Human Anatomy.

Human Anatomy

Levels of Organization
Cells Tissue Organ Organ System Smallest Unit of Life A group of cells working together A group of tissues working together A group of organs working together

4 Types of Body Tissue Muscle tissue- composed of cells that contract.
Movement is the result of muscle tissues contracting in a coordinated fashion Nervous tissue- contains cells that receive and transmit messages in the form of electrical impulses Epithelial tissue- layers of cells that line or cover all internal and external body surfaces Often provides a protective barrier Your skin is epithelial tissue

4 Types of Body Tissue Connective tissue- binds, supports, and protects structures in the body Most abundant and diverse type of tissue Includes Bone, Cartilage, Tendons, Fat, and Blood Connects or holds things together, such as groups of muscles Characterized by large cells that are embedded in large amounts of an intercellular substance called matrix

Body Systems: (YOU WILL NEED YOUR BOOK FOR THE DIAGRAMS)
When organs work together to complete a specific task, it is called an Organ System There are many organ systems in your body: Skeletal Circulatory Muscular Respiratory Integumentary(skin) Reproductive Digestive Endocrine Immune Excretory Nervous

Body Cavities (p. 910) When discussing organ systems, many of them are located in “compartments” in the body called cavities. Cranial cavity: contains the brain Spinal cavity: surrounds the spinal chord Thoracic cavity: contains heart, lungs and organs of the respiratory system Abdominal cavity: contains organs of digestive system Diaphragm: separates abdominal and thoracic cavity Pelvic cavity: contains organs of reproduction and excretion

Skeletal This system provides support for the entire body
Ribs protects our vital organs-like your heart and lungs The spine is the central support for the body. The longest bone in your body is your femur

Skeletal Your hands and feet are so flexible because they are made of MANY bones: Each foot has 26 bones, while each hand has 27 bones That means that over half your bones are found in your hands and feet!!!

Skeletal (p.911) Axial Skeleton
skull, rib cage, spine (backbone), sternum Appendicular Skeleton arms, legs, pelvis, scapula, and clavicle (shaded in on picture)

Joints (p. 915) The place where two bones meet is called a joint
Fixed joints: prevent movement. Often connective tissue is located in a fixed joint to absorb impact. Example: skull Semimovable joints: give limited movement. Generally allow enough movement to absorb shock or impact Example: spinal chord Moveable joints: allow a wide range of motion. Example: knees, shoulders

Joints (p. 916) Joints that are subject to a lot of pressure (like your knees) are cushioned and protected from friction (which would damage the bones) by cartilage and synovial fluid (also called synovial sac). They connect to the bone with ligaments Cartilage: connective tissue located between moveable bones. Acts as a surface to reduce friction and wear. Ligaments: tough connective tissue that hold the bones of a joint in place Synovial fluid : fluid secreted that lubricates the bones of the joint to reduce friction and wear

Joints Two painful conditions can exist at the joints:
Rheumatoid arthritis: immune system attacks the body at the joints. Causes inflammation, swelling and stiff joints Osteoarthritis: cartilage begins to wear thin. The bones begin to rub together and causes severe discomfort

Bone anatomy (p. 912) While your bones are hard on the outside (compact bone and periosteum), they are soft on the inside (spongy bone). Periosteum: tough membrane that covers the surface of the bone (where a lot of nerves are) Compact bone: located beneath the periosteum. You’re hard bone is stronger and lighter than steel!!

Bone anatomy (p.912) Beneath compact bone is an area of connective tissue called spongy bone or soft tissue called bone marrow. Spongy bone: strong bone lattice that is located at points of physical stress Bone marrow: serves as a production center for blood cells or an energy reserve Red bone marrow: produces red blood cells, white blood cells, platelets (blood cells don’t have nuclei to perform mitosis) Yellow bone marrow: mostly fat cells that serve as an energy reserve

Internal structure of compact bone (p. 913)
The structure of bone material Bone is made primarily of cylindrical pieces made of mineral and protein called lamellae When young, your bones are made of cartilage that eventually harden to bone (ossification) In the central cylinder of the lamella is a channel called the Haversian canal These channels are where the blood vessels bring nourishment and carry away wastes. Surrounding each Haversian canal is a layer of proteins and bone cells (osteocytes)

Muscular Muscles are responsible for your body's every move.
There are 3 types of muscles: Skeletal Smooth Cardiac

