Development of the Face:

1. 28 days after fertilization. The  face develops from five processes: frontonasal, two maxillary, and two mandibular
2. 33 days after fertilization. Nasal placodes, areas of thickening, appear in the frontonasal process.
3. 40 days after fertilization. Maxillary processes extend toward midline. The nasal placodes also move toward the midline and fuse with the maxillary processes to form the jaw and lip.
4. 48 days after fertilization. Continued growth brings structures more toward the midline.
5. 14 weeks after fertilization. Contributions of each process to the adult face.

Functions of the Reproductive System:

1. Production of gametes
2. Fertilization
3. Development and nourishment of a new individual
4. Production of sex hormones

Over approximately 30 days, fluctuations occur in the levels of follicle-stimulating hormone FSH and luteinizing hormone LH secretion from the anterior pituitary gland and in the levels of estrogen and progesterone secretion from the ovary. In addition, changes in the ovary and changes in the endometrium of the uterus are correlated with changes in hormone secretion throughout the menstrual cycle.  Ovulation occurs on about day 14.

The functional unit of the kidney is the nephron and there are approximately 1.3 million of them in each kidney.  Each nephron consists of a renal corpuscle, a proximal convoluted tubule, a loop of hence, and a distal convoluted tubule.  

Urine Formation:

1. Filtration.  Filtration is the movement of materials across the filtration membrane into Bowman's capsule to form filtrate.
2. Tubular Reabsorption.  Solutes are reabsorbed across the wall of the nephron into the interstitial fluid by transport processes, such as active transport and cotransport. Water is reabsorbed across the wall of the nephron by osmosis.  Water and solutes pass from the interstitial fluid into the peritubular capillaries.
3. Tubular secretion. Solutes are secreted across the wall of the nephron into the filtrate.

Filtration Pressure:

1. Glomerular capillary pressure, the blood pressure within the glomerulus, moves fluid from the blood into Bowman's capsule.
2. Capsular pressure, the pressure inside Bowman's cap sure, moves fluid from the capsule into the blood.
3. Colloid osmotic pressure, produced by the concentration of blood proteins, moves fluid from Bowman's capsule into the blood by osmosis.
4. Filtration pressure is equal to the glomerular capillary pressure minus the capsular and colloid osmotic pressures.

Reabsorption in the Loop of Henle: 

1. The wall of the thin segment of the descending limb of the loop of Henle is permeable to water and, to a lesser extent, to solutes.  The interstitial fluid in the medulla of the kidney and the blood in the vasa recta have a high solute concentration.  Water therefore moves by osmosis from the tubule into the interstitial fluid and into the vasa recta. An additional 15% of the filtrate volume is reabsorbed.  To a lesser extent, solutes diffuse from the vasa recta and interstitial fluid into the tubule.
2. The thin segment of the ascending limb of the loop of Henle is not permeable to water but is permeable to solutes.  The solutes diffuse out of the tubule and into the more dilute interstitial fluid as the ascending limb projects toward the cortex.  The solutes diffuse into the descending vasa recta.

Renin and angiotensin help regulate aldosterone secretion.  Renin, an enzyme secreted by cells of the juxtaglomerular apparatuses in the kidneys.  Renin acts on angiotensinogen, a plasma protein produced by the liver, and converts it to angiotensin I.  Angiotensin I is rapidly converted to a smaller peptide called angiotensin II by angiotensin-converting enzyme (ACE). Angiotensin II acts on the adrenal cortex, causing it to secrete aldoesterone.

Aerobic Respiration:

1. Glycolysis in the cytoplasm converts glucose to two pyretic acid molecules and produces two ATP and two NADH. The NADH can go to the electron-transport chain in the inner mitochondrial membrane.
2. The two  pyruvic acid molecules produced in glycolysis are converted to two acetyl-CoA molecules, producing two CO2 and two NADH can go to the electron-transport chain.
3. The two acetyl-CoA molecules enter the citric acid cycle, which produces four Co2, six NADH, two FDH, and two ATP. The NADH and FADH2 can go to the electron-transport chain.
4. The electron-transport chain uses NADH and FADH2 to produce 34 ATP. This process requires O2, which combines with H+ to form H2O.

The Respiratory System is divided into the upper and lower respiratory tract. The upper respiratory tract includes: the external nose, the nasal cavity, the pharynx, and associated structures.  The lower respiratory tract includes: the larynx, the trachea, the bronchi, and the lungs.  

