What are the three classes of hormones?
What two types of hormones are made from the amino acid tyrosine?
What are the two groups of lipid-derived hormones?
What is the main role of the hypothalamus?
What is another term for the anterior lobe or the pituitary gland?
What are the seven hormones secreted by the anterior pituitary gland?
Which of the seven hormones produce T₃ and T₄?
Which of the seven hormones target female mammary glands and functions in milk production?
What is another term for the posterior lobe of the pituitary gland?
What are the two hormones released by the posterior pituitary gland and what are their functions?
What are the two types of thyrocytes found in the thyroid gland?
How does calcitonin affect calcium levels in the body?
How many parathyroid glands are there, and where are they located?
What hormone is produced by the parathyroid glands, and what does it do - specifically, how does it affect calcium levels?
What are the two main parts of the adrenal glands and what do they secrete?
What enzyme and two hormones are produced by the kidneys?
What is the role of erythropoietin in the body?
What is the function of calcitriol?
What are the four types of cells found in the pancreas?
Which one of the four cells produces glucagon? And which produces insulin?
What do interstitial cells in the testes produce?
What do follicular cells in the ovaries produce?
Which part of the CNS is the pineal gland part of?
What hormone is produced by pinealocytes, and what is it derived from?
What is the main role of melatonin in the body?

Chapter 20. The Cardiovascular System: Blood

What are the two main components of blood?
What percentage of blood volume is plasma, and what is the primary component?
What are the three formed elements of blood?
What is the typical pH of blood? (it should be a range, not an exact number)
What are the three major classes of plasma proteins?
Which of the three plasma proteins are the major contributors to osmotic pressure?
What are the two types of globulins and their functions?
Which plasma proteins are the largest and are essential for blood clotting?
What are the other names for red blood cells and white blood cells?
Where are red blood cells produced and what is their life expectancy?
What is responsible for RBC’s ability to transport oxygen and carbon dioxide?
What is the difference in color between oxygenated and deoxygenated hemoglobin?
What are the two groups of white blood cells?
What are the three types of granular leukocytes, and what suffix do their names end with?
Which two of the three granular leukocytes are important for immune response?
What type of objects do eosinophils attack - what are their coated with?
What two substances do basophils release when they migrate to injury sites?
What are the two types of agranular leukocytes, and what suffix do their names end with?
Which agranular leukocytes are the largest, and what are the two types?
Which agranular leukocytes are responsible for specific immunity and what are their three functional classes?
What is the primary function of platelets in the body?
How are platelets formed - what type of cells do they originate?
How long do platelets circulate in the blood before getting phagocytized?
Differentiate between thrombocytopenia and thrombocytosis.
What is the process of blood cell formation called?
What type of cells give rise to all blood cells?
Where do erythropoiesis and leukopoiesis primarily occur?

Chapter 21. The Cardiovascular System: The Heart

What two main circuits make up the cardiovascular system, and what is the function of each?
What are the three main types of blood vessels?
Of the three, which blood vessel transports blood away from the heart?
Which blood vessels return blood to the heart?
What is the pericardium, and what are its two parts?
What are the three layers of the heart wall? (from outermost to innermost)
True or false: The cardiac muscle is striated and has a single central nucleus.
What are the various functions of the cardiac skeleton?
What are the two septa in the heart, and what do each of them separate?
Differentiate between the superior and inferior vena cava - where does it receive venous blood from?
What part of the heart has the thickest wall, and why?
What is the role of the heart valves?
What are the two atrioventricular valves? And what are their other names?
What are the two semilunar valves?
Between the atrioventricular and the semilunar valves, which one lacks chordae tendinae?
What muscles do chordae tendinae arise from, and what are their functions?
What is the function of coronary circulation?
Where do the right and left coronary arteries branch from?
What are the three cardiac veins that empty into the great cardiac vein or coronary sinus?
What is the term that describes the ability to generate and conduct impulses?
What is the cardiac cycle, and what are its two main phases? Differentiate between those two main phases.