Skeletal Muscle Skeletal muscles move and support the skeleton.
There are 640 individually named skeletal muscles. When these muscles contract or shorten, your bone moves. Skeletal muscles are voluntary muscles (which means we can consciously control them)

Composition of skeletal muscle (p. 919)
Skeletal muscle is made of cells called muscle fibers Muscle fibers have many nuclei and are separated by bands called striations Muscle fibers are gathered in groups called fascicles Muscle fibers are made of the following: Myofibrils Myosin Actin

Composition of skeletal muscle (p. 920)
Myofibrils are threadlike structures that make up a muscle fiber They are made of 2 proteins that enable a muscle to contract Myosin: Thick protein fibers that mesh with actin proteins Actin: Thin protein fibers that overlap with myosin proteins Each actin-myosin bundle is bordered by an area called a Z line. This region from one Z line to the next is called a sarcomere

Contraction of muscle There is a “head” on myosin that fits into “grooves” created by actin When a muscle contracts the myosin “head” pulls the actin strand and shortens it The “head” can then move to another “groove” in the actin to continue to shorten the actin strand This process requires ATP If you work out hard, you don’t have enough oxygen to go through the Kreb’s cycle oxygen debt Your muscles begin to run out of ATP (muscle fatigue) You must go through lactic acid fermentation (this is why your muscles get sore lactic acid build up)

Contraction of muscle (p. 921)
Most muscle are arranged as opposite pairs Muscles always pull bones, not push them so you need to be able to contract in two different directions Flexor bends the joint to flex the limb (biceps pull your arm in) Extensor flexes to straighten the limb (triceps allow you to straighten your arm)

Connectors (p. 916) Ligaments-connect bone to bone
Tendons-connect muscle to bone Origin: where a muscle attaches to a stationary bone Insertions: a muscle attaches to a mobile bone

Smooth Muscle Smooth muscles are found in the hollow parts of the body. They are composed of interlacing sheets of muscle cells. Unlike skeletal muscle, they have a single nucleus. There are no striations in smooth muscle (no severe contractions) This would be in places like the lining or the stomach (moves food), intestines (moves waste), blood vessels (change the diameter) and the bladder (moves urine). A smooth muscle is an involuntary muscle (This means that you cannot consciously control this muscle-they just work when needed) They move things through the body with a wave-like motion (peristalsis)

Cardiac Muscle Cardiac muscle makes up the heart (along with blood vessels) that makes up the cardiovascular system Cardiac muscles contract automatically to squeeze the walls of the heart inward. They are similar to both skeletal and smooth muscle. They are striated (so they can contract) They have a single nuclei They are involuntary The heart beats nonstop about 100,000 times each day. Cardiac muscles don’t get tired-they work constantly until you die

Integumentary This system includes skin, hair, nails, and various glands The function of this system is protection-it is a barrier from injury and infection The glands are responsible for secreting sweat and oils to release waste or cool the body Subcutaneous layer

Epidermis (p. 925) Melanin is produced in the dermis
The epidermis is the outermost layer of skin It is composed of an outer (corneal layer) and a lower (basal) layer This outer layer is made mostly of dead skin cells filled with a protein called keratin This makes skin tough and leathery to resist the outer environment. It also acts as water-proofing Skin color for the epidermis is controlled by the amount of melanin (a brown pigment) Melanin is produced in the dermis

Dermis (p. 925) Inner layer of the skin composed of living cells and specialized structures Blood vessels Sensory neurons Hair follicles (hair is made of dead cells filled with keratin. Oil from glands keep them supple) Glands Sweat glands to cool the body Oil glands to soften skin, prevent water loss, etc Because the glands produce sweat, the dermis is responsible for temperature regulation

Subcutaneous layer A fatty layer beneath the dermis that acts as insulation and storage of energy (fat cells)

Circulatory The circulatory system is made up of the vessels and the muscles that help and control the flow of fluid around the body. It consists of the cardiovascular system and the lymphatic system As blood begins to circulate, it heads from the lungs to the heart

Circulatory Cardiovascular system Lymphatic system Lymph nodes Heart
Blood vessels Blood Lymphatic system Lymph nodes Lymph vessels Lymph

Heart The center of the cardiovascular system is the heart
A septum (wall) separates the heart into 2 sections Right side: pumps blood to the lungs (oxygen deficient blood) Left side: pumps blood from the heart to the rest of the body (oxygen rich blood)

