Anatomy and Physiology 1 Cardiovascular System Topic 4.3: Circulation PDF

Anatomy and Physiology1 Cardiovascular system Topic 4.3...

Anatomy and Physiology1 Cardiovascular system Topic 4.3 :Circulation Prepared by: Madam Leong Yee Leng 1 This Photo by Unknown Author is licensed under CC BY-NC Blood Flow through Blood vessels 2 LEARNING OUTCOME At the end of this lesson, students will be able to: 1. list the main vessels involved in circulation through the lungs; 2. explain the circulation of the blood through the lungs; 3. list the arteries supplying blood to all major body structures; 4. state the venous drainage involved in returning blood to the heart from the body; 5. explain the arrangement of blood vessels relating to the portal circulation. 3  CIRCULATORY SYSTEM The blood flows through two division of circulatory system 1. Pulmonary circulation 2. Systemic circulation 4  CIRCULATORY SYSTEM 1.PULMONARY CIRCULATION Superior and inferior vena cava empty the blood into the right atrium Blood ejected into right ventricle via tricuspid valve Blood is pumped from right ventricle via tricuspid valve to the lungs through pulmonary artery. The exchange of gases occurs between blood and alveoli of the lungs through pulmonary capillary membrane. The oxygenated blood returns to left atrium through the pulmonary veins.  CIRCULATORY SYSTEM Pulmonary circulation Pulmonary arteries enter their respective lungs at the hilum → smaller branches→ capillaries surrounding the alveoli Exchange of gases takes place between capillaries blood and air in the alveoli. D capillaries containing oxygenated blood merge into larger venules→pulmonary veins→left atrium→left ventricle→aorta 6  CIRCULATORY SYSTEM 2. SYSTEMIC CIRCULATION Four pulmonary veins from the lung carry oxygenated blood back to the left atrium The blood which is pumped from left ventricle passes through the mitral valve then into aorta and arterial system and reaches the tissues. The blood vessels of arterial system are aorta, larger arteries, smaller arteries and arterioles. The arterioles branch into the capillaries. The capillaries are responsible for exchange of various substances between blood and the tissues.  CIRCULATORY SYSTEM Systemic circulation The blood which is pumped from left ventricle→aorta around the body→superior and inferior vena cavae→returns into right atrium 8  MAJOR BLOOD VESSELS- AORTA Largest artery Begins at the upper part of the left ventricle Arches backward to the left Descends behind the heart through thoracic cavity a little to the left of thoracic vertebrae At 12th thoracic vertebra it passes behind the diaphragm Then downwards in the abdominal cavity to the level of the 4th lumbar vertebra, devides into right and left iliac arteries. 9  MAJOR BLOOD VESSELS- AORTA The aorta will be describe according to location 1. Thoracic aorta i. Ascending aorta ii. Arch of the aorta iii. Descending aorta 2. Abdominal aorta 10  Aorta Ascending aorta 5cm, short Lies behind sternum Branches right & left coronary artery that supply blood to the myocardium Arch of aorta Curves sharply downwards behind the left side of the heart, in front of the trachea Brachiocephalic artery, left common carotid artery, left subclavian artery Brachiocephalic artery→right common carotid artery, right subclavian artery 11  Aorta Descending aorta Long segment Descends to the diaphragm Begins at 4th thoracic vertebra. Extends downwards in front of the bodies of thoracic vertebrae to 12th thoracic vertebrae, passes behind the diaphragm to become abdominal aorta. Supply blood to walls and organ of thoracic cavity 12  Aorta Abdominal aorta Continuation of the thoracic aorta Start from 12th thoracic vertebra Descends in front of the vertebral column to level of 4th lumbar vertebra→ right & left common iliac arteries Supplying blood to abdominal structures and organs. 13 Circulation in the head and neck Arterial supply to the head and neck 1.Carotid arteries External carotid artery Internal carotid artery 2.Circulus arteriosus 3.Vertebrae arteries 14  CAROTID ARTERY Right common carotid artery - Branches into carotid sinuses & carotid bodies - Walls of carotid sinuses contain numerous nerve endings (baroreceptor) of the glossopharyngeal nerves. - The nerve ending are stimulated by changes in blood pressure in the carotid carotid sinuses. - Carotid bodies are two small groups of chemoreceptors. They are supplied by the glossopharyngeal nerves and are stimulated by changes in the carbon dioxide and oxygen content of blood. - They initiate reflex adjustment of respiration through respiratory centre in medulla oblongata. 