BIO 116-A&P Final

Female Reproductive System 21 Male Reproductive System 23 Pregnancy and Development 15 Endocrine 13 Cardio 25

The Heart has How Many Side-By-Side Pumps

Two

Right Side of Heart

Receives oxygen-poor blood from

How Oxygen-poor Blood Moves

Pumps to lungs from tissues to get rid of CO₂, pick up O₂

Pumps to lungs from tissues to get rid of CO₂, pick up O₂ Via?

Pulmonary circuit

Left Side of Heart

Receive oxygenated blood from lungs

How Oxygenated Blood Moves

Pumps from lungs to body tissue

Pumps Oxygenated Blood to Body tissues Via?

Systemic circuit

How the Blood Flows Throughout the Body

Oxygen-rich blood from the lungs enters the left side of the heart:

• Oxygen-rich blood from the lungs enters the left atrium through the pulmonary veins

• The left atrium then pumps the blood into the left ventricle

• The left ventricle is the heart’s main pumping chamber, responsible for sending blood to the rest of the body

Oxygen-rich blood is pumped to the body through arteries:

• The left ventricle pumps oxygen-rich blood through the aorta, the body’s main artery

• The aorta branches into smaller arteries, delivering blood to all parts of the body. 

• As the blood travels through the arteries, it branches into smaller and smaller vessels called arterioles. 

Oxygen is delivered to tissues and carbon dioxide is picked up in capillaries:

• Arterioles lead to capillaries, which are tiny blood vessels with thin walls that allow for the exchange of substances.

• At the capillaries, oxygen and nutrients are released from the blood into the body's tissues, and carbon dioxide and waste products are taken up.

Deoxygenated blood returns to the heart through veins:

• The blood, now deoxygenated and containing waste products, flows from the capillaries into venules (small veins).

• Venules connect to larger veins, which carry the blood back to the heart.

• The superior and inferior vena cava, two large veins, bring blood back to the right atrium of the heart.

The cycle repeats:

Receiving Chambers of the Heart

Right Atrium

Left Atrium

Right Atrium

Receives blood returning from systemic circuit

Left atrium

Receives blood returning from pulmonary circuit

Heart Location

Mediastinum

Mediastinum

Area between the lungs

Include the heart and its large veins and arteries, the trachea, the esophagus, the bronchi, and lymph nodes

Between second rib and fifth intercostal space

On superior surface of diaphragm

Anterior to vertebral column
Posterior to sternum

Heart Anatomy

Approximately size of fist

Base

Apex

Apical impulse

Base of Heart

Posterior surface

Leans toward right shoulder

Apex of Heart

Points toward left hip

Apical Impulse of Heart

Palpated between fifth and sixth ribs

Just below left nipple

Covering of the Heart

Pericardium

Pericardium

Double-walled sac

Superficial fibrous pericardium

Deep two-layered serous pericardium

Superficial fibrous pericardium

Protects, anchors to surrpunding structures, and prevents overfilling

Deep two-layered serous pericardium

Parietal layer

Visceral layer (epicardium)

Two layers separated by fluid-filled pericardial cavity (decreases friction)

Parietal layer

Lines internal surface of fibrous pericardium

Visceral layer (epicardium)

On external surface of heart

Homeostatic Imbalances

Pericarditis

Cardiac Tamponade

Angina Pectoris

Myocardial infarction

Incompetent or Insufficient or Leaky Valve

Valvular Stenosis

Arrhythmias

Fibrillation

Ectopic focus

Extrasystole

Heart block

Hypocalcemia

Hypercalcemia

Hyperkalemia

Hypokalemia

Tachycardia

Bradycardia

Pericarditis

Inflammation of pericardium

Roughens membrane surface → pericardial friction rub (creaking sound) heard with stethoscope

Cardiac Tamponade

Excess fluid sometimes compresses heart → limited pumping ability

Layers of the Heart Wall

Epicardium

Myocardium

Endocardium

Epicardium

Visceral layer of serous pericardium

Myocardium

1. Spiral bundles of contractile cardiac muscles cells

2. Cardiac “skeleton”

Cardiac “skeleton”