Chapter 22. The Cardiovascular System: Vessels and Circulation

What are the three layers (in order) of the walls of arteries, arterioles, veins, and venules?
In veins, which layer is the thickest? In arteries, which layer is the thickest?
What is the term that describes smooth muscles contracting / reducing luminal diameter?
Between veins and arteries, which blood vessels lack valves?
What are the three categories of arteries, and which is the smallest?
What are the three types of capillaries?
Out of the three capillaries, which can be found in all tissues except epithelia and cartilage, and have endothelial cells connected by tight junctions and desmosomes?
Which capillaries contain “windows” or pores in their walls?
Which capillaries have gaps between their endothelial cells and permit the free exchange of water and solutes?
Where are sinusoids found? (list the four)
What is the term that describes a network of capillaries that supply blood to specific organs or areas of the body?
What are the smallest veins called, and where do they collect blood?
What is the luminal diameter of medium-sized veins?
Is blood pressure in venules and medium-sized veins high or low? And why?
Between arteries and veins, which contains most of our blood volume? What percent?
What is the first artery of the systemic circuit, and where does it exit?
What are the three subdivisions of the aorta?
What artery supplies blood to the neck, pharynx, esophagus, larynx, lower jaw, and face?
What are the two subdivisions of the descending aorta?
What [specific] vertebral level does the thoracic aorta begin?
What are the two branches of the thoracic aorta, and where does it supply blood?
What vertebral level does the abdominal aorta begin; what two arteries does it split into?
List the three unpaired arteries and the five paired arteries to which the abdominal aorta gives rise.
Where, in the heart, do systemic veins empty into?
Where does the superior vena cava receive blood from? And the inferior vena cava?
Which vein do the temporal and maxillary veins drain into?
Which vein does the facial vein drain into?
Where does the hepatic portal system begin and end?
Which digestive organ is the only organ that drains directly to the inferior vena cava?
What three large veins make up the hepatic portal system?

Chapter 23. The Lymphatic System

What two systems is the lymphatic system functionally part of?
What are the three main components of the lymphatic system?
What are the primary functions of the lymphatic system?
How does the lymphatic system help maintain blood volume?
What are the smallest lymphatic vessels?
How are lymphatic capillaries anatomically different from blood capillaries?
What are the three differences that distinguish larger lymphatic vessels and veins?
What role do valves play in small to medium-sized lymphatic vessels?
What are the two major lymph-collecting ducts?
Which of the two ducts collects lymph from the left side of the thoracic cavity and both sides of the body inferior to the diaphragm?
Which of the two ducts drains to the right subclavian and the right internal jugular vein?
What are the primary cells of the lymphatic system, and what are they responsible for?
What are the four types of T cells?
Which T cell is involved in direct cellular attack and provides cell-mediated immunity?
Which T cell responds to antigens that have already been encountered by cloning more lymphocytes?
When activated B cells divide, what two types of cells do their daughter cells differentiate into?
What are the functions of NK (natural killer) cells?
What is the life span of lymphocytes?
What are the three tonsils in the lymphatic system, and where are they located?
What is another term for the pharyngeal tonsil?
Between the thymus and the spleen, which is the largest lymphatic organ?
What does the thymus contain? (there are three)
What does the spleen remove? What does it store? And what does it contain?
What is the main function of the spleen?

Study Guide: Notes

Chapter 19. The Endocrine System

Three classes of hormones → all influence cellular operations by changing the types, activities, or quantities of key cytoplasmic enzymes

(1) Amino acid derivatives

Tyrosine derivatives

Thyroid hormones - released by thyroid gland
Catecholamines - epinephrine, norepinephrine, dopamine

Tryptophan derivative

Melatonin - synthesized by pineal gland

(2) Peptide hormones - released by pituitary gland
(3) Lipid derivatives - divided into eicosanoids and steroids

Hypothalamus

Coordinates activity of pituitary gland
Anterior lobe (adenohypophysis)

Three regions: pars distalis, pars tuberalis, pars intermedia
Secretes seven hormones → regulate other endocrine glands (see Fig 19.3)

Thyroid-stimulating hormone (TSH)

Targets thyroid gland; produces T₃ and T₄

Adrenocorticotropic hormone (ACTH)

Targets adrenal cortex; stimulates glucocorticoid secretion

Follicle-stimulating hormone (FSH)

In females → ovaries; follicle development and estrogen secretion
In males → nurse cells; sperm maturation

Luteinizing hormone (LH)

In females → targets ovaries; ovulation, corpus luteum formation, and progesterone secretion
In males → targets interstitial cells in testes

Prolactin (PRL)

Targets female mammary glands; milk production

Growth hormone (GH) or somatotropin

Targets all cells; growth, protein synthesis, lipid mobilization, catabolism

Melanocyte-stimulating hormone (MSH)

Targets melanocytes; melanin production in epidermis

Posterior lobe (neurohypophysis)

Extension of the CNS; stores and releases two hormones produced by the hypothalamus