Heart Each side of the heart is separated into an upper and lower chamber Each upper chamber is called an atrium You have a left atrium and right atrium (depends on what side of the septum you are) Each lower chamber is called a ventricle You have a left and right ventricle

Movement of blood To control the flow of blood, you have flaps ( called valves)that only open in one direction The valve that controls blood flow from the right atrium to the right ventricle is called the tricuspid valve The valve that controls blood flow from the left atrium to the left ventricle is called the mithral valve

Blood flow – Part 1 (p. 934) Deoxygenated blood enters the right atrium through a vessel called the vena cava Superior vena cava comes from above the heart Inferior vena cava comes from below the heart Right atrium sends the deoxygenated blood to the right ventricle Right ventricle contracts and sends the blood through the pulmonary arteries to the lungs

Blood flow – Part 2 (p. 934) The deoxygenated blood gains oxygen in the lungs (discussed in the respiratory system) Oxygenated blood returns to the left atrium through the pulmonary veins Oxygenated blood is pumped into the left ventricle Contraction of the left ventricle forces blood up through a large blood vessel called the aorta The blood is then transported to the rest of the body

Circulatory It leaves the heart from the left ventricle and goes into the aorta. The aorta is the largest artery in the body. The blood leaving the aorta is full of oxygen

Blood vessels There are 3 primary blood vessels in the circulatory system Arteries: largest of the muscular vessels that carry blood away from the heart Made of several arterioles Veins: vessels that contain several valves that bring blood to the heart Made of several venules Vericose veins are caused by poor valves Capillaries: very small blood vessel where gases (ie. oxygen) can diffuse to the body tissues surrounding the capillary.

Blood Vessels: Lumen = cavity

Circulatory The oxygen rich blood travels throughout the body through arteries Arteries are tough, elastic tubes that carry blood away from the heart. Arteries branch into capillaries(which are the smallest blood vessels with walls only one cells thick)

Circulatory Much of the gas/nutrient exchange between the blood and body cells occurs in the Capillaries, which eventually lead to veins Body cells get oxygen from the red blood cells, then give them carbon dioxide (a waste product) Veins carry the blood to the heart. Once the blood reaches the heart, it is pumped back into the lungs to expel the carbon dioxide and obtain oxygen

Diseases of the circulatory system
Hypertension: also known as “high blood pressure”. This places stress on the walls of arteries and run the risk that blood vessels will burst Stroke can be caused by a burst blood vessel in the brain Hypotension: also known as “low blood pressure”. Often feels cold because blood is not able to reach the extremities efficiently Atherosclerosis: when an artery is blocked by a build up of fatty material Increases blood pressure and can lead to a burst blood vessel

Lymphatic system (p.939) Part of the circulatory system, the lymphatic system is responsible for returning fluids (lymph) that have collected in the blood stream Important differences Lymphatic system is one way (not a circuit) There is no pump (like the heart) Skeletal muscles squeeze fluid through vessels similar to blood vessels Lymph passes through lymph nodes that act as filters to remove foreign particles, microorganisms or other tissue debris Lymph nodes have specialized cells called lymphocytes (specialized white blood cells that fight disease and infection)

Blood Blood is made of many different fluids and cell types
Plasma: yellowish fluid that contains about 90% water and many nutrients, wastes, chemical messengers, etc Red blood cells : (erythrocytes): oxygen binds to the hemoglobin molecule in red blood cells in the lungs. When they reach the cells in body tissues, they give up the oxygen to the cells and pick up carbon dioxide waste through another gas exchange. Hemoglobin: an iron containing protein on red blood cells

Blood White blood cells (leukocytes): cells of the immune system used to fight disease and infection Phagocyte: white blood cell that engulfs infectious cells (ie bacteria) and destroys them Antibodies: produced by another white blood cell that detects infections cells and activates the bodies immune system Antibodies detect different protein markers on red blood cells. These proteins give us our blood type (A, B, AB, O). If you don’t have an A or B on your red blood cell, your immune system will attack foreign blood with those “antigens”. Platelets: fragments of larger cells that can bind together at the site of tissue damage (this is what forms a scab)

Respiratory (p. 947) The respiratory system allows us to breathe
The diaphragm is a muscle contracts and relaxes to move air in and out of your lungs The lungs are the actual site of gas exchange.

