Anat and Phys Exam 4

Visceral pericardium

-On surface
-Simple squamous epithelium

Parietal pericardium

-Pericardial sac around heart
-Simple squamous epithelium with some loose CT

Pericardial space

-Contains pericardial fluid
-Lubrication and protection

What are the three layers of the heart?

1. Epicardium
2. Myocardium
3. Endocardium

Epicardium

-Outermost layer
-Visceral pericardium

Myocardium

-Middle layer
-Cardiac muscle (straited)

Endocardium

-Inner lining that lines the chambers
-Simple squamous epithelium

Right and left atria

-Thin walled
-Irregular shape
-Located cranial and dorsal

Interatrial septum

Divides the atrium

Right and left ventricles

-Thick walled, angled
-Located caudal and ventral
-Left ventricle much thicker than right

Interventricular septum

Divides the ventricles

Atrioventricular (AV) valves

-Right: tricuspid
-Left: bicuspid/mitral
-Separates each atrium from ventricle

Chordae tendinae

Strings attached to the ventricular wall

Papillary muscles

Attach chordae tendinae to heart

Semilunar valves

-Aortic: Between left ventricle and aorta
-Pulmonary: Between right ventricle and pulmonary artery

Intercalated disks

-Specialized cell junctions for AP flow
-Contract as one unit

Purkinje fibers

Specialized cells for initiation and carrying of AP quickly

Sinoatrial node

-Pacemaker of the heart
-Located in the right atrium

Intrinsic

-No nerve impulse needed
-Initiates its own AP within the heart itself

Involuntary

-Not under conscious control
-ANS (parasympathetic/sympathetic) controls rate and force

What kind of circulatory system do mammals have?

Dual circulatory system (pulmonary and systemic)

Pulmonary circuit

-Right side of heart
-Heart to lungs and back
-pick up oxygen and give off CO2

Systemic circuit

-Left side of heart
-Heart to body and back
-Pick up CO2 and give off oxygen to tissues

Artery

-From the heart to the body
-Usually carry oxygenated blood

Veins

-From the body to the heart
-Usually carry deoxygenated blood

Pulmonary circuit pathway

Vena cava --> right atrium --> Tricuspid valve --> right ventricle --> pulmonary semilunar valve --> pulmonary artery --> smaller arteries --> smaller artioles --> capillaries --> alveoli --> lungs --> venules --> veins --> larger veins --> pulmonary vein --> left atrium

Systemic circuit pathway

left atrium --> mitral/bicuspid valve --> left ventricle --> aortic semilunar valve --> aorta --> large arteries --> smaller arteries --> arterioles --> capillaries --> venules --> veins --> larger veins --> cranial/caudal vena cavae

Electrical conduction in the heart

1. fluctuating resting membrane potential
2. depolarization
3. Plateau phase
4. repolarization

Fluctuating resting membrane potential

Leaky Na+ channels allows cells cell to reach threshold

Depolarization

Voltage gated Na+ channels open and Na+ rushes into the cell for rapid voltage increase

Plateau phase

Ca++ enters cell

Repolarization

K+ leaves cell

ECG (Electrocardiogram)

-Measures electrical movement across heart
-Describes heart rate and regularity of beats

Sinus rhythm

Normal rhythm in ECG

What are the 4 parts of the ECG

1. P wave
2. PR interval
3. QRS complex
4. T wave

P wave

Depolarization of atria

PR interval

Conduction through AV valve

QRS complex

Depolarization of ventricles (strongest and fastest)

T wave

Repolarization of ventricles

Cardiac cycle

-Physical and mechanical events of heart filling and contraction
-Systole and diastole

Systole

-Contraction
-Creates high pressure

Diastole

-Relaxation and filling
-Lower pressure

S1 (lub sound)

-First heart sound
-AV valves close
-Ventricular pressure greater than atrial

S2 (dub sound)

-Second heart sound
-SL valves close
-Atrial pressure greater than ventricular

Heart murmers

Valves don't close completely or blood flow is extra turbulent

Mammalian fetal circulation

-Fetus isn't breathing and liver isn't working
-Has 2 special vessels through the umbilical cord

Umbilical vein

-1 vessel from placenta to fetus
-Relatively oxygen and nutrient rich blood

Umbilical arteries

-2 vessels from fetus to placenta
-Relatively oxygen and nutrient poor blood

What are the 3 shunts in mammalian fetal circulation

1. Ductus venosus
2. Foramen ovale
3. Ductus arteriosus

Ductus venosus

-Bypasses liver
-Umbilical vein connects to caudal vena cava

Foramen ovale

-Right to left atrium
-Bypasses lungs
-Will close with the first breath

Ductus arteriosus

-Pulmonary artery to aorta
-Bypasses lungs

Mammalian fetal circulation pathway

Placenta capillaries --> venules --> umbilical vein --> ductus venosus --> caudal vena cava --> right atrium --> foramen ovale --> left atrium --> left AV valve --> left ventricle --> aortic SL valve --> aorta --> same as adult except blood goes out umbilical artery to placenta instead of back to heart

Portal systems

Blood system from one organ of body to another bypassing general circulation

What are the two portal systems?