Antidiuretic hormone (ADH) or vasopressin

Targets kidneys; promotes reabsorption of water and elevation of blood volume and blood pressure

Oxytocin

In females → targets uterus and mammary glands; causes labor contractions and milk ejection
In males → targets ductus deferens and prostate

Hypothalamus and Endocrine Regulation

Hypothalamic neurons produce ADH and oxytocin; after transport along their axons, these hormones are released from the posterior lobe
Integrative centers release regulatory hormones

Regulatory hormones control the activity of the anterior lobe
Reach their targets by the hypophyseal portal system

Autonomic centers control hormone secretion from the adrenal gland by sympathetic preganglionic motor neurons

Thyroid gland

Shaped like a butterfly; has two main lobes and an extensive blood supply

T thyrocytes → thyroxine (T₄) and triiodothyronine (T₃)

Increase energy utilization; increase oxygen consumption, growth, and development

C thyrocytes → calcitonin (CT)

Targets bones and kidneys; decreases calcium ion concentrations in body fluids

Parathyroid Glands

4 parathyroid glands located on the posterior surface; 2 inferior, 2 superior

Parathyroid hormone (PTH)

Targets bones and kidneys; increases calcium ion concentrations in body fluids (opposite of CT); increases bone mass

Thymus

Located within superior mediastinum of thoracic cavity → produces hormones important for immune defenses

Thymosins

Targets lymphocytes; maturation and functional competence of immune system

Adrenal Glands

Adrenal cortex

Secrete steroid hormones; subdivided into three zones

Zona glomerulosa (outer) produces mineralocorticoids
Zona fasciculata (middle) produces glucocorticoids
Zona reticularis (inner) secretes androgens

Adrenal medulla

Secrete catecholamines (released by chromaffin cells of adrenal medulla)

Epinephrine (adrenaline) and norepinephrine (noradrenaline)

Secretes 3x more epinephrine than norepinephrine
Speeds up use of cellular energy and mobilization of energy reserves
Increases muscular strength and endurance

Endocrine functions of the kidneys and heart

Some cells within the kidneys and heart function as endocrine glands

Their secretions regulate blood pressure and blood volume

Kidneys produce the enzyme renin and two hormones: peptide erythropoietin and steroid calcitriol

Erythropoietin - released in response to low oxygen levels in kidney; stimulates red blood cell production → increases blood volume and improves oxygen delivery to tissues
Calcitriol - secreted in response to presence of parathyroid hormone levels in the bloodstream

Pancreas → mixed gland with both exocrine (serous glands) and endocrine activities (pancreatic islets)

Alpha cells → produce glucagon

Increases blood glucose level by increasing rates of glycogen breakdown and glucose release by the liver

Beta cells → produce insulin

Lowers blood glucose level; increases rate of glucose uptake/utilization

Delta cells → produce somatostatin

Inhibits production and secretion of glucagon and insulin and slows the rates of food absorption and enzyme secretion by the digestive tract

F cells → produce pancreatic polypeptide (PP)

Inhibits gallbladder contractions and regulates the production of some pancreatic enzymes
May control rate of nutrient absorption by the digestive tract

Testes → interstitial cells produce androgens, especially testosterone

Nurse cells release inhibin

Ovaries → follicular cells produce estrogen (especially estradiol) and inhibin
Pineal gland → part of the epithalamus of CNS; contains two endocrine cells

Pinealocytes = secrete melatonin (derived from serotonin)

Melatonin slows the maturation of sperm, oocytes, reproductive organs

→ how? By inhibiting production of a hypothalamic-releasing factor that stimulates FSH and LH secretion

Collaterals from visual pathways enter the pineal gland and affect the rate of melatonin production

Melatonin production increases at night, decreases during the day
Important in regulating our circadian rhythms
Also an anti-oxidant that help protect CNS tissues from free radicals generated by active neurons and neuroglia

Interstitial cells = resemble neuroglia

Chapter 20. The Cardiovascular System: Blood

Blood = fluid connective tissue that consists of two components:

(1) Plasma

Liquid component; has a density slightly greater than water
Contains dissolved proteins and other solutes (nutrients, electrolytes, and wastes)
Approximately 55% of blood volume is plasma; water accounts for 92% of plasma volume

(2) Formed elements

Red blood cells, white blood cells, and platelets

RBCs transport oxygen and carbon dioxide
WBCs - components of immune system; less numerous than RBCs
Platelets - small, membrane-enclosed packets of cytoplasm containing enzymes and clotting factors

Blood = slightly alkaline; pH between 7.35 and 7.45; temperature of 38°C (100.4°F)

