Human Anatomy and Physiology
The Cell
The cell is the basic unit of living things. All have a membrane which are semi-permeable and
made up of phospholipids and transport proteins that help molecules and ions move in/out of the cell.
Cells are filled with fluid called cytoplasm or cytosol. Each cell contains organelles which help the cell
survive. Every organelle has its own unique membrane. The larger the cell, the more organelles.
Cell Structural Organization
All cells contain DNA and RNA. They are able to make proteins. All organisms have very
organized structures. Each cell is made up of nucleic acids, cytoplasm, and a cell membrane. Some
organelles are specialized (ex. Mitochondria or chloroplasts). Single-celled organisms have all the
components needed to survive. However, multicellular organisms can have specialized organelles that
serve different functions. Life begs as a single cell (asexual or sexual repro).
● Cells grouped into tissues
● Tissues grouped into organs
● Organs grouped into organ systems
● Organism = complete individual
Nuclear Parts of a Cell
● Nucleus: The defining structure for eukaryotic cells. It regulates DNA and is made up of
chromosomes, chromatin, nuclear envelope, nuclear pores, ribosomes, and nucleolus. It is
responsible for passing traits between generations.
● Chromosomes: highly condensed rods of DNA. DNA is the genetic material that stores info
about the organism
● Chromatin: consists of DNA and protein that make up chromosomes
● Nucleolus: structure in the nucleus that consists of protein. It does not have a membrane and
plays a role in protein synthesis and synthesizes/stores RNA
● Nuclear envelope: encloses the structures inside the nucleus. There is an inner and outer
membrane made of lipids.
● Nuclear pores: involved in exchange of materials between nucleus and cytoplasm
● Nucleoplasm: liquid substance inside the nucleus similar to cytoplasm
Cell Membrane/Plasma Membrane
The thin semi permeable membrane made up of lipids and proteins. The membrane separates the
cell from the environment while still letting it communicate with the environment. It is a phospholipid
bilayer with hydrophilic (likes water) heads that face the outer environment and hydrophobic (hates
water) tails that face each other. Cholesterol is embedded in the cell membrane and adds
stiffness/flexibility to the membrane. Glycolipids help the cell to recognize other cells of the same
organism. Proteins help give the cell its shape. Special proteins help the cell communicate with the
environment. Other proteins transport molecules across the cell membrane.
Selective Permeability
Size, charge, and solubility determine if something can pass through the membrane. Small
molecules are usually able to diffuse. Example, oxygen and water molecules are small and typically pass
through. If a molecule is the same charge, they will be repelled and molecules of different charge are
attracted. Molecules soluble in phospholipids can usually pass through the cell membrane. Many
molecules cannot diffuse through the membrane and require an active transport vesicle.
Cell Structure
● Ribosomes: synthesize proteins from amino acids. Some are mobile in the cell and some are
embedded in RER.
○ Make up ¼ of the cell.
● Golgi: synthesizes materials that are sent out of the cell. Multi-membrane and located near the
nucleus
● Vacuoles: sacs for storage, digestion, and waste removal.
○ Plant cells have one large vacuole vs. animal cells have multiple small ones
● Vesicle: small organelle that helps move materials within a cell
● Cytoskeleton: microtubules that shape/support the cell
● Microtubules: part of the cytoskeleton that are made of protein and shape/support the cell
● Cytosol: liquid inside the cell composed of mostly water and some molecules
● Cytoplasm: refers to the cytosol and organelles in the plasma membrane but not those within the
nucleus
● Cell membrane: the barrier of the cell that helps regulate what goes in/out of the cell.
● Endoplasmic Reticulum (ER): the cell’s transport system that is fused to the nuclear membrane
and extends through the cytoplasm
○ Rough Endoplasmic Reticulum (RER): has ribosomes on the surface
○ Smooth Endoplasmic Reticulum (SER):
● Mitochondria: generates ATP, involved in cell growth/death
○ Contain their own DNA than that of the nucleus
○ Aerobic respiration occurs here
○ Inner and outer membrane
■ Inner membrane encloses the matrix, mitochondrial DNA, and ribosomes
■ Between the membranes are the folds/cristae
● Chemical reactions occur here to release energy, control water levels in the
cells, recycle/create proteins and fats
○ Functions:
■ Cell energy
■ Cell signaling
■ Cellular differentiation - process of cells becoming specialized
■ Cell cycle and growth regulation - process where cells get ready to reproduce
Animal Cell Structure
● Centrosome: made up on pairs of centrioles. Involved in mitosis and cell cycle.
● Centrioles: cylindrical structures near the nucleus that assist in cell division
○ Occur in pairs
○ Each cylinder consist of nine groups of 3 microtubules
● Lysosome: Digests proteins, lipids, and carbohydrates. Transports undigested substances to the
cell membrane for removal. Shape varies.
● Cilia: appendages on the cell surface that help the cell move
● Flagella: tail-like structures on cells that produce whip-like motions to help the cell move.
○ Longer than cilia and not as many
Cell Cycle - process in which cell reproduces
● Cell growth: duplication of genetic material and cell division
● Mitosis: daughter cell is an exact copy of the parent cell
● Meiosis: daughter cells have different genetic coding than parent cell
○ Only in gametes
Cell Differentiation
This is the process of a cell becoming more specialized. It is controlled by the genes of zygote.