Air Pathway (p. 947) Breathing begins at the nose and mouth
Small hairs in the nose, mucous, and a nasal cavity lined with cilia trap many particulates that are swept into the throat to be swallowed. The air moves to the pharynx, a tube at the back of the nasal cavity and mouth The epiglottis is a flap of cartilage that can close or open. This prevents food particles from going into the lungs

Respiratory The nasal cavity and throat filter, moisten and warm the air we breathe in Some of the epithelial tissue that line this system has cilia which trap particles that don’t belong and send them up for you to cough out Some of the cells produce mucous

Air Pathway (p. 947) The air continues down the pharynx to the trachea, a rigid pipe made of cartilage This is again lined with cilia to trap unwanted particles The trachea branches into 2 bronchi made of smooth muscle and cartilage These are also lined with cilia The bronchi then separate into several tubes in the lungs called bronchioles At the end of these bronchioles are several aveoli. This is what oxygen and carbon dioxide are exchange.

Respiratory (p. 947) The trachea joins the nasal passage and throat to the lungs. The bottom of the trachea splits into two branches called bronchi. One enters the right lung and one goes to the left lung. Aveoli are at the end of the bronchi.

Respiratory (p. 947) The bronchial tree's job is to spread the air from the trachea over a very wide area as quickly as possible. The air travels until it hits little bags called alveoli, where oxygen is absorbed into the blood stream through capillaries and CO2 is released.

Immune The immune system defends people against pathogens, or any invader in your body. Through a series of steps called the immune response, the immune system attacks organisms and substances that invade our systems and cause disease.

Immune Before you are infected by a disease, your body has a first line of defense The skin serves as a physical barrier to outside pathogens Mucous membranes secrete mucous which traps pathogens which can be expelled or destroyed by the acid in your stomach Digestive acids in your stomach

Immune Many of the symptoms you feel when you are sick are the result of your body fighting invaders: Lymph nodes swell when your sick because they are producing more white blood cells Your fever is meant to slow the growth and reproduction of pathogens (invaders) However a fever over 103°F can denature your proteins Mucous secretions and coughing expel pathogens

Immune If a pathogen gets through your first line of defense, you have another level of protection nonspecific immune response If your body is damaged (cut or other break in the skin), your body will start an inflammatory response Blood and lymph go to the area of injury Histamine is released to attract other cells of the immune system, allow more fluids to the area (causes swelling) and begins the blood clotting process with platelets White blood cells called phagocytes come in and destroy all pathogens and foreign material

Immune Your last line of defense against pathogens is the immune system (specific immunity) This is a specific response aimed at a specific infection This is not an immediate response (this is why there is a delay between begin exposed to the disease and showing symptoms) The immune cells of the immune system are called lymphocytes or leukocytes

Immune The cells that are part of this defense system are white blood cells, or leukocytes. Leukocytes are produced or stored in many locations throughout the body, including the thymus, spleen, lymph nodes and bone marrow.

Immune The immune system has it’s own transportation vessels which are a part of the circulatory system They are called the Lymphatic Vessels Lymph fluid can also travel in the blood vessels

Immune Cells B cells T cells Made and developed in the bone marrow
Produce antibodies that recognize antigens (any substance that the immune system believes is foreign to the body) T cells Made in the bone marrow and developed in the thymus Helper T cells recognize part of the antigen on the surface of macrophages They call in cytotoxic T cells Cytotoxic T cells destroy cells

CELL-MEDIATED IMMUNITY
Before an immune response can begin, it must be activated In a cell-mediated immune response, a macrophage (specialized white blood cell that ingests pathogens) will engulf a foreign substance and present an antigen on its surface Receptor proteins on T helper cells bind with the antigen and this causes the macrophage to release a substance called interleukin-1 (IL-1) IL-1 activates the T helper cell and the T helper cell releases a substance called interleukin-2 (IL-2)

CELL-MEDIATED IMMUNITY
IL-2 stimulates the production of more T helper cells and activates T cytotoxic cells The T cytotoxic cells kill all your cells that have the foreign antigen Cytotoxic cells destroy your infected cells and cancer cells A third type of cell, T suppressor cells are thought to be responsible for shutting down the cell-mediated immune response