Hypovolemic (low), normovolemic, and hypervolemic (high) → refers to blood volumes

Differences between plasma and interstitial fluid

Similar ion concentrations but different concentrations of dissolved gases/proteins
Plasma proteins include albumins, globulins, and fibrinogen

Plasma proteins make up about 7% of plasma; there are three major classes

Albumins → 60% of plasma proteins; major contributors to osmotic pressure

Important in transporting fatty acids, thyroid hormones, steroid hormones

Globulins → 35% of plasma proteins

Immunoglobulins (antibodies) - aid in the body’s defense
Transport globulins - bind small ions, hormones, or compounds that either are insoluble or will be filtered out of the blood by the kidneys

Fibrinogen → 4% of plasma proteins; largest and essential for blood clotting

To prevent clotting, proteins are removed, leaving a fluid known as serum

Formed elements (3)

Red blood cells (erythrocytes)

Anucleate, biconcave discs, produced in red bone marrow
Function: transports oxygen from lungs to tissues, and carbon dioxide from tissues to lungs
120-day life expectancy (travels about 700 miles)
Mature RBCs consist of 66% water and 33% proteins

Hemoglobin (Hb) make up about 95% of RBC’s proteins; responsible for cell’s ability to transport oxygen and carbon dioxide
Oxygenated hemoglobin has a bright red color; deoxygenated is dark red
Each hemoglobin consists of a single molecule of heme, a nonprotein pigment that forms a ring surrounding iron ion

White blood cells (leukocytes)

Two groups: granular (has cytoplasmic granules) and agranular
Granular leukocytes (Tip: ends with -phils)

Neutrophils

Phagocytic cells important in immune response

Specialize in attacking/digesting bacteria

Highly mobile; first WBCs to arrive at an injury site
Short life span (10 hours) → dies after engulfing one to two dozen bacteria

Eosinophils

Phagocytic cells important in immune response

Attack objects coated with antibodies

Increases during an allergic reaction or parasitic infection
Release enzymes that reduce inflammation produced by mast cells and neutrophils; controls spread of inflammation

Basophils

Stain deep purple or blue; rare (<1% of WBC population)
Migrate to injury sites and release histamine and heparin

Histamine dilates blood vessels
Heparin prevents blood clotting

Agranular leukocytes (Tip: ends with -cytes)

Monocytes

Largest and account for 2-8% of WBCs
Free (highly mobile) vs. fixed macrophages (immobile)

Lymphocytes

Responsible for specific immunity (ability to attack invading pathogens/foreign proteins on an individual basis)
Three functional classes

T cells (T lymphocytes) → enter peripheral tissues and attack foreign cells directly
B cells (B lymphocytes) → differentiate into plasma cells (plasmocytes) that secrete antibodies that attack foreign cells or proteins
Natural kill (NK) cells → immune surveillance and destruction of abnormal cells; important in preventing cancer

Platelets

Small, membrane-bound, anucleate cytoplasmic fragments
Functions in blood clotting → formed from megakaryocytes
Continually replaced; circulates for 10-12 days before phagocytized

Microliter of circulating blood contains approx. 350,000 platelets

Thrombocytopenia = abnormally low platelet count (80,000 or less)
Thrombocytosis = abnormally high (more than 1,000,000)

In response to infection, inflammation, or cancer

Hemostasis = prevents loss of blood through walls of damaged vessels

Hemopoiesis

Process of blood cell formation; hematopoietic stem cells give rise to all blood cells

Erythropoiesis → formation of RBCs

In adults, it occurs primarily in red bone marrow; regulated by erythropoietin

Leukopoiesis → formation of WBCs

In adults, leukopoiesis occurs in red bone marrow

Chapter 21. The Cardiovascular System: The Heart

Cardiovascular system → heart and network of blood vessels
Blood vessel network is divided into two circuits (which beings and ends at the heart)

Pulmonary circuit = carries carbon dioxide-rich blood from the heart to the lungs, and returns oxygen-rich blood to the heart
Systemic circuit = transports oxygen-rich blood from the heart to the rest of the body’s cells, and returns carbon dioxide-rich blood back to the heart

Blood vessels

Arteries → transport blood away from the heart (Tip: Arteries = Away)
Veins → return blood to the heart
Capillaries → small, thin-walled exchange vessels connecting arteries and veins

Pericardium → surrounds the heart

Composed of two parts: outer fibrous and inner serous pericardium
Heart sits within mediastinum, located between two pleural cavities
Sits slightly to the left of the midline of mediastinum