The genes tella cell which proteins and pieces to build to specialize it. Example is gastrulation---phase
in embryonic development where cells are organized into germ layers.
● Ectoderm - forms nervous system
● Mesoderm - forms the muscular system
● Endoderm - forms the digestive system
Mitosis
● Interphase - cell prepares for division by replicating DNA and cytoplasm (G1, S, and G2
phases)
● Prophase - chromatin forms chromosomes and nuclear membranes disintegrate. Centrioles move
to opposite sides of the cell and spindle fibers begin to form. <mitotic spindles form front he
cytoskeleton and move chromosomes around.
● Metaphase: spindle fibers move chromosomes to align the center of the cell
● Anaphase: sister chromosomes pull apart and become daughter chromosomes. Grooves appear
in the cell membrane
● Telophase: spindle fibers disappear and the nuclear membrane begins to reform. Chromosomes
become chromatin and the membrane is pinched/invaginates
● Cytokinesis - physical splitting of the cell into 2
Meiosis
● The same steps as mitosis but occurs twice. Remember the steps as PMAT I and II
● During first phase of meiosis, chromosomes cross over to exchange genetic material and tetrads
of chromatids are formed
● Nuclear membrane dissolve
● Homologous pairs are separated to the different poles of the cell
● Result is four daughter cells with different chromosomes that are haploid, containing half of the
parent's DNA.
● Meiosis II is similar to mitosis and is good for genetic diversity
Tissues - 7 categories
● Epithelial - tissues joined together tightly
● Connective - dense, loose, or fatty
○ Protects and binds body parts
○ Ex. bone tissue, cartilage, tendons, ligaments, fat, blood, and lymph
● Cartilage - cushions and provides structural support. Jelly-like and fibrous.
○ Ex. disc between the vertebrae
● Blood - transports oxygen to cells and removes wastes. Carries hormones and defends against
disease.
● Bone - hard tissue that supports and protects soft tissues/organs. The marrow produces RBCs
● Muscle - support and move the body. 3 types --- smooth, cardiac, and skeletal
● Nervous - located in the brain, spinal cord, and nerves
○ Neurons form a network in the body that control responses to changes in the
environment.
○ Some neurons send signals to muscles and glands to trigger responses
Organ and Organ Systems
● 11 major systems: integumentary, respiratory, cardiovascular, endocrine, nervous, immune,
digestive, exrectory, muscular, skeletal, and reproductive
3 Primary Body Planes
● Transverse/horizontal plane: divides body into upper and lower halves
● Sagittal plane: divides the body into right and left sections; runs parallel to midline
● Coronal/frontal plane: divides body into front and back sections
Respiratory System
● Upper respiratory system: nose, nasal cavity, mouth, pharynx, and larynx
● Lower respiratory system: trachea, lungs, and bronchial tree
● Airway: nose, nasal cavity, mouth, pharynx, through, larynx (voice box), trachea, bronchi
○ Lined with cilia that trap microbes and debris and sweep them toward the mouth
● Lungs: structure that holds the bronchi and bronchial network that extend into the lungs into
millions of alveoli.
○ Alveoli allow for the exchange of gases with the blood capillaries around them
○ The right lung has 3 lobes vs the left lung has 2 lobes
○ Lungs are surrounded by the pleural membrane which reduces friction between surfaces
when breathing
● Respiratory muscles: diaphragm and intercostal muscles
○ Diaphragm is dome shaped muscle that separates the thoracic and abdominal cavities
○ Intercostal muscles are located between the ribs
● Function: Supply the body with oxygen and get rid of carbon dioxide.
○ This process occurs at the alveoli which are surrounded by capillaries
○ Warms, moistens, and filters air as it goes through the nasal passages and into the lungs
○ Responsible for speech as air passes through the larynx before it enters the trachea
○ Cough production to rid of foriegn particles in the respiratory system
○ Sense of smell - chemoreceptors located into the nasal cavity react to chemicals in the air
○ Maintain acid-base homeostasis
■ Hyperventilation increase pH during acidosis (low pH)
■ Slow breathing during alkalosis (high pH) helps lower blood pH
● Breathing Process
○ Controlled by medulla oblongata which monitors CO2 levels in the blood
○ Diaphragm and intercostal muscles contract to expand the lungs
○ Inspiration - diaphragm contracts and moves down and intercostal muscles contract to
expand ribs to increase size of chest cavity
■ Volume of chest cavity increases and pressure decreases
○ Expiration - diaphragm and intercostal muscles relax.
Circulatory System
● Responsible for internal transport of substances to/from cells
○ 3 parts:
■ Blood - composed of water, solutes, and other elements in a fluid connective
tissue
■ Blood vessels - tubules of different sizes that transport blood
■ Heart - pumps blood and provides pressure to keep blood flowing
● This system can be either open or closed, but most animals have closed systems where the heart
and vessels are alway connected
○ Capillary bed blood flow tends to be very slow
● Lymph vascular system - cleans up excess fluids and proteins then returns them to the
circulatory system
● Blood
○ Helps maintain a healthy internal environment by carrying raw materials to cells,
removing waste, and stabilizes pH
○ Blood is made up of red and white blood cells, platelets, and plasma (mostly water and
makes up over half the blood volume)
■ Plasma contains proteins, ions, glucose, amino acids, hormones, and dissolved
gases.