HUMORAL IMMUNE RESPONSE –START HERE
The release of interleukin-2 (IL-2) from the cell- mediated response also activates B cells B cells begin to produce antibodies B cells that produce antibodies are called plasma cells Antibodies are proteins that specifically bind to the antigen Antibodies work by binding to foreign substances so that macrophages can come in and destroy them, or Inactivate foreign toxins or viruses

HUMORAL IMMUNE RESPONSE
The first time that your body responds to an infection/disease is called a primary immune response It takes your body about a week to build up enough of an immune response to fight it off (this is when you feel sick) If you are exposed to an infection/disease again, your body mounts a secondary immune response After a primary immune response, some of your plasma cells become memory cells that will recognize the foreign antigen Secondary immune response only takes a few hours (This is why they say you are immune to a disease. The response is so quick you don’t get sick)

VACCINATIONS How do vaccines work?
You are injecting just the plasma membrane/cell wall of a pathogen, or An attenuated pathogen (one that has been rendered inactive by heat, but still has the membrane proteins) Your body will create memory cells to those membrane proteins and you will be mounting a very rapid secondary immune response if exposed to the disease again.

PROBLEMS WITH THE IMMUNE SYSTEM
Allergies: a physical response to a common foreign antigen (pet dander, pollen, etc) Asthma: a foreign antigen causes the respiratory bronchioles to over-react and narrow (reduced airflow) Autoimmune disease: your immune cells recognize some part of your body as foreign. This causes your immune system to destroy part of your own body HIV: destroys the cell-mediated immunity of your body. HIV doesn’t kill you. It’s an infection you get after HIV has destroyed your defenses

Gastrointestinal tract
The gastrointestinal tract, or digestive tract, is responsible for ingesting and breaking down nutrients to be used by the body It starts at the mouth and ends with the anus The following is a breakdown of the digestive tract

Digestive System MOUTH ESOPHAGUS LIVER STOMACH GALL BLADDER PANCREAS
SMALL INTESTINE LARGE INTESTINE RECTUM APPENDIX ANUS

Digestive The food we eat must be broken down into chemicals that the body can use. This whole process is called digestion and that is the function of the digestive system.

Digestive The first step takes place in your mouth, where food is broken down into smaller pieces by the mechanical action of your teeth Your saliva also contains an enzyme, salivary amylase, that breaks down starch (a type of sugar) into simpler sugars

Digestive ESOPHAGUS After being swallowed, the food travels down your pharynx to your esophagus, which is about 10 inches long. Since both air and food travel down the pharynx, a flap of tissue called the epiglottis prevents food from going down the trachea The esophagus is covered in muscles that push the food to your stomach.

Digestive STOMACH The stomach releases acids and enzymes that break down the food The stomach has several layers of smooth muscle that aid in the mechanical digestion of food. The stomach also releases gastric fluids to aid in chemical digestion

Digestive After food enters the stomach from the esophagus, the cardiac sphincter closes to prevent food and gastric juices from entering the esophagus Food remains in the stomach for 3-4 hours The smooth muscles of the stomach churn the stomach to mix the food with the gastric juices and form chyme Pepsin is a digestive enzyme that works at low pH HCl is the acid released into the stomach to make sure the pepsin is active

Digestive When digestion is finish, the stomach forces the chyme into the small intestine through the action of peristalsis, wave- like muscle contractions that cause the substance to move Once in the small intestine, the pyloric sphincter closes to prevent the chyme from returning to the stomach

Digestive The small intestine is the final place for digestion
It is about twenty feet long and one inch in diameter. It is made of 3 parts: Duodenum Jejunum Ileum It releases more chemicals to break down food This is also where the nutrients from food are absorbed through small finger-like projections called villi SMALL INTESTINE

Digestive Waste products and food that are not absorbed in the small intestine pass into the large intestine (or colon) through perstalsis The large intestine is only 5 feet long, but is much wider than the small intestine LARGE INTESTINE

Digestive The large intestine removes water from the food waste to create feces A meal may take up to three days to pass through your digestive system. It spends about three hours in your stomach and up to 20 hours in your large intestine!

