carries urea from liver to
kidneys, transports hormones, supplies materials to glands,
regulates water balance, regulates pH of body fluids, equalizes
body temperature, keeps al tissues moist.
(ii) Red corpulses – carry oxygen from lungs to tissues.
(iii) White corpulses – act as soldiers, scavengers & builders of body,
heal wounds.
(iv) Blood platelets – help in blood clotting.
Comprise of lymph, network of fine channels, lymphatic vessels
& lymphatic nodes.
(a) Lymph – two parts : plasma & white corpulses.
Hands over food, oxygen & hormones from blood to tissue
cells, & waste materials from tissue cells to blood.
(b) Lymphatic Capillaries – from intercellular spaces, tissue
fluid passes into lymphatic capillaries.
(c) Lymphatic Vessels – lymphatic capillaries join to form
these vessels, lymphatic vessels join to form – thoracic duct
& right lymphatic duct.
(d) Lymphatic nodes – occur at intervals in course of
lymphatic vessels, rich in white corpulses, remove bacteria
from lymph.
Structure – elongated, curved, dark-red organ attached to
posterior border of stomach by gastro-splenic omentum.
Functions – Macrophages (certain cells of spleen) destroy
worn-out red corpulses & foreign germs, stores, releases &
produces new red and white corpulses.