Crisscrossing

Interlacing layer of connective tissue

Anchors cardiac muscle fibers

Supports great vessels and valves

Limits spread of action potentials to specific paths

Endocardium

Continuous with endothelial lining of blood vessels

Lines heart chambers

Covers cardiac skeleton of valves

Chambers of the Heart

Two superior atria

Two inferior ventricles

Interatrial septum

Separated atria

Has the fossa ovalis

Fossa ovalis

Remnant of forament ovale of fetal heart

Interventricular septum

Separates ventricles

Coronary sulcus (atrioventricular groove)

Encircles junction of atria and ventricles

Anterior interventricular sulcus

Anterior position of interventricular septum

Posterior interventricular sulcus

Landmark on posteroinferior surface of the heart that indicates the boundary between the left and right ventricles.

Atria

Small, thin-walled

Contribute little to propulsion of blood

Three veins empty into right atrium

Four pulmonary veins empty into left atrium

Veins empty into Right Atrium

Superior vena cava

Inferior vena cava

Coronary sinus

Right atrium

Shows pectinate muscles

These muscles from ridges (comb looking lines)

Left Atrium

Shows pectinate muscles only in auricles

Auricles

Appendages that increase atrial volume

The Discharging Chambers

Right ventricles

Left ventricle

Trabeculae carneae

Papillary muscles

Trabeculae carneae

Irregular ridges of muscle on ventricle walls

Papillary muscles

Anchor chordae tendineae

Ventricles

Thicker walls than atria

Actual pumps of heart

Right ventricle

Left ventricle

Right ventricle

Pumps blood into pulmonary trunk

Left ventricle

Pumps blood into aorta

Aorta

Largest artery in body

Heart Valves

Ensure unidirectional blood flow through heart

Open and close in response to pressure changes

Two atrioventricular (AV) valves

Two semilunar (SL) valves

Two atrioventricular (AV) valves

Prevent backflow into atria when ventricles contract

Tricuspid valve

Mitral valve

Chordae tendineae anchor cusps to papillary muscles

Tricuspid valve

Right AV valve

Mitral valve

Left AV valve

Bicuspid valve

Chordae tendineae anchor cusps to papillary muscles

Hold valve flaps in closed position

Two semilunar (SL) vlaves

Prevent backflow into ventricles when ventricles relax

Open and close in response to pressure changes

Aortic semilunar valve

Pulmonary semilunar valve

Cardiac Muscle Cells

Have striations

Short

Branchedd

Interconnected

One or two nuclei

Have intercalated discs

Intercalated Discs

Junctions between cells

Ex. desmosomes and gap junctions

Allows heart to be functional syncytium

Desmosomes

Prevent cells from separating during contraction

Gap Junctions

Allow ions to pass from cell to cell

Electrical impulses can travel fast and at once

Coronary Circulation

The flow of blood that supplies oxygen and nutrients to the heart muscles

Arteries

Veins

Arteries

Arise from base of aorta

Carry blood away from heart

Almost always the blood is oxygenated except for pulmonary circulation and umbilical vessels of fetus