Digestive The pancreas is an elongated gland that is below the stomach. It has many functions: It releases hormones to control blood sugar (ENDOCRINE) It can release sodium bicarbonate to neutralize the stomach acid before chyme enters the small intestine (DIGESTIVE) Produces many enzymes that help to break down proteins, carbohydrates, lipids and nucleic acids (DIGESTIVE) PANCREAS

Digestive The Liver : Stores glucose as glycogen (DIGESTIVE)
Breaks down toxic substances, bacteria and old blood cells (EXCRETORY) Secretes bile which is necessary to digest lipids/fats (DIGESTIVE) The extra bile from the liver is stored in the Gall Bladder (DIGESTIVE) GALL BLADDER

Excretory system We’ve already discussed how waste is removed form the gastrointestinal tract through the large intestine and anus The other major way to remove waste is through the urinary system Kidneys Ureter Urinary bladder Urethra

Kidneys Responsible for removing most of the nitrogenous wastes
Most nitrogenous waste first goes to the liver in the form of ammonia Ammonia is extremely toxic so the liver converts into the less toxic chemical urea Urea is sent into the blood stream where it enters the kidneys for disposal

Excretory – SEE p. 994 The kidney is made of several units called nephrons Nephrons are tiny tubes that end in a tight ball of capillaries called Bowman’s capsule The purpose of the nephrons is to filter the blood Blood first enters Bowman’s capsule where nutrients in the blood are reabsorbed while the waste is allowed to pass The blood continues to flow through the nephron and continues to filter out nutrients and allow the waste to pass

Excretory The nutrients reabsorbed during the filtration process are returned to the body The fluid and waste that remain form urine and are transported to the ureter, a narrow collecting tube attached to the kidney Each ureter leads to a storage organ called the urinary bladder When the waste is ready to be evacuated, muscular contractions force the urine out through a tube called the urethra

Other avenues of excretion
In addition to excretion through the gastrointestinal tract and urinary system, we have already discussed other avenues of waste removal: Lungs: removes CO2 Skin: removes wastes, salts and oils in the subcutaneous layer

Nervous The nervous system is divided into two main systems:
The central nervous system (CNS) The peripheral nervous system

Central Nervous System
The spinal cord and the brain make up the CNS. Its main job is to get the information from the body and send out instructions.

Central Nervous System
The brain helps to control all of the body systems and organs, keeping them working like they should. The brain communicates with the rest of the body through the spinal cord and the nerves. This system also gives instructions to all parts of the body about what to do and when to do it Reflexes are involuntary, self protective movements and are not controlled by your brain (they just go to spinal cord and back)

Anatomy of the brain The brain is composed of 4 basic parts
Cerebrum: The cerebrum is responsible for higher levels of thinking and communication Speech, reasoning Diencephalon: This is the relay center for the brain where information entering or leaving the brain is routed Brain stem: This is responsible for a lot of involuntary responses in the body Heart rate, homeostasis, respiration, sensory input Cerebellum: Helps to coordinate movement

Spinal cord The spinal cord is the central relay between the brain and the rest of the body A flexible spine gives protection to the nervous tissue that makes up the spinal cord Signals are both sent are received via the spinal cord

Peripheral Nervous System
The peripheral nervous system is made up of all of the nerves and the wiring. This system SENDS the messages from the brain to the rest of the body as electrical signals.

Peripheral Nervous System
Cells of the nervous system are called neurons Neurons carry messages in the form of an electrical impulses. The messages move from one neuron to another to keep the body functioning. Unlike other body tissues, nerve cells cannot also be repaired if damaged due to injury or disease.

Structure of neuron The cell body contains the organelles and nucleus of the cell Dendrites are structures that receive signals from other neurons Axons are used to transmit signals away from nerve

Structure of neuron The axon of the neuron is covered in a lipid layer known as the myelin sheath The myelin sheath acts as an insulator like a rubber cord Schwann cells surround the axon and are responsible for making the myelin sheath Gaps in the myelin sheath are known as nodes of Ranvier Axons end in an axon terminal with a gap between the next neuron known as a synapse

How do neurons work? Nerves send signals in the form of an action potential All neurons contain an electrical charge inside the cell that is different than outside. This difference in charge is called a membrane potential When the charge is changed (by allowing ions into or out of the membrane), you can move a charge along the nerve Change the potential in different spots

How do neurons work? Resting potential
When the neuron is not sending or receiving a signal, there are more negatively charged proteins and potassium ions, K+, inside the cell and more sodium ions, Na+ outside the cell net negative charge Action potential When a signal is sent along the neuron, ion channels allow the sodium ions into the cell (via a concentration gradient) through a sodium channel (facilitated diffusion) net positive charge This changes the charge of the cell and the signal causes the next cell in line to start an action potential