○ RBCs transport oxygen to cells
■ Form in the bone marrow and are constantly being replaced
○ WBCs defend against infection and remove waste
■ Ex. lymphocytes, neutrophils, monocytes, eosinophils, and basophils
○ Platelets are fragments of stem cells that help in blood clotting
● Heart
○ Made of cardiac muscle tissue and 4 chambers. The halves are separated by valves which
prevent backflow of blood into the chambers
○ Has its own circulatory system and coronary arteries
○ Cardiac cycle:
■ Atrial contraction - fills ventricles
■ Ventricular contraction - empties ventricles and forces circulation
○ Cardiac cells produce their own electric signals and are self-exciting
Cardiac Cycle
● First diastole
○ Blood flows through the SVC and IVC into the right atrium and through the
atrioventricular/tricuspid valve towards the right ventricle
○ SA node (pacemaker of the heart) in the right atrium generates electrical signals that are
carried by the purkinje fibers to the rest of the atrium stimulating it to contract and fill the
right ventricle with blood
● First Systole
○ The signals from the SA node are carried to the AV node which signals the right ventricle
to contract and starting first systole
○ Tricuspid valve closes and pulmonary semilunar valves open
○ Blood is pumped out of the pulmonary arteries to the lungs
● Second diastole
○ Blood from the lungs fills the left atrium
○ SA node triggers mitral valve to open and blood fills the left ventricle
● Second systole
○ Mitral valve closes
○ Aortic semilunar valve opens
○ Left ventricle contracts and blood is pumped out of aorta and into the body
Types of Circulation
● Coronary circulation - blood flow to the heart tissue
○ Blood enters the coronary arteries which supply major arteries with oxygenated blood
○ Deoxygenated blood returns to the right atrium through cardiac veins that empty into the
coronary sinus
● Pulmonary circulation - flow of blood between heart and lungs
○ Deoxygenated blood flows from the right ventricle into the lungs through pulmonary
arteries
○ Oxygenated blood flows back to the left atrium through pulmonary veins
● Systemic circulation - flow of blood to entire body with exception to the coronary and
pulmonary circulations
○ Blood leaves the left ventricle through the aorta which branch into many arteries and
empty into the SVC and IVC
● Portal circulation - flow of blood from digestive system to the liver and then the heart
● Renal circulation - flow of blood between the heart and kidneys
Blood pressure - Fluid pressure generated by the cardiac cycle
● Arterial blood pressure - transports oxygen poor blood to the lungs and oxygen rich blood to
the body tissues
○ Arteries branch into arterioles which contract/expand based on signals
○ Arterioles assist in blood delivery to specific areas
● Capillary beds - sites of diffusion between blood and interstitial fluid
○ Thinnest walls and made of single layer of endothelial cells
○ Capillaries merge into venues that merge with tubules/veins
○ Veins transport blood from body tissues back to the heart
■ Valves and veins control this transport
■ Walls of veins are thin and made of smooth muscle
■ Blood volume reserve
Lymphatic System
● Function: return excess tissue fluid to the bloodstream
● Consists of transport vessels, lymphoid organs, lymph capillaries, lymph ducts
● Major functions:
○ Return excess fluid to blood
○ Return protein from capillaries
○ Transport fats from digestive tract
○ Disposal of debris and cellular waste
● Lymphoid organs
○ Lymph nodes, spleen, appendix, adenoids, thymus, tonsils, and small patches of tissue in
the small intestine
■ Lymph nodes found in intervals in the lymph vessel system
■ Each lymph node has lymphocytes and plasma cells
■ Spleen filters and stores RBCs and macrophages
■ Thymus secretes hormones and is site of lymphocyte production
● Spleen
○ Major function: filter unwanted materials from blood and fight infection
○ In the upper left abdomen and behind the stomach
○ Made up on lymphoid tissue
○ Blood vessels are connected via the splenic sinuses and peritoneal ligaments support the
spleen
■ Gastrolienal ligament connects stomach to spleen
■ Lienorenal ligament connects kidney to spleen
■ Phrenicocolic ligament connects left colic flexure to diaphragm
Gastrointestinal System
● Major functions:
○ Movement - mixes and passes nutrients through the system and eliminates waste
○ Secretion - enzymes, hormones, and other substances for digestion are secreted into the
digestive tract
○ Digestion - chemical breakdown of nutrients into smaller units that enter the internal
environment
○ Absorption - passage of nutrients through membranes into the blood or lymph, then to the
body
● Mouth and Stomach
○ Mouth - Digestion begins with mastication/physical digestion through chewing and
mixing with saliva. The salivary glands are stimulated to receive saliva, which contains
enzymes that start breakdown of starch. When food is swallowed, it passes through the
pharynx and the esophagus
○ Stomach - a muscular/flexible sac whose main functions are: mixing/storing food,
dissolving/degrading food via secretions, and controlling food passage into the small
intestine. Protein digestion begins in the stomach. Stomach acid helps break down the
food for nutrient absorption. Smooth muscles move food through peristalsis which
contract and relax to move nutrients into the small intestine where absorption begins.