Rotated to the left; causing right atrium/ventricle to be located more anteriorly within thoracic cavity than left atrium/ventricle

Structure of the heart wall (3 layers)

Epicardium (visceral layer of serous pericardium) → covers surface of heart

Two layers: mesothelium and a supporting layer of areolar tissue
Parietal layer of serous pericardium consists of an outer dense fibrous layer and an inner mesothelium

Myocardium → cardiac muscle tissue that forms the atria and ventricles

Atrial myocardium is thin; ventricular myocardium is thicker

Endocardium → covers inner surfaces, including heart valves; simple squamous

Cardiac muscle is striated

Have a single central nucleus, numerous mitochondria, large amounts of glycogen; intercalated discs form junctions between adjacent cardiac muscle cells
Features of intercalated discs

Plasma membranes of two cardiac muscle cells are bound by desmosomes; preventing separation during contractions
Possess a specialized junction (fascia adherens)
Cardiac muscle cells are connected by gap (communicating) junctions

Cardiac skeleton

Connective tissue; supports and reinforces heart, distributes heart muscle contractions, isolates atrial and ventricular muscle cells, and gives heart elasticity

Internal anatomy and organization of the heart

Interatrial septum = separates the right and left atria

The two atria receive blood

Interventricular septum = separates the right and left ventricles

The two ventricles pump blood away from the heart

Four sets of valves prevent backflow of blood, ensuring that blood flows from atria to ventricles, and from ventricles into the greater arteries exiting the heart
Superior vena cava (SVC) receives venous blood from head, neck, upper limbs, and chest
Inferior vena cava (IVC) receives venous blood from tissues and organs of the abdominal and pelvic cavities and lower limbs

Atriums and Ventricles (please refer to a diagram)

Right atrium

Receives oxygen-poor (deoxygenated) venous blood from the systemic and coronary circuits by the superior vena cava, inferior vena cava, and coronary sinus

Right ventricle

Oxygen-poor blood flows from right atrium through right AV valve into right ventricle → blood flows from right ventricle into pulmonary trunk to enter the pulmonary circuit
Blood passes through right AV valve (tricuspid valve)

Left atrium

Left and right pulmonary veins carry oxygen-rich blood from lungs to the left atrium
As blood flows from left atrium into left ventricle, it passes through left AV valve (mitral or bicuspid valve)

Left ventricle

Has the thickest wall of any heart chamber; extra-thick myocardium to enable enough pressure to force blood around systemic circuit
Blood leaving left ventricle passes through aortic valve into ascending aorta

Structure and function of heart valves

Valves are folds of endocardium extending into the openings between atria and ventricles → open and close to prevent backflow (a one-way flow; regurgitation)

Atrioventricular values (AV) = located between atria and ventricles

Chordae tendinae → arise from papillary muscles; limit movement of the cusps when valve closes, preventing backflow

Semilunar valves lack chordae tendinae

Pulmonary valve = between right ventricle and pulmonary artery
Aortic valve = between left ventricle and ascending aorta

Coronary blood vessels

Coronary circulation supplies blood to the muscle tissue of the heart; right and left coronary arteries are the first vessels to branch from the ascending aorta
Right coronary artery

Circles the heart to the right (viewed from above) within coronary sulcus
Gives off two major branches → right marginal branch and right posterior interventricular branch

Left coronary artery

Has a large diameter and supplies more blood than the right
Gives off four major branches: anterior interventricular, circumflex, left marginal, and posterior interventricular branches

Coronary veins

Collect blood from the heart wall and deliver it to the coronary sinus

Heart is drained by coronary sinus and anterior cardiac veins; which empty into the right atrium

Great cardiac vein and middle cardiac vein collect blood from small veins draining the myocardial capillaries; deliver venous blood to coronary sinus
Cardiac veins that empty into the great cardiac vein or coronary sinus:

(1) posterior vein of the left ventricle → draining the area served by the circumflex branch of the left coronary artery
(2) middle cardiac vein → draining the area supplied by the posterior interventricular branch of the left coronary artery
(3) small cardiac vein → receives blood from the posterior surfaces of the right atrium and right ventricle

Cardiac contractions

Automaticity or autorhythmicity = ability to generate and conduct impulses
Each contraction cycle follows a precise sequence: atria first then the ventricles
Nodal cells and conducting fibers coordinate the contractions

Cardiac cycle (complete heartbeat)

Period between the start of one heartbeat and the beginning of the next
Includes alternate periods of contraction and relaxation
For any one chamber in the heart, the cycle can be divided into two phases