The pharynx is the common passageway for both the respiratory and the digestive system.  Air from the nasal cavity and air, food, and water from the mouth pass through the pharynx.  Inferiorly, the pharynx leads to the rest of the rest of the respiratory system through the opening into the larynx and to the digestive system through the esophagus.  The pharynx can be divided into three regions: the nasopharynx, the oropharynx, and the laryngopharynx. 

The larynx is located in the anterior throat and extends from the base of the tongue to the trachea.  It is a passageway for air between the pharynx and the trachea.  The larynx consists of an outer casing of nine cartilages connected to one another by muscle and ligaments.

The trachea, or windpipe, is a membranous tube attached to the larynx.  It consists of connective tissue and smooth muscle, reinforced with 16-20 C-shaped pieces of hyaline cartilage.

The trachea divides into the left and right main bronchi, or primary bronchi, each of which connects to a lung.  The left main bronchus is more horizontal than the right main bronchus because it is displaced by the heart.  Foreign objects that enter the trachea usually lodge in the right main bronchus, because it is wider, shorter, and more vertical than the left main bronchus and is more in direct line with the trachea. The main bronchi extend from the trachea to the lungs.

The lungs are the principal organs of respiration.  Each lung is cone-shaped, with its base resting on the diaphragm and its apex extending superiorly to a point about 2.5 cm above the clavicle.  The right lung has three lobes, called the superior, middle and inferior lobes.  The left lung has two lobes, called the superior and inferior lobes.  The lobes of the lungs are separated by deep, prominent fissures on the lung surface. 

Pleural Cavities:
The lungs are contained within the thoracic cavity.  In addition, each lung is surrounded by a separate pleural cavity.  Each pleural cavity is lined with a serous membrane called the pleura.  The pleura consists of a parietal and a visceral part.  The parietal pleura, which lines the walls of the thorax, diaphragm, and mediastinum, is continuous with the visceral pleura, which covers the surface of the lung. 

Respiratory Volumes:

1. Tidal Volume- the volume of air inspired or expired with each breath.  At rest, quiet breathing results in a tidal volume of about 500 mL.
2. Inspiratory reserve volume- the amount of air that can be inspired forcefully beyond the resting tidal volume. (about 3000 mL)
3. Expiratory reserve volume- the amount of air that can be expired forcefully beyond the resting tidal volume (about 1100 mL)
4. Residual volume- the volume of air still remaining in the respiratory passages and lungs after maximum expiration (about 1200 mL)

Respiratory Capacities:

1. Functional residual capacity- the expiratory reserve volume plus the residual volume.  This is the amount of air remaining in the lungs at the end of a normal expiration (about 2300 mL at rest)
2. Inspiratory capacity- the tidal volume plus the inspiratory reserve volume.  This is the amount of air a person can inspire maximally after a normal expiration (about 3500 mL)
3. Vital capacity- the sum of the inspiratory reserve volume, the tidal volume, and the expiratory reserve volume.  It is the maximum volume of air that a person can expel from the respiratory tract after a maximum inspiration (about 4600 mL)
4. Total lung capacity- the sum of the inspiratory and expiratory reserves and the tidal and residual volumes (about 5800 mL).  The total lung capacity is also equal to the vital capacity plus the residual volume.

Functions of the Lymphatic System:

1. Fluid Balance
2. Fat absorption
3. Defense

Proliferation of Helper T Cells:

1. Antigen-presenting cells, such as macrophages, phagocytize, process, and display antigens on the cell's surface.
2. The antigens are bound to MHC class II molecules, which present the processed antigen to the T-cell receptor of the helper T cell.
3. Costimulation results from interleukin-1, secrete by the macrophage, and the CD4 glycoprotein of the helper T cell.
4. Interleukin-1 stimulates the helper T cell to secrete interleukin-2 and to produce interleukin-2 receptors.
5. The helper T cell stimulates itself to divide when interleukin-2 binds to interleukin-2 receptors.
6. The "daughter" helper T cells resulting from this division can be stimulated to divide again if they are exposed to the same antigen that stimulated the "parent" helper T cell. This greatly increases the number of helper T cells.
7. The increased number of helper T cells can facilitate the activation of B cells or effector T cells.

The three main types of blood vessels are arteries, capillaries, and veins.  