● Liver
○ The largest organ and largest gland in the body. It is made up of 4 lobes (right, left,
quadrate, and caudate lobes). It is supported by 5 ligaments (falciform, coronary, right
triangular, left triangular, and round ligaments). The liver processes all blood that passes
through the digestive system. The functional units are lobules and blood enters the
lobules through the portal vein and hepatic artery. Blood flows through the small
channels via sinusoids.
■ Nutrient rich blood is supplied via the hepatic portal vein.
■ Oxygen rich blood is supplied by the hepatic artery.
■ Blood leaves the liver via the hepatic veins.
The main role of the liver includes:
● Bile production
● Blood plasma protein production
● Cholesterol production (some carry fats)
● Storage of excess glycogen (can be converted to glucose when needed)
● Regulage amino acids
● Process hemoglobin (to store iron)
● Convert ammonia to urea (excreted as urine)
● Blood purification (get rid of drugs/toxins)
● Regulate blood clotting
● Control infections through boosting immune factors and removing bacteria
● Small Intestine
○ Most nutrients are absorbed in the small intestines. Enzymes from the pancreas, liver, and
stomach are all transported here to help with digestion. These enzymes help break down
fats, carbs, nucleic acids, and proteins. Bile is secreted by the liver and is good for
breaking down fats. Bile is stored in the gallbladder. When food reaches the small
intestine, it is now small molecules. The lining of the small intestine is made up of villi,
which are tiny absorptive structures that increase surface area for chime interaction.
Epithelial microvilli located on villi help increase surface area and increase ability to the
small intestine to be the main absorption organ of the digestive tract.
● Large Intestine/colon
○ This organ concentrates, mixes, and stores waste material. It is attached to the rectum and
when the rectal wall is distended by waste, the sphincter at the end of the anus will expel
the waste. Speed at which waste is moved depends on the volume of fiber and other
undigested materials.
● Pancreas
○ The pancreas is made of both exocrine and endocrine tissues. The exocrine tissues secrete
digestive enzymes from ducts that form the main pancreatic duct. This duct connects to
the common bile duct. Endocrine tissue secretes hormones (ex. insulin) into the blood.
Blood is supplied to the pancreas via the splenic, gastroduodenal, and superior mesenteric
arteries. The pancreas helps with digestion by secreting enzymes to the small intestine
that help break down foods, esp fats and proteins. The precursors to these enzymes are
called zymogens and are produced by acinar exocrine cells. They are converted into the
gut into active enzymes (ex. Pancreatic lipase and amylase) once in the small intestine.
The pancreas also secretes sodium bicarbonate to neutralize stomach acid that reaches the
small intestine. Exocrine functions of the pancreas are controlled by hormones released
by the stomach and duodenum when food is present. These secretions flow into the main
pancreatic duct (Wirsung’s duct) and make its way to the duodenum via the pancreatic
duct.
Nervous System
The role of this system is to sense, interpret, and issue commands in response to the body’s
environment. The communication of this system is made up of neurons. Messages sent across the
plasma membrane through action potentials. APs occur when neurons are stimulated past their
threshold. Upon chemical synapse, neurotransmitters are released that stimulate/inhibit the action of the
neighboring cell. The flow of the impulse depends on the organization of the nerves.
● Types of neurons
○ Sensory neurons: send signals from the sensory receptors to the CNS
○ Motor neurons: send signals from the CNS to the rest of the body (ex. Muscles, glands)
○ Interneurons: send signals between neurons (ex. Interneurons exist between sensory and
motor neurons)
● Anatomy of a neuron
○ Dendrites - receive impulses from sensory receptors or interneurons and send them to the
cell body (soma)
○ Cell body (soma) - contains the nucleus of the neuron
○ Axon - transmits impulse away from the cell body towards the axon terminals and
terminates at the synapse
○ Myelin sheath - the insulation of the axon made up of oligodendrocytes
○ Nodes of Ranvier - gaps in between the sheath that the impulse bounces off of
Central Nervous System
The CNS is made up of the brain and spinal cord. The spinal cord is encased in the vertebrae
which protect and support it. Its tissue functions for limb movement and internal organ activation. The
nerve tracts ascend/descend from the spinal to the brain. The brain is made up of the following:
● Hindbrain --- medulla oblongata, cerebellum, and pons
○ Cerebellum: process/store implicit memories, classical conditioned learning techniques
○ Brain stem: made up on the midbrain, pons, and medulla oblongata
■ Respiratory, digestive, and circulatory function
○ Medulla oblongata: connects brain to spinal cord and assists with ANS in circulatory
and respiratory systems
● Midbrain --- tectum, tegmentum, and ventral tegmentum
○ Integrates sensory signals and responses
○ Vision and hearing
● Forebrain --- cerebrum, thalamus, and hypothalamus
The cerebral cortex is a thin layer of gray matter that covers the cerebrum. The brain is split into 4 lobes
(frontal, parietal, occipital, and temporal lobes)
● Frontal lobe: short term memory, working memory, information processing, decision making,
planning, and judgement
● Parietal lobe: sensory input, spatial positioning of the body
● Occipital lobe: visual input, processing, and output
● Temporal lobes: auditory input, processing, and output
The Peripheral Nervous System is made of the nerves and ganglia in the body including the SNS (fight
or flight) and PNS (rest and digest) which control basic body function
Autonomic Nervous System
The ANS maintains homeostasis in the body. It controls internal organs, blood vessels, smooth
muscle tissue, and glands. The hypothalamus controls the ANS through the brainstem and helps
maintain a stable environment by regulating heart rate, breathing, body temp, and blood pH. There are 2
divisions of the ANS --- sympathetic and parasympathetic. The sympathetic nervous system controls the
body’s reaction to extreme situations (fight or flight) by increasing heart rate, secreting adrenal
hormones, dilating the eyes, slowing digestion. The parasympathetic nervous system does the opposite.