Left coronary artery branches to

Anterior interventricular artery

Circumflex artery

Left coronary artery Supplies

Interventricular septum

Anterior ventricular walls

Left atrium

Posterior wall of left ventricle

Right coronary artery Supplies

Right atrium

Most of right ventricle

Right coronary artery branches to

Right marginal artery

Posterior interventricular artery

Cardiac veins

Collect blood from capillary beds

Coronary sinus

Empties into right atrium

Formed by merging cardiac veins

• Great cardiac vein

• Middle cardiac vein

• Small cardiac vein

Great cardiac vein

Anterior interventricular sulcus

Small cardiac vein

Inferior margin

Middle cardiac vein

Posterior interventricular sulcus

Anterior Cardiac Veins

Empty directly into right atrium anteriorly

Angina Pectoris

Thoracic pain caused by deficiency in blood delivery to myocardium

Cells weakened

Myocardial infarction

Heart attack

Prolonged coronary blockage

Areas of cells death repaired with noncontractile scar tissue

This tissue won’t contract well

Capillaries

Contact tissue cells

Directly serve cellular needs

Veins

Carry blood toward heart

Formed when venules converge

Have thinner walls, larger lumens compared with corresponding arteries

Blood pressure lower than in arteries

Thin tunica media; thick tunica externa of collagen fibers and elastic networks

Capacitance vessels

Lumen

Central blood-containing space

Three wall layers in arteries and veins

Tunica intima

Tunica media

Tunica externa

Tunica intima

Endothelium (made by endothelial cells)

Subendothelial layer: basement membrane of connective tissue

Endothelium (made by endothelial cells)

Lines lumen of all vessels

Continuous with endocardium in the heart

Slick surface reduces friction

Tunica media or muscularis

Smooth muscle and sheets of elastin

Sympathetic vasomotor nerve fibers control vasoconstriction and vasodilation of vessels

• Influencing blood flow and blood pressure

Tunica externa (tunica adventitia)

Made of collagen fibers to protect and reinforce

Anchor to surrounding structures

Contains nerve fibers and lymphatic vessels

Vasa vasorum (VV) of larger vessels nourished external layer

Arterial System

A network of blood vessels that carries oxygen-rich blood from the heart to the rest of the body

Elastic Arteries

Muscular Arteries

Arterioles

Elastic Arteries

Large thick-walled arteries with elastin in all three tunics

Aorta and its major branches

Large lumen offers low-resistance

Inactive in vasoconstriction (reduction of the lumen of the vessels)

Act as pressures reservoirs → expand and recoil as blood ejected from heart

Muscular Arteries

Distal to elastic arteries

Deliver blood to body organs

Thick tunica media with more smooth muscle

Active in vasoconstriction

Arterioles

The smallest arteries

Lead to capillary beds

Control flow into capillary beds via vasodilation and vasoconstriction

Capillaries

Microscopic blood vessels

Walls to the thin tunica intima

• in the smallest on a cell fills the entre lumen

• Diameter allows on single RBC to pass at a time for the exchange of gases, nutrients, wastes, hormones, etc., between blood and interstitial fluid

Structural types of the Capillaries

Continuous Capillaries

Fenestrated capillaries

Sinusoid capillaries (sinusoids)

Continuous capillaries

Tight junctions connect endothelial cells (skin and brain)

Fenestrated capillaries

Some endothelial cells contain pores

Fenestrations

Small intestines

Endocrine glands

Kidneys

Sinusoid capillaries (sinusoids)

Fenestrated and with larger intercellular spaces

The liver

Bone marrow

Spleen

Adrenal medulla

Blood Flow Through Capillary Beds

Metarterioles

Have precapillary sphincters made of smooth muscles cells

Sphincters regulate blood flow into true capillaries

• blood may go into true capillaries or to shunt

Regulated by local chemical conditions and vasomotor nerves

Metarterioles

Small vessels linking arteries with capillaries

Venous System

The network of veins in the body that carries deoxygenated blood back tot he heart, and then to the lungs for oxygenation

Venules

Veins

Venules

Formed when capillaries unite

Smallest veins

Very porous

Allow fluids and WBCs into tissues

Consist of endothelium and a few pericytes

Larger ones have one or two layers of smooth muscle cells

Pericytes

Calls that help to stabilize blood vessel walls and they also control permeability

Capacitance Vessels

Blood reservoirs

Contain up to 65% of blood supply

Blood vessels, primary veins, that can accommodate a large volume of blood with minimal change in pressure

How the blood in the veins returns to heart despite low pressure?

Large-diameter lumens offer little resistance

Venous valves prevent backflow of blood

• Most abundant in veins of limbs

Venous sinuses: flattened veins with extremely thin walls (e.g., coronary sinus of the heart and dural sinuses of the brain)