How do neurons work? After the action potential, the cell needs to regain its state of resting potential To do this it utilizes the sodium- potassium pump to pump the sodium out of the cell Active transport using ATP During this time, the nerve cannot send another signal and is called the refractory period

Sending a signal between neurons
A neuron can only send a signal to another neuron through the synapse To do this, a neurotransmitter called acetylcholine is released from the axon terminal Acetylcholine travels across the neuron and stimulates the next neuron, muscle or organ that needs to receive the signal After the acetylcholine has sent the signal, an enzyme called acetylcholine esterase breaks down the acetylcholine

Acetylcholine

Somatic vs. Autonomic Nervous System (Peripheral Nervous System)
Called the voluntary nervous system Motor neurons are the ones that activate different muscles and glands Allows for conscious control of your muscles and lets you control your movement There is also an involuntary component involved in reflexes Autonomic Called the involuntary nervous system Sympathetic: called the fight or flight response (increased heart rate, pupils dilate, etc) Parasympathetic: resting response (decrease heart rate, pupils constrict, etc)

Sensory Organs There are many different sensory receptors depending on what they detect Mechanoreceptor: responds to movement, pressure and tension Photoreceptor: responds to light Chemoreceptor: responds to chemicals Thermoreceptor: responds to temperature change Pain receptor: responds to tissue damage

Hearing and balance (Diagram on p.1017)
The outer ear is responsible for “capturing” sound and transmitting it down the auditory canal The auditory canal leads to the tympanic membrane or eardrum Sound vibrations (moving air) cause the tympanic membrane to vibrate and move three small bones: the hammer, the anvil and the stirrup

Hearing and balance After the three bones are set in motion, the stirrup transfers vibrations to a membrane called the oval window The oval window leads into the cochlea The cochlea has 3 fluid filled chambers that are separated by membranes Vibrations from the oval window cause hair cells within the fluid of the cochlea to move This movement is interpreted and sent by your auditory nerve to your brain as sounds

Hearing and balance In addition to hearing, the ears are responsible for maintaining balance In the middle ear there is a tube connecting to the throat, Eustachian tube This allows air pressure to equalize on both sides of the tympanic membrane (popping your ears) Additionally, in the inner ear, there are 3 fluid filled chambers called the semicircular canals Each canal is situated in one of 3 axis There are mechanoreceptors in the semicircular canals that can be interpreted as relative position

Vision: (Diagram on p. 1019) All sight is based on light striking a place in the back of the eye called the retina Light first passes through the cornea, a protective outer layer of the eye Next, light passes through the pupil, or the opening in the eye that controls the amount of light It contracts when very bright It dilates when dim or when “fight or flight” is active The muscles that control the pupil are located in the pigmented iris

Vision The light that passes through the iris hits the lens
This is a crystalline structure that allows the light to be refracted, bent, to produce a clear image If your lens cannot be properly “bent”, you will need some sort of vision correction (glasses, contacts) Again, the muscles in the iris controls the amount of light passing into the eye Within the retina are specialized photorecptors called rods and cones Rods respond to dim light Cones respond to bright light The signals that hit the rods and cones are sent by the optic nerve to be interpreted by the brain

Taste and smell Most people perceive taste because of chemoreceptors located on the tongue, or taste buds Taste buds are located between the bumps on your tongue, papillae You have chemoreceptors for: sweet, salty, sour and bitter The signals are sent to the brain to interpret taste.

Taste and smell Smell works very similar to taste
Instead of chemoreceptors on your tongue, smell has specialized chemoreceptors in your nasal passages called olfactory receptors When a chemical binds to an olfactory receptor, the information is sent to your brain and interpreted as smell

Touch You have many mechanoreceptors throughout the skin
They are concentrated in the face, tongue and fingertips You have two types of thermoreceptors in the skin Sensitive below 20°C (cold receptor) Sensitive between 30°C and 45°C (heat receptor) You have many types of “pain” receptors located throughout the skin All receptors travel to the spinal chord and up to the brain

Endocrine system

Endocrine system System that produce hormones to regulate body activities Hormones are produced by various endocrine and exocrine glands throughout the body Endocrine glands: ductless gland that secrete hormones into the blood stream or fluids of nearby tissues Exocrine glands: gland with a tube-like structure that transport substances to specific locations inside or outside the body