During contraction (systole) a chamber ejects blood either to another heart chamber or into an arterial trunk
Systole is followed by the second phase: relaxation (diastole)

Chapter 22. The Cardiovascular System: Vessels and Circulation

Histological organization of blood vessels

Walls of arteries, arterioles, veins, and venules contain three layers:
Outer adventitia (tunica externa)

Forms a connective tissue sheath around the vessel
Thick layer; composed of collagen fibers, w/ scatter bands of elastic fibers
In veins, this layer is thicker than the media

Media (tunica media)

Smooth muscle cells encircle lumen of blood vessels
Vasoconstriction → smooth muscles contract, reducing luminal diameter
Vasodilation → relaxation of smooth muscles increases diameter of lumen
Any change in vessel diameter affects both blood pressure and blood flow
Arteries have a thin band of elastic fibers (external elastic membrane) located between media and adventitia

Intima (tunica intima)

Innermost layer of a blood vessel
In arteries, outer margin of intima contains thick layer of elastic fibers called internal elastic membrane
In the largest arteries, intima is thicker than in smaller arteries

Distinguishing arteries from veins

Walls of arteries are thicker than veins → media of an artery has more smooth muscle and elastic fibers
Vessel lumen → walls of an artery will contract, constricting the lumen

Arteries - retain their circular shape
Veins - look flattened or distorted

Vessel lining → arterial endothelial linings look pleated
Valves → veins contain valves to prevent backflow of blood toward capillaries

Arteries

Elastic arteries → large vessels with luminal diameters of up to 2.5 cm
Muscular arteries → transport blood to body’s skeletal muscles / internal organs
Arterioles → smaller than arteries

Capillaries

Wall of capillary is composed of one to three circularly arranged endothelial cells and underlying basal lamina

These thin walls allow exchange of nutrients and waste products

Continuous capillaries

Found in all tissues except epithelia and cartilage
Endothelium forms a complete lining, and endothelial cells are connected by tight junctions and desmosomes

Fenestrated capillaries

Contain “windows” or pores in their walls, due to an incomplete or perforated endothelial lining

Sinusoids (discontinuous capillaries)

Resemble fenestrated capillaries that are flattened and irregularly shaped
Commonly have gaps between endothelial cells, and the basil lamina is either thinner or absent
Permit the free exchange of water and solutes, such as plasma proteins, between blood and interstitial fluid
Blood moves through sinusoids slowly, maximizing the time available for absorption and secretion across the sinusoidal walls
Found in the liver, bone marrow, spleen, and adrenal glands

Four mechanisms responsible for exchange of materials across walls of capillaries and sinusoids

Diffusion across capillary endothelial cells (lipid-soluble materials, gases, and water by osmosis)
Diffusion through gaps between endothelial cells (water and small solutes; larger solutes in the case of sinusoids)
Diffusion through pores in fenestrated capillaries and sinusoids (water and solutes)
Vesicular transport by endothelial cells (endocytosis at luminal side, exocytosis at basal side)

Capillary beds

A network of capillaries supplying blood to a specific organ or area of the body
Blood flow through a capillary bed can vary

Veins

Venules

Smallest veins - collect blood from capillaries
Postcapillary venules - smallest venules that resemble expanded capillaries

Medium-sized veins

Luminal diameter ranges from 2-10 mm
Ex: most deep veins (radial, tibial, popliteal veins)

Venous valves

Blood pressure in venules and medium-sized veins are low → it can not overcome the force of gravity
In the limbs, medium-sized veins contain one-way valves that form from infoldings of the intima

Large veins

Include superior and inferior venae cavae + subclavian, renal, mesenteric, and portal veins within the abdominopelvic and thoracic cavities
Intima and media are small and difficult to distinguish in large veins

Distribution of blood and blood vessel

Veins normally contain most of our blood volume → 65 to 70%

Pulmonary circuit

Transports blood between heart and lungs

Specifically, it carries deoxygenated blood from heart → lungs, and returns oxygenated blood from lungs → heart

How? Pulmonary arterioles provide blood to capillary networks in alveoli (in lungs) which are thin enough to allow gas exchange between the capillary blood and inspired air

Systemic arteries

Transports blood between heart and all other tissues

In the periphery, oxygen diffuses from capillaries → interstitial space, and carbon dioxide diffuses from interstitial space → capillaries