Somatic Nervous System and Reflex Arc
The SNS controls the five senses and voluntary movement of skeletal muscle. Afferent (sensory),
efferent (motor), and the neurons connected to sense organs help operate the senses and move the
muscles.
● Afferent - brings signals from sensory organs/muscles to the CNS
● Efferent - bring signals from CNS to the sensory organs/muscles
Reflex arcs are the simplest nerve pathway of the nervous system. It is an automatic response that
bypasses the brain and is controlled by the spinal cord. The stimulus is detected by sensory receptors →
sensory neurons → interneurons in the spinal cord → motor neuron → effector muscle/gland
Muscular System
There are three types of muscle tissue --- skeletal, cardiac, and smooth --- and they all have the
same 3 properties:
● Excitability: all muscle tissues have an electric gradient that can reverse when stimulated
● Contraction: contract or shorten
● Elongate: can elongate or relax
Types of Muscular Tissue
● Skeletal muscle: voluntary muscles that work in pairs
○ Composed of muscle fibers that are bound in bundles
○ Striated appearance
○ Attach to bone and transmit force to the bone
● Smooth muscle: involuntary muscles that are found in walls of internal organs
○ Also known as visceral tissue
○ Non-striated appearance, smoother and wider than skeletal muscle fibers
○ Found in sphincters or valves
● Cardiac muscle: involuntary muscle found in the heart
○ Striated appearance
Skeletal Muscle Contraction
Every skeletal muscle is made up of numerous fibers and each fiber has bundles of myofibrils.
Myofibrils are composed of multiple repeating contractile units called sarcomeres. The myofibrils have
thick (myosin) filaments and thin (actin) filaments. Muscle contraction occurs when the thin filaments
slide over thick filaments, thus shortening the sarcomere. When an AP reaches a muscle fiber, calcium
ions are released and bind to the myosin and actin. This helps the myosin heads bind to the actin
molecules. ATP is released from glucose to provide energy.
Reproduction System
The male reproductive system’s main job is to produce/maintain/transfer sperm and semen, and
produce male hormones. The external structures are the penis, scrotum, and testes. The penis contains
the urethra which can fill with blood and become erect in order to release semen and sperm. The
scrotum is a sac or skin and smooth muscle that house the testes. Its job is to keep the testes at a proper
temperature for spermatogenesis. The testes are the male gonads where sperm and testosterone are
produced. The internal structure includes the epididymis, vas differences, ejaculatory ducts, urethra,
seminal vesicles, prostate gland, and bulbourethral glands. The epididymis stores sperm until
maturation. Mature sperm then moves from the epididymis to the vas differences than to the ejaculatory
duct. The seminal vesicles secrete alkaline fluids with protein and enzymes into the ejaculatory duct.
The prostate gland secretes white fluid with enzymes and proteins as part of semen. The
bulbourethral/cowper’s gland secretes fluid into the urethra to neutralize the acidity of the urethra. The
hormones associated with the male repro system are follicle stimulating hormone (FSH) which stimulate
spermatogenesis and luteinizing hormone (LH) which stimulates testosterone production. Testosterone is
responsible for male sex characteristics.
The female reproductive system’s job is to produce ova, transfer them to the fallopian tubes,
receive sperm, and to provide a good environment for an embryo. The external portion include the
labias, bartholin’s gland, and clitoris. The labia protects the vagina. The bartholin's glands secrete
lubricating fluid. The clitoris has erectile tissue with nerves that serve the purpose for pleasure. The
internal portion includes the ovaries, fallopian tubes, uterus, and vagina. The ovaries are the female
gonads and produce ova and secrete estrogen/progesterone. The fallopian tubes carry the mature egg
toward the uterus. If an egg is fertilized it will implant in the uterine wall. The vagina is a muscular tube
that extends from the cervix to the outside of the body. It receives the semen and sperm, and functions as
the birth canal.
Integumentary System
Consists of the skin, sebaceous glands, sweat glands, hair, and nails. It provides protection,
secretion, and communication. The skin helps protect against pathogens. The sebaceous glands secrete
sebum to waterproof the skin and sweat glands help with thermoregulation. Sweat glands are also
excretory organs who help rid of metabolic wastes. Sensory receptors in the skin help provide info to the
brain about pain, touch, pressure, and temperature. The skin also manufactures vitamin D and can
absorb certain chemicals and medications.