15  External carotid artery They supplies the superficial tissue of the head and neck, via number of branches. 1. Superior thyroid artery-supplies the thyroid gland 2. Lingual artery-supplies tongue, membrane lines the mouth, structures in the floor of mouth, tonsil and epiglottis 3. Facial artery-supplies muscle of facial expression and structures in the mouth 4. Occipital artery- supply posterior part of the scalp 5. Temporal artery- supply frontal, temporal and parietal scalp. 6. Maxillary artery- supply muscle of mastication Kunyah 16  Internal carotid artery Major contributor to the circulus arteriosus (circle of Willis) which supplies most of the brain. Branches supply the eyes, forehead and nose. Ascends to the base of the skull and passes through the foramen in the temporal bone. 17 CIRCULUS ARTERIOSUS (CIRCLE OF WILLIS) Supply arterial blood to the brain. FOUR large arteries- 2 internal carotid arteries 2 vertebral arteries Unite to form this complete circular channel lying in the subarachnoid space on the underside of the brain. The arrangement in the circulus arteriosus is such that the brain receives an adequate blood supply contributing artery is damaged and during extreme movement of the head and neck. 18 CIRCULUS ARTERIOSUS (CIRCLE OF WILLIS) The circulus arteriosus is formed by: Two anterior cerebral arteries Two internal carotid arteries One anterior communicating artery Two posterior cerebral arteries One basilar artery 19 CIRCULUS ARTERIOSUS (CIRCLE OF WILLIS) The circulus arteriosus is formed by: Two anterior cerebral arteries- supply anterior part of the of the brain. Two internal carotid arteries –supply the sides of the brain One anterior communicating artery Two posterior cerebral arteries- supply posterior part of the brain One basilar artery- supply parts of the brain stem 20 Circulation in the upper limb  ARTERIAL SUPPLY Right subclavian artery i. Vertebral artery (brain) ii. Internal thoracic artery (breast and thoracic cavity) Axillary artery underarm Brachial artery between radius and una Radial artery 'thumb-1 Ulnar artery spinky- Circulation in the thorax  ARTERIAL SUPPLY Branches of the thoracic aorta supply structures in the chest: Bronchial arteries- supply lung tissues not directly involved in gas exchange Oesophageal arteries- supply the oesophagus, intercostal arteries, intercostal muscle, some muscle of thorax, the ribs, skin and its underlying Circulation in the abdomen  ARTERIAL SUPPLY Branches of the abdominal aorta supply structures in the abdomen Paired branches: i. Phrenic arteries, supplying the diaphragm ii. Renal arteries, supplying the kidneys iii. Suprarenal arteries, supplying the adrenal gland iv. Gonadal arteries, supplying ovaries (female)and testes (Male)  ARTERIAL SUPPLY Unpaired branches: Coeliac artery. Arises immediately below the diaphragm and divides into three branches i. Left gastric artery Stomach ii. Splenic artery supplying the spleen and pancreas iii. Hepatic artery supplying the liver, gall bladder and parts of the stomach, duodenum and pancreas iv. Superior mesenteric artery, supply the entire small intestine and about half the proximal large intestine. v. Inferior mesenteric artery, supplies the distal half of the large intestine and part of rectum. Circulation in the pelvis and lower limb 28  ARTERIAL SUPPLY Common iliac arteries The abdominal aorta divides at 4th lumbar vertebrae into : i. Right common iliac arteries ii. left common iliac arteries iii. Internal iliac arteries, supply organ within pelvic cavity (uterine artery) iv. external iliac arteries, supply blood to the structure of the thigh and some superficial pelvic and inguinal structure Femoral artery Celan Kaki Popliteal artery (supply knee joint) Anterior tibial artery Posterior tibial artery Dorsalis pedis artery Plantar artery 29 Venous supply  VENAE CAVAE (Heart) Superior and inferior vena cavae Largest veins in the body Empty blood directly into the right atrium Superior-drains all body structure lying above the diaphragm Inferior- drains blood from all structures below diaphragm Superior vena cava- formed by union