Aorta

The first artery of the systemic circuit, exits from left ventricle

Subdivided into ascending aorta, aortic arch, descending aorta

Carotid arteries and blood supply to the brain

Ascend deep in the tissues of the neck, lateral to trachea
External carotid artery

Supplies blood to neck, pharynx, esophagus, larynx, lower jaw, and face

Internal carotid artery

Carotid sinus located at base of internal

Contains baroreceptors and chemoreceptors

Enter skull through carotid canals of temporal bones, delivering blood to brain

Three branches of internal carotid artery

Ophthalmic artery - supply eye
Anterior cerebral artery - supply frontal and parietal lobes
Middle cerebral artery - supply midbrain and lateral surfaces of cerebral hemispheres

Descending aorta

Thoracic aorta

Begins at level of vertebrae T1 and lies slightly to the left; gradually exits posterior mediastinum, and pass through diaphragm at the level of T12
Supplies blood to organs of thorax (except heart), muscles of the chest and diaphragm, and thoracic portion of spinal cord
Branches are grouped as either visceral or parietal

Visceral branches → supply organs of the chest

Bronchial arteries - passageways of lungs
Pericardial arteries - pericardium
Mediatinal arteries
Esophageal arteries

Parietal branches → supply chest wall

Intercostal arteries - chest muscles, vertebrae
Superior phrenic arteries - deliver blood to superior surface of muscular diaphragm

Abdominal aorta

Often surrounded by adipose tissue
Level of vertebra L4, it splits into right and left common iliac arteries → supply to deep pelvic and lower limbs

Region where aorta splits = terminal segment

Give rise to three unpaired arteries

(1) Celiac trunk → to liver, stomach, esophagus, gallbladder, duodenum, pancreas, spleen

Left gastric artery - stomach, esophagus (inferior)
Splenic artery - spleen, stomach, pancreas
Common hepatic artery - liver (mainly)

(2) Superior mesenteric artery → pancreas, duodenum, small intestine, most of large intestine
(3) Inferior mesenteric artery → colon, rectum

Give rise to five paired arteries

Inferior phrenic arteries - diaphragm, esophagus
Adrenal arteries - adrenal gland
Renal arteries - kidneys
Gonadal arteries - testes (males) and ovaries (females)
Lumbar arteries

Systemic veins

Drain all areas supplied by arterial branches → unite to form SVC and IVC; both empty into right atrium
Superior vena cava (SVC)

Receives blood from head, neck, chest, shoulders, upper limbs
Superficial veins of the head and neck

Temporal and maxillary veins → drain into external jugular vein
Facial vein → drain into internal jugular vein

Inferior vena cava (IVC)

Ascends to the right of aorta; collects most venous blood from organs inferior to diaphragm
Veins draining the abdomen

Lumbar veins - lumbar portion of abdomen
Gonadal veins (ovarian or testicular)
Hepatic veins - leave liver and empty at the level of vertebra T10
Renal veins - from kidneys; largest vessels draining into IVC
Adrenal veins
Phrenic veins - drain from diaphragm

Hepatic portal system

Begins in capillaries of digestive organs and ends in liver sinusoids

Liver is the ONLY digestive organ draining directly to IVC
Blood leaving the capillary beds supplied by the celiac, superior mesenteric, and inferior mesenteric arteries flows into the veins of the hepatic portal system instead of IVC

Hepatic portal vein = largest vessel in this portal system

Delivers venous blood to the liver
Receives blood from three large veins draining organs within the peritoneal cavity

Inferior mesenteric vein - large intestine (inferior)
Splenic vein
Superior mesenteric vein

Contributes the greater blood volume

Hepatic portal vein forms through the fusion of superior mesenteric and splenic veins

As it leaves to the liver, it receives blood from gastric (stomach) and cystic (gallbladder) veins

Chapter 23. The Lymphatic System

Lymphatic (lymphoid) system is functionally part of the circulatory and immune systems

Composed of lymphatic tissue, lymphatic organs, and lymphatic vessels

Lymphatic vessels transport lymph

Functions

Produces, maintains, and distributes lymphocytes
Maintains normal blood volume and eliminates local variations in the chemical composition of the interstitial fluid
Provides an alternate route for transporting hormones, nutrients, and wastes

Lymphatic vessels (lymphatics)

Carry lymph only from peripheral tissues to the venous system

Lymphatic capillaries

The smallest lymphatic vessels → as lymph moves from peripheral tissues toward the heart, the diameter of lymphatic vessels increases
Anatomically different than blood capillaries

Lymphatic capillaries are more permeable, have larger luminal diameters, have thinner walls, have a flat/irregular outline, and have collagenous anchoring filaments