Arteries- carry blow away from the heart, usually the blood is oxygen-rich.  Blood is pumped from the ventricles of the heart into large, elastic arteries, which branch repeatedly to form progressively smaller arteries.  As they become smaller, the artery walls undergo a gradual tradition from having more elastic tissue than smooth muscle to having more smooth muscle than elastic tissue.  The arteries are normally classified as elastic, muscular arteries, or arterioles, although they form a continuum from the largest to the smallest branches.

Blood flows from arterioles into capillaries, where exchange occurs between the blood and the tissue fluid.  Capillaries have thinner walls than do arteries.  Blood flows through them more slowly, and there are far more of them than of any other blood vessel type.

From the capillaries, blood flows into veins.  Veins carry blood toward the heart; usually, the blood is oxygen-poor.  Compared to arteries, the walls of veins are thinner and contain less elastic tissue and fewer smooth muscle cells. Starting at capillaries and proceeding toward the heart, small diameter veins come together to form larger-diameter veins, which are fewer in number.  Veins increase in diameter and decrease in number as they progress toward the heart, and their walls increase in thickness.  Veins may be classified as venues, small veins, medium-sized veins, or large veins.

Except in capillaries and venues, blood vessel walls consist of three layers, or tunics.  From the inner to the outer wall, the tunics are 1.) the tunica intima, 2.) the tunica media, and 3.) the tunica adventitia, or tunica externa.

Functions of the Heart:

1. Generating blood pressure.
2. Routing blood.
3. Ensuring one-way blood flow.
4. Regulating blood supply.

The right side of the heart pumps blood to the lungs and back tot he left side of the heart through vessels of the pulmonary circulation.  The left side of the heart pumps blood to all other tissues of the body and back to the right side of the heart through vessels of the systemic circulation.

Heart Valves:

The atrioventricular (AV) valves are located between the right atrium and the right ventricle and between the left atrium and the left ventricle.  The AV valve between the right atrium and the right ventricle has three cusps and is called the tricuspid valves.  The AV valve between the left atrium and the left ventricle has two cusps and is called the bicuspid valve or mitral valve.  These valves allow blood to flow from the atria into the ventricles but prevent it from flowing back into the atria.  When the ventricles relax, the higher pressure in the atria forces the AV valves to open and blood flows from the atria into the ventricles.  In contrast, when the ventricles contract, blood flows toward the atria and causes the AV valves to close.  

Each ventricle contains con-shaped muscular pillars called papillary muscles.  These muscles are attached by thin, strong, connective tissue strings called chordae tendineae to the free margins of the cusps of the atrioventricular valves.  When the ventricles contract, the papillary muscles contract and prevent the valves from opening into the atria by pulling on the chordae tendineae attached to the valve cusps.

The aorta and pulmonary trunk possess aortic and pulmonary semilunar valves, respectively.  Each valve consists of three pocket like semilunar (half-moon-shaped) cusps.  When the ventricles contract, the increasing pressure within the ventricles forces the semilunar valves to open.  When the ventricles relax, the pressure in the aorta and pulmonary trunk are higher than in the ventricles.  Blood flows back from the aorta or pulmonary trunk toward the ventricles and enters the pockets of the cusps, causing them to bulge toward and meet in the center of the aorta or pulmonary trunk, thus closing the vessels and blocking blood flow back into the ventricles. 

The epicardium, also called the visceral pericardium, is a thin, serious membrane forming the smooth outer surface of the heart.  It consists of simple squamous epithelium overlying a layer of loose connective tissue and adipose tissue.  The thick, middle layer of the heart, the myocardium, is composed of cardiac muscle cells and is responsible for contraction of the heart chambers.  The smooth inner surface of the heart chambers is the endocardium, which consists of simple squamous epithelium over a layer of connective tissue.  

Conduction System of the Heart:

1. Action potentials originate in the sinoatrial (SA) node and travel across the wall of the atrium (arrows) from the SA doe to the atrioventricular (AV) node.
2. Action potentials pass through the AV node and along the atrioventricular (AV) bundle, which extends from the AV node, through the fibrous skeleton, into the inter ventricular septum.
3. The AV bundle divides into right and left bundle branches, and action potentials descend to the apex of each ventricle along the bundle branches.
4. Action potentials are carried but he Purjinke fibers from the bundle branches to the ventricular walls.

