Physiology No 3

‫بســـم الله الرحمن الرحيم‬

‫المحاضرة‬ ‫الثالثة‬

‫من صـــفحة ‪ 45‬الى صــفحة ‪49‬‬ ‫‪ +‬من صـــفحة ‪ 51‬الى صــفحة ‪58‬‬ ‫مع ملحظة أن المطلوب من صفحة‬ ‫‪ 51‬تعريف الـ‬ ‫‪open & Closed circulatory systems‬‬ ‫فقط‬

Depots Situated Mesenteries Mobilized Besides Repair of injured tissues Formation of skin, hair & nails Precursors Degradative pathways Deamination Transamination Nonessential amino acids Polymerization Excreted Urine Urea Destruction Blood coagulation Anticoagulant Detoxication

‫مخازن‬ ‫تقع‬ ‫المساريقا‬ ‫تحتشد أو تتحرك‬ ‫بجانب‬ ‫اصلح النسجة المصابة‬ ‫ الشعر & الظافر‬،‫تكوين الجلد‬ ‫بشير بمن سيأتى بعده‬ ‫المسارات التحليلية‬ ‫نزع مجموعة المين‬ ‫نقل مجموعة المين‬ ‫الحماض المينية غير الساسية‬ ‫التبلمر‬ ‫يفرز أو يخرج‬ ‫بول‬ ‫يوريا‬ ‫تكسير أو هدم‬ ‫تجلط الدم أو تخثره‬ ‫مضاد للتجلط‬ ‫نزع السمية‬

Fat metabolism * Absorbed fats are stored as neutral fat in the fat depots such as under the skin, in the mesenteries, at the back of the abdomen … etc. * Incorporated into the structure of cells. * A source of energy where the fat is mobilized from the fat depots and passes to the liver. Fat

Liver lipase

Glycerol

+

Fatty acids β-Oxidation

Triose phosphate

Acetyl-CoA

Added to that coming Join the citric acid from glucose cycle

β-Oxidation General structure of fatty acids: δ

γ

β

α

R - CH2 - CH2 ---------- CH2 - CH2 - CH2 - CH2 - COOH Oxidation takes place in the carbon atom of theβ.- position

Mechanism of β-Oxidation CH2

R (CoA + ATP)

CH2 Fatty acid

CH2

CH2 CH2 Active fatty acid

COOH

R

CH2

R

CH2 CH CH CO S-CoA + 2H α,β-unsaturated fatty acid- CoA

Dehydrogenation

Hydration

CO

CH2 CH2 CHOH CO β-hydroxy fatty acid-CoA

R

S-CoA

S-CoA

Dehydrogenation R Cleavage at the β-carbon atom + CoAHydration R

CH2

CH2 CO CO S-CoA β-keto fatty acid-CoA

CH2 CO Active fatty acid (with 2 C less) Repeated the previous processes

S-CoA

+

CH3

+ 2H

CO S-CoA Acetyl CoA Enters the citric acid cycle

Protein metabolism * Absorbed amino acids are incorporated into protein needed for growth, repair of injured tissue, the formation of enzymes,some hormones, skin, hair, nails …etc. * May converted into other amino acids e.g. phenylalanine → tyrosine. * Used as a precursors for purines, pyrimidines, creatine, thyroxine, neurotransmitters … etc. * Used as a source of energy. Degradative pathways of most amino acids begins by deamination. There are two major routes of deamination which are: 1- Transamination & 2- Oxidative deamination. 1- Transamination

COOH

COOH

CH2 CH2 CHNH2

+

C

O

COOH

COOH Glutamic acid (Amino acid)

CH3

CH2

CH3

Pyruvic acid (Keto acid)

CH2 C

+ O

COOH

α- Ketoglutaric acid (Keto acid)

CHNH2 COOH Αlanine (Amino acid)

Notes: 1- Transamination does not result in net deamination. 2- It provides the basis for the formation of nonessential amino acids.

2- Oxidative deamination. CH3

CH

COOH

+

NAD

Dehydrogenation

+

NH2 Amino acid (Alanine)

Coenzyme

CH3

COOH

C

+

NADH

+

NH3

NH Imino acid

+ H2O * Glucose * Glycogen Fatty acids

Polymerization

* Acetyl CoA

CH3

C

COOH

O Keto acid (Pyruvic acid)

* Join the citric acid cycle * Used for the synthesis of new amino acids + 4 ) in the urineExcreted as ammonium ions (NH * Converted into urea in the liver & excreted in the urine *