Larger lymphatic vessels

Differ from veins in that (1) their walls are thinner, (2) have wider lumens, (3) there are no clear boundaries between their three layers
Small to medium-sized lymphatic vessels, like veins, have internal valves

Pressure within the lymphatic system is very low
Valves are essential to maintaining normal lymph flow toward thoracic cavity
Skeletal muscle contractions help move lymph through lymphatic vessels

Major lymph-collecting vessels

Thoracic duct

Collect lymph from the abdomen, pelvis, lower limbs, left side of the head, neck, and thoracic cavity

Aka from both sides of the body inferior to the diaphragm and from the left side of the body superior to the diaphragm

Drains into the left subclavian vein

Right lymphatic duct

Collects lymph from the right side of the thoracic cavity
Drains into venous system near the junction of the right internal jugular and right subclavian veins

Lymphocytes, primary cells of lymphatic system, are responsible for specific immunity

T cells (thymus-dependent)

Cytotoxic T cells = involved in direct cellular attack and provide cell-mediated immunity
Helper T cells = stimulate responses of both T and B cells; must activate B cells before it can produce antibodies
Regulatory T cells = subset of T cells that moderate immune response
Memory T cells = respond to antigens that have already been encountered by cloning (producing identical cellular copies) more lymphocytes to ward off the invader

B cells (bone marrow-derived)

Originate and become immunocompetent within red bone marrow
Account for 10-15% of circulating lymphocytes
Activated B cells divide, producing daughter cells that differentiate into plasma cells (plasmocytes) and memory B cells

Plasma cells → responsible for producing and secreting antibodies

NK cells (natural killer)

Remaining 5-10% are NK cells
Function: attack foreign cells, normal cells infected with viruses, and cancer cells that appear in normal tissues
Immune surveillance = constant monitoring of peripheral tissues by NK cells and cytotoxic T cells

Immune response destroys or inactivates pathogens, abnormal cells, and foreign molecules such as toxins

How? Direct attack by activated T cells and antibodies released by plasma cells derived from activated B cells

Distribution and life span of lymphocytes

Lymphocytes typically live longer than any other cellular formed element
Roughly 80% survive for 4 years, and some last 20 years or more
Lymphocytopoiesis maintains normal lymphocyte populations

Lymphatic tissues

Lymphatic tissues = connective tissues dominated by lymphocytes
Lymphatic nodules = aggregations of lymphocytes contained within a supporting framework of reticular cells and fibers
Mucosa-associated lymphoid tissue (MALT) = collection of tissues within the epithelia of the digestive, respiratory, urinary, and reproductive systems
Large nodules in the wall of the pharynx are called tonsils

Single pharyngeal tonsil (adenoid) - in posterior superior wall of the nasopharynx
Pair of palatine tonsils - in posterior, inferior margin of the oral cavity along the boundary of the pharynx to the soft palate
Pair of lingual tonsils - not visible; located deep to the mucosa at the base of the tongue

Lymphatic organs

Lymph nodes

Small and oval; surrounded by fibrous connective tissue capsule

1-25 mm in diameter; widely distributed throughout the body
Fibrous extensions from the capsule called trabeculae extend into the interior of the node

Distribution of lymphatic tissues and lymph nodes

Cervical lymph nodes = filter lymph originating in the head and neck, including lymphatic vessels within the meninges of the brain
Axillary lymph nodes = at the trunk from upper limbs; in women, axillary nodes drain lymph from mammary glands
Popliteal lymph nodes = at the thigh from leg; and inguinal lymph nodes from lower limbs
Thoracic lymph nodes = from the lungs, respiratory passageways, and mediastinal structures
Abdominal lymph nodes = filter lymph arriving from urinary and reproductive systems
Intestinal and mesenteric lymph nodes = filter lymph originating from digestive tract

Thymus

Contains developing T cells, reticular cells, and thymic corpuscles
Reaches its greatest size in the first year or two after birth

Reaches its maximum size during puberty, weighing 30-40 g
After puberty, it gradually shrinks and functional cells are replaced by fibrous connective tissue fibers and fat = involution of thymus

Spleen

Removes damaged RBCs, stores iron, and initiates immune responses by B and T cells in response to antigens; contains white and red pulp
Largest lymphatic organ; around 12 cm (5 in.) long and weighs up to 160 g (5.6 oz); lies between 9th and 11th ribs; attached to the lateral border of the stomach by a piece of mesentery (gastrosplenic ligament)

Note