Small electrical changes resulting from action potentials in all of the cardiac muscle cell are recorded by an electrocardiogram (ECG or EKG).  The normal ECG consists of a P wave, a QRS complex, and a T wave. the P wave results from depolarization of the atrial myocardium, and the beginning of the P wave precedes the onset of atrial contraction.  The QRS complex consists of three individual waves: the Q, R, and S waves.  The QRS complex results from depolarization of the ventricles, and the beginning of the QRS complex precedes ventricular contraction.  The T wave represents depolarization of the ventricles, and the beginning of the T wave precedes ventricular relaxation.  A wave representing depolarization of the atria cannot be seen because it occurs during the QRS complex. 

Blood helps maintain homeostasis in several ways:

1. Transport of gases, nutrients, and waste products.
2. Transport of processed molecules.
3. Transport of regulatory molecules.
4. Regulation of pH and osmosis.
5. Maintenance of body temperature.
6. Protection against foreign substances.
7. Clot formation.

The ABO blood group system is used to categorize human blood.  ABO antigens appear on the surface of red blood cells.  Type A blood has type A antigens, type B blood has type B antigens, type AB blood has both types of antigens, and type O blood has neither A nor B antigens.  In addition, plasma from type A blood contains anti-B antibodies, which act against type B antigens; plasma from type B blood contains anti-A antibodies, which act against type A antigens. Type AB blood plasma has neither type of antibody, and type O blood plasma has both anti-A and anti-B antibodies.

Classes of Chemical Messengers:

1. Autocrine chemical messengers- An autocrine chemical messenger stimulates the cell that originally secreted it.
2. Paracrine chemical messengers- Paracrine chemical messengers act locally on nearby cells. These chemical messengers are secreted by one cell type into the extracellular fluid and affect surrounding cells.
3. Neurotransmitters- Neurotransmitters are chemical messengers secreted by neurons that activate an adjacent cell, whether it is another neuron, a muscle cell, or a glandular cell.
4. Endocrine chemical messengers- Endocrine chemical messengers are secreted into the bloodstream by certain glands and cells, which together constitute the endocrine distant from their source.

Functions of the Endocrine System:

1. Metabolism.  
2. Control of food intake and digestion.
3. Tissue development.
4. Ion regulation.
5. Water regulation.
6. heart rate an blood pressure regulation.
7. Control of blood glucose and other nutrients.
8. Control of reproductive functions.
9. Uterine contractions and milk release.
10. Immune system regulation.

Lipid-Soluble Hormones
Lipid- soluble hormones are non polar, and include steroid hormones, thyroid hormones, and fatty acid derivative hormones, such as certain eicosanoids.

Transport of Lipid-Soluble Hormones
Because of their small size and low solubility in aqueous fluids, lipid-soluble hormones travel in the bloodstream attached to binding proteins, proteins that transport the hormones.

Water-Soluble Hormones
Water-soluble hormones are polar molecules; they include protein hormones, peptide hormones, and most amino acid derivative hormones.

Transport of Water-Soluble Hormones
Because water-soluble hormones can dissolve in blood, many circulate as free hormones, meaning that most of them dissolve directly into the blood and are delivered to their target tissue without attaching to a binding protein.

Stimulation of Hormone Release by Humoral Stimuli:
Blood-borne molecules can directly stimulate the release of some hormones. These molecules are referred to as humoral stimuli because they circulate in the blood.  These hormones are sensitive to the the blood levels of a particular substance such as glucose, calcium, sodium. 

Stimulation of Hormone Release by Neural Stimuli:
Following action potentials, neurons release a neurotransmitter into the synapse with the cells that produce the hormone.

Stimulation of Hormone Release by Hormonal Stimuli:
It occurs when a hormone is secreted that, in turn, stimulates the secretion of other hormones.  The most common examples are hormones from the anterior pituitary gland, called tropic hormones.

Nuclear Receptor Model:

1. Lipid-soluble hormones diffuse through the plasma membrane.
2. Lipid-soluble hormones bind to cytoplasmic receptors and travel to the nucleus or bind to nuclear receptors.  Some lipid-soluble hormones bind receptors in the cytoplasm and then move into the nucleus.
3. The hormone-receptor complex binds to a hormone response element on the DNA, acting as a transcription factor.
4. The biding of the hormone-receptor complex to DNA stimulates the synthesis of messenger RNA (mRNA), which codes for specific proteins.
5. The mRNA leaves the nucleus, passes into the cytoplasm of the cell, and binds to ribosomes, where it directs the synthesis of specific proteins.
6. The newly synthesized proteins produce the cell's response to the lipid-soluble hormones- for example, the secretion of a new protein.