Hormones Hormones are chemicals that influence body activity. They are transported throughout the body using the blood stream and extracellular fluid Amino-acid based hormone: water soluble hormone Binds to protein receptors on the cell membrane Often the first to trigger a signal in the cell Steroid hormone: lipid soluble hormone Lipid soluble allows the hormone to enter through the plasma membrane Causes the cell to activate existing enzymes or to initiate protein synthesis for specific enzymes

Organs of the endocrine system
Hypothalamus Pituitary Thyroid Adrenal Gonads Pancreas Thymus Pineal Parathyroid Digestive cells

Hypothalamus/Pituitary: List of hormones released (p. 1035)
Hypothalamus: “controls” much of the endocrine system Located in the part of the brain that initiates many of the responses of the endocrine and nervous system The hypothalamus often starts the hormone response by sending signals to the pituitary gland Releasing hormones: stimulates the pituitary gland to release hormones (ON SWITCH) Release-inhibiting hormones: inhibit the release or production of hormones (OFF SWITCH)

Thyroid Thyroid gland: located near the lower part of the larynx
Thyroid hormones help to maintain normal heart rate, blood pressure and body temperature Also helps to transport calcium from the blood to the bone to generate bone tissue for healthy bone development and repair Hyperthyroidism: produce to much thyroid hormone Symptoms include: hyperactivity, weight loss, high blood pressure, increased heart rate Hypothyroidism: do not produce enough thyroid hormone Symptoms include: lethargy, lack of growth, weight gain, low heart rate, low body temp

Adrenals Adrenal glands: one adrenal is located above each of the kidneys Produces epinephrine and norepinephrine (also known as adrenaline and noradrenaline) Initiates fight or flight respons – increased heart rate and blood pressure, increase blood sugar levels, increase oxygen flow to lungs Also produces cortisol which promotes the cells to produce glucose from proteins This hormone is often released when the individual is stressed

Gonads Gonads begin producing hormones when the individual hits puberty Responsible for the development of secondary sex characteristics Responsible for the maintaining the production or release of the sex cells

Pancreas The pancreas is important because of its production of insulin Insulin is responsible for regulating the levels of glucose available in the blood and available to cells Diabetes mellitus is a condition where cells are unable to receive blood glucose so there is a high level of glucose in the blood Type 1: The immune system attacks the cells that produce insulin (usually treated with a daily insulin injection) Type II: A hereditary condition that is usually triggered by obesity and inactivity (may be treated with diet and exercise)

Thymus / Pineal / Parathyroid / Digestive cells
Thymus: produces that hormones that stimulates the maturation of T-cells Pineal: releases melatonin which helps to regulate sleep patterns Parathyroid: causes calcium to be transferred from the bone to the blood (opposite of thyroid and must in unison) Digestive cells: helps to release various fluids during digestion (stomach acid, digestive enzymes, gastric juices)

Homeostasis: How it works
The ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes In animals such as ourselves, the internal environment of our bodies must have certain conditions within tolerable limits to continue to function properly Environmental conditions that cause reactions are called stimuli (plural = stimulus) A feedback mechanism occurs when the level of one substance influences the level of another substance or activity of another organ.

Negative Feedback Negative feedback is where various receptors and effectors bring about a reaction to ensure that conditions remain favorable In negative feedback, a final step in a reaction inhibits the start of another reaction A receptor is a structure that monitors internal conditions, sense changes, and initiate a response (usually by sending signals to the brain) Effectors are muscles, organs, or other structures that receive signals from the brain. When an effector receives a signal from the brain, it changes its function in order to correct the change from normal conditions.

Positive Feedback Positive feedback mechanisms are designed to accelerate or enhance the output created by a stimulus that has already been activated Push levels/conditions in the body out of normal ranges When the body senses a change, it increases or accelerates that change Happens much less often than negative feedback

Homeostasis Depending on the physiological conditions, a hormone can act as a positive or a negative feedback For example if you release an initial hormone and it causes subsequent hormones to be released, this is positive feedback Adrenocorticotropic hormone (ACTH): stimulates the production of cortisol in the adrenals When a hormone inhibits the release of a hormone, this is negative feedback Release-inhibiting hormones produces by the hypothalamus prevents the production of hormones in the pituitary

Human Anatomy.

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Human Anatomy.

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