● Skin layers
○ Epidermis: most superficial layer consisting of epithelial cells and no blood vessels
■ Stratum basale is the deepest layer of the epidermis and is continuously
undergoing division. Older cells are pushed toward the service.
■ Most epidermal cells are keratinized in a waxy protein to help waterproof the skin
○ Dermis: mostly connective tissue, blood vessels, sensory receptors, hair follicles,
sebaceous glands, and sweat glands. Also contains elastin and collagen fibers.
○ Hypodermis: technically not a layer of skin, but contains connective tissue that binds to
the skin of underlying muscles. Fat here helps cushion and insulate the body.
● Skin and Homeostasis
○ Thermoregulation is accomplished through sweat glands. This is a negative feedback
system where the receptors are the sensory cells in the skin, the control center is the
hypothalamus, and the effectors are the sweat glands, blood vessels, and muscles.
Evaporation of sweat on the skin helps cool the body. Vasodilation of the blood vessels
releases heat to lower body temperature. Shivering helps increase body temperature.
● Sebaceous vs. Sweat glands
○ Both glands are exocrine glands found in the skin because they secrete substances into
ducts. Sebaceous glands are holocrine glands that secrete sebum which is an oil mixture
of lipids and proteins. These glands are connected to hair follicles and secrete sebum
through hair pores. The sebum inhibits water loss and protects against bacterial/fungal
infections. Sweat glands are either eccrine or apocrine glands. Eccrine glands are not
connected to hair follicles and are activated by increased body temperature. They secrete
salty electrolytes and water containing NaCl, K, bicar, glucose, and antimicrobial
peptides. Apocrine glands secrete oily solution of fatty acids, triglycerides, and proteins.
They are located in the armpits, groin, palms, and feet soles. They secrete oily sweat and
bacteria feed on this and cause body odor.
Endocrine System
This system is responsible for secreting hormones and molecules that will help regulate the entire
body. The hypothalamus and pituitary gland coordinate to serve as neuroendocrine control centers.
Hormone secretion is triggered by hormonal signs, chemical reactions, and environmental cues. Only
cells with receptors for the hormones can benefit. Steroid hormones trigger gene activation and protein
synthesis. Protein hormones change activity of enzymes in target cells, Some hormones are fast acting
like insulin while others are slow and can have longer, gradual, or permanent effects.
●
8 major endocrine glands
○ Adrenal cortex - monitors blood sugar level, lipid and protein metabolism
○ Adrenal medulla - controls cardiac function, raises blood sugar, controls size of blood
vessels
○ Thyroid gland - regulates metabolism and functions in growth and development
■ Thyroxine: increase metabolism
■ Triiodothyronine: increase metabolism
■ Calcitonin: decreases blood calcium by storing calcium in bone tissue
○ Parathyroid - regulates calcium levels in blood
■ Located in the neck with four small glands on the posterior side of the thyroid
gland
■ Parathyroid hormone which can increase blood calcium by moving calcium from
bone to blood
○ Pancreas islets - raise/lowers blood sugar, carbohydrate metabolism
■ Islets of langerhans (endocrine cells) that are made of insulin-producing beta
cells and glucagon releasing alpha cells. They produce insulin and glucagon.
● Insulin is used to lower blood sugar and affects fat metabolism
● Glucagon is used to increase blood sugar
○ Thymus gland - role in immune response
○ Pineal gland - daily biorhythms and sexula activity
○ Pituitary gland - role in growth and development
■ Hypothalamus tells it to secrete TSH which stimulates the thyroid gland to release
the thyroid hormones via a negative feedback system
Urinary System
Its job is to eliminate excess substances while preserving what the body needs. This system
consists of the kidneys, ureters, and bladder. The kidneys consist of three layers --- renal cortex (outer),
renal medulla (inner), and renal pelvis (innermost). The renal cortex has nephrons which are the filters
of the kidneys. Each nephron has a glomerulus surrounded by a Bowman’s capsule. Kidneys receive
blood from the renal arteries. They generally filter blood, reabsorb what they need, and secrete
waste/excess water into the urine. The glomerular filtrate enters the proximal convoluted tubule where
water, glucose, ions, and organic molecules are reabsorbed into the bloodstream. Things like urea and
drugs are removed from the blood at the distal convoluted tubule. Blood pH can be adjusted through
secretion of H+ ions. Unabsorbed things flow to the collecting tubules in the renal medulla to the renal
pelvis as urine where it is drained to the kidneys via the ureters to the bladder where it is stored till
expulsion through the urethra.