1. Hepatic
2. Renal

Hepatic portal system

-liver processes nutrients
-"filters" blood (wastes and drugs)

Hepatic portal vein

Collects blood from GI tract to liver

Renal portal system

-hind limbs to renal portal system to kidneys
-filters toxins before sending back to general circulation
-Found in lower vertebrates

Single circuit systems (ex. fish)

-Gills pick up oxygen in place of lungs
-2 chambers in heart (atrium and ventricle)
-Blood passes through heart only once

Operculum

Slit that opens in fish and exposes gills to water

Amphibian circulatory system

-Start with gills and eventually develop lungs
-3 chambered heart (2 atria and 1 ventricle)
-Spiral groove in ventricle

Spiral groove

Mixing of oxygenated and deoxygenated blood

Reptile circulatory system

-Most have 3 chambered hearts (2 atria and 1 ventricle)
-More separated so less mixing of oxygenated and deoxygenated blood by trabeculae in ventricles

What are the 3 layers in arteries and veins?

1. Tunica externa or adventitia
2. Tunica media
3. Tunica intima

Tunica externa or adventitia

-Loose connective tissue
-Thickness varies with vessel size (artery is thicker, vein is thinner)

Tunica media

-Smooth muscle
-Doesn't pump blood
-Constricts or dialates muscle
-Elastic CT in arteries, loose CT in veins
-Thicker in arteries than veins

Arteries in tunica media

-Pressure reservoirs
-Allows for expansion

Veins in tunica media

-Smaller
-Volume reservoirs
-Expandable

Tunica intima

-Deepest simple squamous epithelium
-allow for diffusion

Exceptions to arteries carrying oxygenated, veins carrying deoxygenated

-Pulmonary artery
-pulmonary vein
-fetal arteries and veins

Capillaries

-network of blood vessels found all over the body
-Endothelium (tunica intima) only
-Entered by arterioles and exited by venules

Arterioles

Smaller arteries

Venules

Smaller veins

Precapillary sphincter

-smooth muscle around arteriole
-shunts blood to areas that need oxygen

Hydrostatic pressure

Generated by pressure of fluid inside and outside the capillary

Oncotic pressure

Pressure of proteins in interstitial space

Starling forces

-Balance between the hydrostatic pressure gradient and the oncotic pressure gradient across the capillary
-Forces out O2, AA's, hormones, water and recover fluid

Movement of blood through vessels

-Heartbeat creates pressure wave
-Maintained by elasticity of arterial walls
-Blood flows from high to low pressure

How does blood get back to the heart?

-In veins, no elasticity and drop in pressure
-Skeletal muscle contraction to move body
-Smooth muscle contraction in internal organs
-Valves prevent backflow
-Breathing creates vacuum

Lymphatic system

-Part of circulatory system
-Thin-walled lymphatic vessels
-Have the same 3 layers as veins
-Recovers fluid and proteins
-Lymph vessels parallel veins

Lymph

Flows through lymphatic system instead of blood

Lacteals

-Lymph vessels from intestine
-Contain chyle

Chyle

High-fat lymphatic fluid

Lymphatic nodules and nodes

-Collections of lymphocytes
-Helps with immunity

What are the 5 palpable lymph nodes?

1. submandibular
2. prescapular
3. axillary
4. inguinal
5. popliteal

Submandibular lymph node

Under the jaw

Prescapular lymph node

Front of shoulder (scapula)

Axillary lymph node

Armpits

Inguinal lymph nodes

Inner thigh

Popliteal lymph nodes

Hind leg behind stifle (easiest one to find)

Spleen

-Largest lymphatic organ
-Immunity from lymphatic nodules
-RBC storage
-Filters and removes dead or dying cells
-Part of mononuclear-phagocyte system (MPS)

Mononuclear-phagocyte system (MPS)

One-nucleus phagocytic cells (garbage trucks of body)

What percent of body weight does blood make up?

7-10

What is the function of blood?

Transport gases, nutrients, hormones, heat, etc throughout the body

What is the normal pH of blood?

7.35-7.45

What is the composition of blood

-plasma/serum
-Formed elements (cells)

Plasma/serum

-55-70% of blood volume
-Liquid portion of blood

Erythrocytes (RBC)

-Contain hemoglobin to carry oxygen
-Round, biconcave, non-nucleated in most mammals (nuclei present in birds, reptiles and amphibians)
-Most common blood cells

Hemoglobin (Hb)

-Carries Oxygen
-Tetramer
-Globin (protein)
-Heme with iron

Leukocytes

-White blood cells (WBC)
-Kills foreign substances in cells