of left and right brachiocephalic veins Inferior vena cava- formed at the level of 5th lumbar vertebra by the union of right left common iliac veins 31 VENOUS RETURN (Head and neck) Venous blood from head and neck is returned by deep and superficial veins. i. External jugular vein- return venous blood from superficial structures of the face and scalp. ii. Dural venous sinuses- venous blood from deep areas of the brain iii. Superior sagittal sinus- carries the venous blood from the superior part of the brain. (frontal region to occipital region) iv. Straight sinus v. Transverse sinus vi. Sigmoid sinuss VENOUS RETURN (Head and Neck) Internal Jugular veins Begin at the jugular foramina in the middle cranial fossa Behind the clavicle they unite with subclavian veins, carrying blood from upper limbs. Superior Vena Cava Drains all the venous blood from head, neck, and upper limbs  VENOUS SUPPLY (Upper limbs) Deep veins ▪ Palmar metacarpal veins ▪ Deep palmar venous arch ▪ Ulnar radial veins ▪ Brachial veins ▪ Axillary veins ▪ Subclavian Vein The superficial veins begin in the hand and consist of the following: Cephalic vein Basilic vein (receives blood from medial aspect of the hand, forearm and arm) Median vein Median cubital vein  VENOUS RETURN (Chest) MC4 Azygos vein & Hemiazygos vein- drain venous blood from the organs Main veins that join them are: Bronchial Oesophageal Intercostal veins Distal end of oesophagus, some oesophageal vein join the azygos vein and others left gastric vein. Vesus plexus is formed by anastomoses between the veins joining the azygos vein and those joining the left gastric veins, linking the general portal circulation.  VENOUS RETURN (Abdomen) Hepatic veins- drain the liver, renal glands Lumbar veins- drain lower abdominal structures Gonadal veins drain the ovaries (female) and testes(male) Hepatic portal vein- blood from digestive organs in the abdomen 36  PORTAL CIRCULATION Venous blood passes from the tissues to the heart by the most direct route through only one capillary bed. In the portal circulation, venous blood from the capillary beds of the abdominal part of the digestive system, the spleen and pancreas travels first to the liver. It passes through a second capillary bed, the hepatic sinusoids Blood with a high concentration of nutrients ,absorbed from the stomach and intestines, goes into the liver first. This supplies liver with rich source of nutrients for its extensive metabolic activities and ensures that the composition of blood leaving alimentary tract can be appropriately regulated. 37  PORTAL CIRCULATION First-pass metabolism- Ensures that unwanted or potentially toxic material such as drugs are eliminated before the blood is return into general circulation. Rectum vein- draining blood from the lower two thirds of the rectum empty into systemic veins not the portal veins, and so this blood travels to the heart without first passing through the liver. Drug from rectal formulations are therefore absorbed directly into the general circulation. 38  PORTAL CIRCULATION Portal vein Splenic veins, drain blood from the spleen, the pancreas and part of the stomach Inferior mesenteric vein , drain venous blood from rectrum, pelvic structures and descending colon of the large intestine. Superior mesenteric vein, returns venous blood from the small intestine and the proximal parts of the large intestine (caecum & Ascending and transverse colon). Gastric veins drain blood from the stomach and distal end of oesophagus. Cystic vein drains venous blood from the gall bladder and joins the portal vein. Hepatic Portal circulation is then returned directly to the inferior vena cava through hepatic veins. 39 40  VENOUS RETURN (Lower limbs) Deep and superficial veins in lower limb Movement of blood towards the heart is partly dependent on contraction of skeletal muscles. Backward flow is prevented by a large number of valves. Superficial veins receive less support from surrounding tissues than deep veins. 41  VENOUS RETURN Superficial vein i. Great Saphenous vein (longest vein in the body) ii. Small sapheneous vein (drain dorsum of the foot join together) 42 Brain exercise 1. Name 3 sections of the aorta. 2. What is the key feature of the hepatic portal circulation? 