Immune System
Protects the body against pathogens and includes the lymphatic system, red bone marrow, and
leukocytes. Lymph capillaries combine to form lymph vessels and skeletal muscle contracts to move
lymph through the ducts which eventually return to the venous blood in lymph nodes. These lymph
nodes filter lymph of pathogens and other matter. Lymph nodes are concentrated in the neck, armpits,
and groin area. The tonsils are made of lymph tissues and help protect against pathogens entering
through the mouth. The thymus serves as a maturation place for immature T cells that are made in the
bone marrow. The spleen cleans blood of dead cells and pathogens. THe peyer’s patch in the small
intestine protects the digestive system from pathogens. The body's general immune defense include:
● Skin: intact epidermis and dermis form a barrier against pathogens
● Ciliated mucous membranes: cilia sweep pathogens out of the respiratory tract
● Glandular secretions: gastric acid destroys pathogens
● Normal bacteria population: compete with pathogens in gut and vagina
Phagocytes and inflammation mobilize WBC and chemical reactions to stop infection (ex. Localized
redness, tissue repair, fluid seeping healing agents). Plasma proteins repel bacteria and pathogens. Types
of WBC:
● Macrophage: phagocytes that alert T cells to presence of foriegn substances
● T lymphocytes: directly attack cells infected
● B lymphocytes: target specific bacteria for destruction
Types of Leukocytes/WBCs
● These are produced in the red bone marrow
● Monocytes (macrophages, dendritic cells) - found in lymph and are the largest/long-living
○ Engulf and destroy pathogens
○ Dendritic cells present antigens to T cells
● Granulocytes (neutrophils, basophils, eosinophils)
○ Neutrophils - short lived phagocytes that respond quickly to pathogens
○ Basophils - alert the body of infection
○ Eosinophils - large, long living phagocytes that defend against multicellular invaders
● T lymphocytes
○ Helper T cells: help body fight infection by producing antibodies and other chemicals
○ Killer T cells: destroy infected cells
○ Suppressor T cells: stop or suppress other T cells when the infection is over
○ Memory T cells: remain in the blood on alert incase the infection comes back
● B lymphocytes - produce antibodies
Antigen and Typical Immune Response
Antigens stimulate the immune response and are typically proteins on the surfaces of pathogens.
Drugs, toxins, and foreign particles can also be antigens. Specific antibodies are produced after each
antigen exposure. The antigen is engulfed by a macrophage which presents the fragment on its surface.
A helper T cell joins the macrophage and the Killer T and B cells are activated. The Killer T will seek
out cells with the same antigen and destroy them. B cells differentiate into plasma cells and memory
cells. Plasma cells produce antibodies specific to the pathogens. These antibodies bind to the surface of
an antigen and mark them for destruction. Memory cells help protect against future infection.
Immunity
● Naturally acquired active immunity: individual is exposed and builds immunity to a pathogen
without an immunization
● Artificially acquired active immunity: individual exposed and builds immunity by a vaccine
● Naturally acquired passive immunity: happens during pregnancy where antibodies are
transferred either through bloodstream or through breast milk.
○ This is temporary protection till childhood
● Artificially acquired passive immunity: an immunization is given after recent outbreaks.
○ Short lived and quick
Skeletal System
Made up on bones and cartilage, there are 206 bones. The skeletal system is divided into the:
● Axial skeleton (80 bones) - skull, sternum, ribs, vertebral column, and hyoid bones
○ Vertebral column has 33 vertebrae
○ Rib cage: 10 pairs of true ribs, 2 pairs of floating ribs, and sternum
○ Skull: cranium and facial bones
○ Ossicles: bone of middle ear
○ Hyoid bone: attachment for tongue muscles
○ These bones protect the vital organs
● Appendicular skeleton (126 bones) - arm bones, feet, hands, legs, hips, and shoulder
○ Pectoral girdle: scapula, clavicles
○ Pelvic girdle: pelvic bones
○ Appendages: the bones of the upper and lower extremities
● Functions:
○ Movement: move bones of the body
○ Mineral storage: store essential mineral ions
○ Support: bones are the framework and support system for the organs
○ Protection: bones surround and protect key organs in the body
○ Blood cell formation: RBCs are formed in the marrow of certain bones
Bones are connective tissue containing collagen and living cells. Bone cells are constantly
regenerating, but this regeneration can deteriorate with age and lead to osteoporosis. The backbone is
supported by muscles and ligaments while the intervertebral column has discs which cushion the
vertebrae, however damage can lead to disc herniation. Joints are areas of contact and include:
● Synovial joints: most common and freely moveable (ex. Knees and shoulders)
● Cartilaginous joints: fill the space between bones to restrict movement (ex. Intervertebral discs)
● Fibrous joints: have fibrous tissue connecting bones with no cavity
There are 2 types of bone tissue: compact and spongy. Compact/cortical bone is tightly packed, strong,
dense, and rigid. It contains haversian canals surrounded by concentric circles called lamellae. The
spaces between the lamellae are lacunae. The lamellae and canals contain arteries, veins, lymph vessels,
and nerve endings. This is the haversian system that is a reservoir for calcium and phosphorus for the
blood. Spongy/cancellous bone is made up of trabeculae which are a network of spaces filled with red
bone marrow. Spongy bone is more lightweight and porous which helps reduce the bone’s overall
weight.The diaphysis of bone contains compact bone surrounding the marrow cavity while the epiphysis
contains spongy bone with red marrow which produces RBCs and WBCs.
Macromolecules
These are large and complex molecules. The four macromolecules are: carbohydrates, nucleic
acids, proteins, and lipids The four basic building blocks are: monosaccharides, amino acids, fatty acids,
and nucleotides. Anabolic reactions require energy to build larger complex molecules from smaller ones
while catabolic reactions release energy to break down large molecules into smaller ones.