Functions of the liver .Secretion of bile which helps in the digestion & absorption of fats -1 .}!!!!!! Destruction of red blood cells (RBCs) }+ formation of RBCs -2 .Acts as an iron depot -3 .Acts as a blood depot -4 Has a role in the synthesis of important compounds such as plasma -5 proteins which are necessary for: * Blood coagulation e.g. fibrinogen & prothrombin. .* Anticoagulant e.g. heparin .Acts as a center of storage of glycogen, vitamins especially A, D & B -612 .Acts as a central organ of metabolism -7 Acts as a center of detoxication either by: -8 * Conjugation: where the toxic substance is combined with another molecule or chemical group producing a compound being non-toxic and excreted in the urine. * Oxidation or reduction: where the toxic substance is oxidized or reduced .to a less toxic substance

Contained within blood vessels Pump Bathes Sinuses Sluggish Grasshopper Earthworm Atrium )auricle( Ventricle Capillary bed )network( Gills Oxygenated blood Pulmonary circulation Systemic circulation Adequate Human Tricuspid valve Bicuspid valve )mitral valve( alveoli Coronary artery

‫يحتوى فى أوعية دموية‬ ‫يضخ‬ ‫يسبح أو تحمى‬ ‫جيوب‬ ‫بطىء‬ ‫الجندب أو الجراد الصغير‬ ‫دودة الرض‬ ‫الﺫين‬ ‫البطين‬ ‫شبكة من الشعيرات الدموية‬ ‫خياشيم‬ ‫دم مؤكسج‬ ‫الدورة الرئوية‬ ‫الدورة الجهازية أو العامة‬ ‫كافى‬ ‫انسان‬ ‫صمام ثلثى الشرافات‬ )‫صمام ﺫو شرافتين (الصمام الميترالى‬ ‫حويصلت هوائية‬ ‫الشريان التاجى‬

Blockage Anterior )superior( vena cava Posterior )inferior( Head, arms & chest Remainder 1st set Device Cessation Consciousness Weighs Intrinsic Spontaneously & rhythmically Pacemaker Node Embedded Systole Diastole Semilunar valves The pulse

‫انسداد‬ ‫الوريد الجوف المامى أو العلوى‬ ‫الخلفى أو السفلى‬ ‫ الزراعين & الصدر‬،‫الرأس‬ ‫الباقى‬ ‫السلسلة الولى‬ ‫جهاز‬ ‫توقف‬ ‫التنبه‬ ‫يزن‬ ‫جوهرى أو حقيقى‬ ‫تلقائى & ايقاعى‬ ‫منظم ضربات القلب‬ ‫عقدة‬ ‫مغمورة أو مطمورة‬ ‫انقباضى‬ ‫انبساطى‬ ‫صمامات هللية أو نصف قمرية‬ ‫النبضة‬

Circulatory system Open circulatory system: * The blood is not always contained within blood vessels. * The blood runs in a sluggish (slow) manner. * The heart pumps blood into vessels, then these vessels empty either into: & Body cavities where blood bathes the internal organs, & Sinuses located within the organs themselves. e.g. Grasshopper.

Closed circulatory system: * The blood is always contained within blood vessels. * The blood runs not in a sluggish (slow) manner due to the pumping of the heart. .e.g. Earthworm & vertebrates Artery: It is blood vessel which conveys the blood away from the heart. It is the strongest of the blood vessels. It is able to expand and constrict. Vein: It is the blood vessel that returns blood to the heart. Heart → artery → arterioles → capillary bed (network) → venules → vein → heart

Types of circulatory pathways in vertebrates

One-circuit pathway: e.g. Fishes. * The heart consists of one atrium (auricle) & one ventricle. * The ventricle pumps blood under pressure to the gills where it is oxygenated. * The oxygenated blood distributed to the tissues. * Then, it returns as deoxygenated form to the atrium → ventricle → gills → tissues ... etc. Double-circuit pathway: e.g. Other vertebrates such as human. Where there is: @ Pulmonary circulation: * The heart (right ventricle) pumps deoxygenated blood to the lungs to be oxygenated and returns back to the heart (left atrium). @ Systemic circulation: * The heart (left ventricle) pumps oxygenated blood to the tissues and returns back to the heart (left atrium) as deoxygenated blood. Double-circuit pathways assure adequate blood pressure and flow to the tissues.

In amphibians, the pulmonary circulation is not separated from the systemic circulation where oxygenated blood mixes with deoxygenated blood. This is due to the amphibian’s heart has a single ventricle. In other vertebrates, there is a separation from the two pathways due to the presence of two ventricles.