43 FETAL CIRCULATION 44 LEARNING OUTCOME At the end of this session, students will be able: 1. State the functions of placenta 2. Describe the fetal circulation 3. Explain blood flow through the heart, lungs and liver before and shortly after birth McP 45  FEATURES OF THE FETAL CIRCULATION Fetus obtains its oxygen and nutrients and excretes its waste, via the mother’s circulation. Placenta is a temporary structure that provides an interface between mother and fetus, and allows the exchange of substances between their circulatory systems. Placenta develops from the surface of the fertilised ovum embedded into the maternal uterine endometrium. It is expelled from the uterus during the final stage of labour soon after birth. This Photo by Unknown Author is licensed under CC BY 46  FEATURES OF THE FETAL CIRCULATION Structure Mature placenta –pancake-shaped 500gm, has diameter of 20cm 2.5cm thick Placenta firmly attached to the uterine wall Extensive network of fetal capillaries bath in maternal blood Branches of uterine artery bring maternal blood (500ml/min) into chambers in the placenta called intervillous spaces. Oxygen and nutrients diffuse or actively transported into fetal blood from the maternal blood, and fetal wastes diffuse into mother’s This Photo by Unknown Author is licensed under CC BY blood. 47  FEATURES OF THE FETAL CIRCULATION Structure Placenta attached to fetus by a cord (umbilical cord) Two umbilical arteries and one umbilical vein wrapped in a soft connective tissue coat. Functions Exchange substances, protection of the fetus and maintenance of pregnancy. 48  Placenta Functions Exchange of nutrients and wastes Deoxygenated fetal blood flowing through the network of placental capillaries absorbs oxygen and nutrients from maternal blood and excreted its wastes. Protection of the fetus Temporary passive immunity lasting for a few months is provided by maternal antibodies that cross the placenta before birth. Indirect exchange between the fetal and maternal circulation provides a ‘barrier’ to potentially harmful substances, including bacteria and drugs. Substance that cause abnormal fetal development-teratogen Important teratogen-alcohol, antibiotics, anticancer agents, ionising radiation and some infections (rubella virus, cytomegalovirus, syphilis) 49  Placenta Functions Maintenance of pregnancy Placenta has an essential function and secretes hormones that maintain pregnancy. From 12 weeks until delivery, placenta secretes increasing levels of oestrogen and progesterone, for maintaining pregnancy. 50  FETAL ADAPTATION Ductus venosus A continuation of the umbilical vein that returns blood directly into the fetal inferior vena cava, and most blood, therefore, bypasses the non- functional fetal liver. Ductus Arteriosus Small vessel connects the pulmonary artery to the descending thoracic aorta and diverts blood into the systemic circulation. 51  FETAL ADAPTATION Foramen ovale This is an opening in the septum separating the two atria. It is covered with a flap of tissue that acts as a one-way valve, allowing blood to flow between the right and left atria, so that most blood bypasses the non-functional fetal lungs. 52  CHANGES AT BIRTH When baby takes its first breath the lungs inflate for the first time, increasing pulmonary blood flow. Blood returning from lungs increases the pressure in the left atrium, closing the flap over the foramen ovale and preventing blood flow between the atria. Blood entering right atrium is therefore diverted into the right ventricle and into pulmonary circulation through pulmonary arteries. As pulmonary circulation is established, blood oxygen levels increase, causing constriction and closure of the ductus arteriosus. 53 54 Brain exercise Describe the structure and function of the placenta. What is the function of ductus venosus? 55  CONCLUSION Blood flows from the heart through elastic arteries, muscular arteries, and arterioles to the capillaries. Blood returns to the heart from the capillaries through venules, small veins, and large veins. Pulmonary circulation moves blood to and from the lungs. The pulmonary trunk arises from the right ventricle and divides to form the pulmonary arteries, which projects to the lungs. Arteries carry blood from left ventricle of the heart to all parts of the body. The three major veins returning blood to the heart are superior vena cava, the inferior vena cava and coronary sinus. Veins are of three types: Superficial, deep and sinuses. 56