● Endothermic reactions absorb heat
● Exothermic reactions release heat
Carbohydrates
Carbs are the primary source of energy and are easily converted into glucose. Glucose can be
further broken down through respiration or fermentation through glycolysis. Glucose can also be used in
photosynthesis. Carbohydrates are broken down into sugars or glucose.
● Simple sugars: mono and disaccharides
Lipids
Also known as fat, they are soluble in nonpolar solvents but are hydrophobic. Their major role is
energy storage and structural functions. Examples are fats, phospholipids, steroids, adn waxes.
Triglycerides are made of long chains of fatty acids. Fatty acids are chains with reduced carbon at one
end and a carboxylic acid group at the other end. Phospholipids are lipids with a phosphate group
instead of a fatty acid. Glycerides are formed from fatty acids and glycerol.
Proteins
These are the macromolecules formed from amino acids. They are polypeptides that are formed
in a condensation reaction where water is lost to join two molecules. A hydrolysis reaction is when
water is added to form a peptide. A peptide contains two or more amino acids. Amino acids are formed
through parietal hydrolysis of protein which forms an amide bond. In a carbon chain of amino acid there
is a carboxylic acid group, amino group, central carbon atom, and R group which determines the
property of the protein.
Enzymes
A type of protein that is a catalyst. It accelerates the speed of a reaction so that it happens faster
and more often. Each enzyme deals with reactants and substrates. Enzymes may need to reshape
themselves to fit with their substrates. THey are not permanently consumed when used and can be used
again as a constant source of energy.
Nucleic Acids
These are the macromolecules that make up nucleotides. Hydrolysis breaks the RNA and DNA
(oligonucleotides) into shorter strands. Oligonucleotides are broken down into nitrogenous units called
nucleosides. These can be digested by the cell to form 5 nitrogenous bases. RNA and DNA are formed
by nucleotides joined by phosphodiester bonds. Nitrogen fixation is used to make nucleotides from
DNA and amino acids from proteins. Nucleic acids store info and energy and are important catalysts.
RNA catalyzes the transfer of DNA into protein coded info. ATP is an RNA nucleotide. Nucleotides are
made of 5-carbon sugar, nitrogenous base, and one or more phosphates. The bond with phosphate can
store energy.
DNA
Chromosomes are made of genes and genes are simple units of genetic info. Genes are made of
DNA which is a nucleic acid found in the nucleus. There is also DNA in mitochondria. DNA is a double
helix structure where there is a sugar-phosphate backbone and rungs of nitrogenous bases (adenine,
thymine, cytosine, guanine). These bases can be categorized as pyrimidines and purine bases.
Pyrimidines contain a single ring and are C, T, and U. Purines contain two rings and are A and G.
Codons are groups of three nucleotides which code for a single amino acid. There are 64 codons but 20
amino acids. There are start codons (AUG/Methionine) and stop codons (UAA, UGA, UAG).
DNA Replication
DNA is unwound by helicase into two strands. The origin of replication is where the splitting of
the DNA strand starts. Each strand of DNA is transcribed by an mRNA to make a complementary copy
of DNA where uracil replaces thymine. mRNA carries a strand of DNA and transports it from the
nucleus to the cytoplasm. Transcription is the process where RNA Pol copies DNA into RNA.
Translation is the process where ribosomes use RNA to put together the protein and is done by tRNA.
RNA vs. DNA
● RNA = ribose vs. DNA = deoxyribose
● RNA = AUGC vs. DNA = ATCG
Non-Mendelian Concepts
● Codominance: expression of both alleles so that both traits are shown
● Incomplete dominance: both dominant and recessive genes are expressed as a mixture of the
two
● Polygenic inheritance: traits are influenced by more than one gene and environmental
influences of development
● Multiple alleles: a gene with at least 3 possible alleles
Chemistry
● Atomic number = number of protons
● Atomic mass = total number of protons + neutrons
● Radioactive isotopes: unstable nuclei makes them at risk for spontaneous nuclear reactions and
emit radiation
● Electrons
○ Stable = all electrons in lowest available position
○ Outermost electron = valence electron which determines bonding behavior
● Chemical bonds
○ Ionic bonding: transfer of electrons from one atom to another
■ Atoms lose or gain electrons are called ions
○ Covalent bonding: sharing of one or more pairs of electrons
■ Strong and occur most frequently between atoms of similar electronegativities
■ Nonmetals are likely to form covalent bonds
○ Hydrogen bonds
■ The weakest of the bonds
■ Water is a good example because it is partially positive AND negative
■ Important in proteins, nucleic acids, and DNA
Diffusion and Osmosis
● Passive transport
○ Simple diffusion: particles flow from high to low concentration till equilibrium is reached
○ Facilitated diffusion: occurs when specific molecules are transported by a specific carrier
protein
■ Carrier proteins vary in shape and charge
■ Ex. glucose and amino acids need carrier proteins
○ Osmosis: diffusion of water through semi-permeable membrane from area of low to high
solute concentration
■ Cells that swell due to water retention = turgid