Human circulation

Human circulation 1- Has a closed circulatory system. 2- Has four-chambered heart (right & left atria and right & left ventricles). 3- Has both pulmonary and systemic circulatory pathways which are separated. Blood pathways: Pulmonary circulation: All Deoxygenated blood Capillaries in the lungs around alveoli where gas exchange takes place

enters

Arterioles

2 Pulmonary arteries

Oxygenated blood

Bicuspid valve (mitral valve)

Pulmonary venules

Left ventricle

Pulmonary veins Aorta

(the large arterial trunk)

Superior (anterior) vena cava Right atrium

Right ventricle Pulmonary trunk

Left atrium

:Systemic circulation Oxygenated blood in the left atrium

Tricuspid valve

Right atrium

(head, arms & chest)

+ Inferior (posterior) vena cava

All parts of the body

(the large arterial trunk the 1st is the coronary arteries that supply the heart

The blood becomes deoxygenated

(remainder of systemic circulation)

Note: Any blockage in coronary arteries leads to a heart attack ( ‫) نوبة قلبية‬.

Portal circulation It begins and ends in capillaries. e.g. hepatic portal circulation. The 1st set of capillaries occurs at the digestive organs (at the begining of the hepatic portal vein) while the 2nd set occurs in the liver (at the end of hepatic portal vein). Notes: * The difference between hepatic portal vein & hepatic vein (that enters the posterior vena cava). * The presence of renal portal circulation.

:The human heart It is a pumping device with continual without rest & regular beating (heartbeats) which is essential for life. If circulation to the brain stops for: * 5 seconds → consciousness is lost. * 4 minutes → death of a large number of brain cells. * 9- 10 minutes → irreversible & massive brain damage → death. The heart beats about 70 times/minute for a normal, adult resting person. The heart pumps about 5 liters / minute (≈ total blood volume). The heart weighs about 300 g (≈ less than 0.5% of total body weight).

Control of the heartbeats The contraction of the heart is intrinsic to the heart i.e. it does not require outside nervous stimulation. Proof: The dissected cardiac muscles from the heart can still beat spontaneously & rhythmically.

:The control of the heartbeats # It is regulated by the pacemaker where: 1) There is a small node of myocardial cells called the sinoatrial node (SA node). 2) It is embedded in the right atrial wall. 3) It initiates a wave of excitation every 0.85 sec. 4) This wave of excitation spreads quickly throughout the atria which leads to the contraction (systole) of the atria while the ventricles are still relax (resting) (diastole). 5) After the wave makes a contact with atrioventricular node (AV node) which located at the base of the right atrium, the ventricles contract (systole). 6) While the ventricles contract, the atria rest (relax) (diastole). 7) Following ventricular systole, the entire heart rests (diastole).

The heart cycle: Time

Atria

Ventricles

0.15 sec

Systole

Diastole

0.30 sec

Diastole

Systole

0.40 sec

Diastole

Diastole

# The heartbeats may be speeded up or slowed down by nervous stimulation where: A cardiovascular center in the medulla oblongata }portion of the brain} alters the heartbeat by autonomic nervous system (sympathetic & parasympathetic systems). The sympathetic system increases the heartbeats while parasympathetic system slow down the heartbeats. Various factors such as the relative need for oxygen or the level of blood pressure determine which of these systems is activated. The heartbeat sound: It is heared as (lubb-dup) which is caused by the closing of valves. There are 2 types of valves which are: 1) Atrioventricular (cuspid) valves: They conduct blood from the atria to the ventricles. 2) Semilunar valves: They conduct blood from the ventricles to their respective arteries (aorta & pulmonary arteries). These valves permit only one-way flow of blood and do not allow a backward flow. The pulse: It is a wave of vibration that passes down the walls of the arterial blood vessels when the aorta expands following ventricle systole. So, the arterial pulse can be used to determine the heart rate.

Blood pressure & systemic blood flow: When the left ventricle contracts, blood is forced into the arteries under pressure which is called systolic pressure. Diastolic pressure is the pressure in the arteries during ventricular diastole. Human blood pressure is normally measured on the brachial artery and is stated in mmHg. A blood pressure reading consists of two numbers, for example, 120/80, that represent systolic and diastolic pressures, respectively.

Notes: As blood flows through the aorta and then enters into smaller arteries and arterioles, pressure falls. The differences between systolic & diastolic pressures decreases gradually and then finally disappears in the capillaries. Blood pressure in the venules is very low (10 mmHg) and finally falls to 2 mmHg or less in the vena cava. So, the very low blood pressure in the veins is not sufficient to move the blood back to the heart, especially from the limbs of the body. To avoid this, there are two mechanisms which are: 1) The contraction of skeletal muscles near these veins. 2) Veins have valves that prevent backward flow of blood.

‫الى‬ ‫اللقــــــــــــــــــ‬ ‫ـاء‬ ‫أ‪ .‬د‪ .‬شــــــبل‬ ‫شـــــــــعلن‬