Human Anatomy and Body Systems Levels of Organization

Human Anatomy and Body Systems

Levels of Organization Remember, the human body is organized in several levels, from the simplest to the most complex. . . Cells – the basic unit of life Tissues – clusters of cells performing a similar function Organs – made of tissues that perform one specific function Organ Systems – groups of organs that perform a specific purpose in the human body The purpose of the 10 organ systems is for the human body to maintain homeostasis

The 10 Human Body Systems 1) nervous system 2) respiratory system 3) excretory system 4) muscular system 5) endocrine system 6) immune system 7) digestive system 8) skeletal system 9) circulatory system 10) reproductive system

The Digestive System Purpose: to convert food particles into simpler molecules that can be absorbed into the bloodstream and used by the body 2 kinds of digestion: 1) mechanical – physically breaking down food 2) chemical – using ENZYMES to chemically hydrolyze food

• Major Organs and their Functions: • Mouth: 1) mechanical - chew and grind up food 2) chemical - saliva (from salivary glands) has amylase enzyme (ptyalin) that breaks down starch ---- sugar. • Esophagus – tube that connects mouth to stomach. • Peristalsis (wavelike muscular contractions that move food) begins here. Produces mucus. Food passes thru cardiac sphincter.

Stomach – has gastric glands 1) mechanical – muscular organ – churns food 2) chemical - secretes an strong acid (HCl) that is necessary for enzyme PEPSIN to work. Pepsin starts protein digestion. Once the food is broken down in the stomach and mixed with digestive juices, it becomes a liquid called chyme. Chyme passes into SI through pyloric sphinctor.

• Small Intestine – the chyme enters the small intestine where: • 1) digestion is completed w/ the help of intestinal ENZYMES (amylases, proteases & lipases) and secretions from accessory organs (pancreas & liver). • 2) absorption - end products of digestion (simple sugars, amino acids, etc. ) are absorbed into the bloodstream through folded surfaces called villi (increase the surface area). • Large Intestine – reabsorbs of water from the chyme back into the bloodstream and gets the waste ready for excretion (forms feces) with help of bacteria.

Accessory Organs: Pancreas – produces: a) digestive enzymes (amylases, proteases & lipases) that are sent to small intestine b) Produces the hormone insulin that regulates blood sugar levels c) Diabetes can be a result of the pancreas not making enough of these enzymes. Liver – produces bile, which EMULSIFIES (physically breaks down) fats in foods

• Gallbladder – pouch-like organ that stores bile temporarily • 3 processes: • Ingestion – taking in of food • Digestion – break down of food • Egestion – removal of undigested, nonusable food material

Image of the Digestive System

The Excretory System Purpose: to rid the body of cellular wastes, including excess water, salts and urea (nitrogenous waste resulting from breakdown of proteins/amino acids) Major Organs and Their Functions Kidneys – the main organs of the excretory system blood enters the kidney and the kidney filters out urea, excess water and other waste products eventually travel out of the kidney as urine. Kidneys are made up of millions of nephrons (mini filters)

• • • Functional unit of kidney – nephron; carries out 2 processes: Filtration – all dissolved substances (harmful & harmless) are filtered out of blood. BOWMANS CAPSULE Reabsorption – harmless (useful) materials are put back into blood. LOOP OF HENLE

Skin – sweat glands remove excess water and salts from the body. Sweat actually cools body down & maintains homeostasis Lungs – expel the waste gas carbon dioxide upon exhalation Image of the Excretory System Carry urine into bladder Temorarily stores urine Releases urine from body

The Respiratory System Purpose: to provide the body with a fresh supply of oxygen for cellular respiration and remove the waste product carbon dioxide Major Organs and Their Functions Nose – entry and exit point for air; ciliated & produces mucus Pharynx – serves as a passage way for both air and food at the back of the throat

• Larynx – your “voicebox”, as air passes over your vocal chords, vibrations cause sound • Trachea – the “windpipe”, or what connects your pharynx to your lungs; supported by rings of cartilage • -- a piece of skin, called the epiglottis, covers the trachea when you swallow, preventing food from entering

Bronchi – two passageways that lead from the trachea to your lungs (one for each lung) -- the bronchi are further subdivided into bronchioles -- eventually, the further subdivisions lead to tiny air sacs called alveoli (RESPIRATORY SURFACE) -- alveoli are in clusters, like grapes -- capillaries surrounding each alveolus is where the exchange of gases with the blood occurs

• The diaphragm is the muscle that causes you to breath • Moves down to bring about inhalation • Moves up to bring about exhalation • -- hiccups are involuntary contractions of the diaphragm

Image of the Respiratory System

The Circulatory System Purpose: to deliver oxygenated blood to the various cells and organ systems in your body so they can undergo cellular respiration Major Organs and Their Functions Heart – the major muscle of the circulatory system -- pumps blood through its four chambers (two ventricles and two atria) -- pumps deoxygenated blood into the lungs, where it gets oxygenated, returned to the heart, and then pumped out through the aorta to the rest of the body -- valves regulate the flow of blood between the chambers

Pathway of Blood Through the Heart

Arteries – carry oxygenated blood away from the heart and to the major organs of the body. PULSE is felt in arteries ONLY! Veins – carry deoxygenated blood back to the heart away from the major organs of the body. Veins have valves! Capillaries – thin-walled blood vessels; gas exchange occurs through these walls (oxygen & carbon dioxide are exchanged)

• Blood – the liquid tissue that flow through the circulatory system. 4 components: 1. red blood cells - contain hemoglobin, an iron-containing pigment that carries oxygen. Most numerous blood cells. 2. white blood cells - function in the immune system. Numerous kinds: phagocytes (macrophages) lymphocyte, B cells/ T cells 3. Platelets – initiate the blood clotting process 4. Plasma – clear, yellowish liquid portion – carries nutrients & wastes

Comparison of Blood Vessels

Blood Components

Image of the Circulatory System

AIDS • Acquired immune deficiency disorder • Caused by an RNA (retro) virus • The virus attacks the t helper cells that are necessary for the body to defend itself • Spread by bodily fluids (blood & reproductive secretions) • Death usually results from infection due to weakened immune system • Associated with risky behaviors , such as IV drug use & unprotected sex

The Nervous System Purpose: to coordinate the body’s response to changes in its internal and external environment. Major Organs and Their Functions Brain – control center of the body, where all processes are relayed through & information is interpreted 3 parts: 1) cerebrum - controls thought, senses, learning 2)cerebellum - coordinates motor functions, balance 3) medulla – controls involuntary functions (breathing, heartbeat, digestion, reflexes such as blinking & sneezing

• Spinal Cord – sends instructions from the brain to the rest of the body and vice versa • Nerves – conduct impulses between brain and muscles and/or gland & sense organs (sensory & motor)

Major Parts of the Brain

Diagram of a Nerve Cell (Neuron) Motor Neuron – carries impulses from brain to muscles Sensory Neuron carries impulses from sense organs to brain

Reflexes • Reflexes are involuntary, quick responses to stimulus that are controlled by the spinal cord (of evolutionary significance).

The Endocrine System Purpose: to control growth, development, metabolism and reproduction through the production and secretion of hormones (chemical messengers – travel in bloodstream) Major Organs Location -- hypothalamus brain -- pituitary gland brain -- thyroid on trachea (throat) -- parathyroid on thyroid -- adrenal glands on top of kidney -- pancreas next to stomach -- testes outside lower ab -- ovaries inside lower ab

Endocrine Glands Hormones Hypothalamus Releasing factors Pituitary Gland Thyroid Growth hormone, ACTH, FSH, TSH thyroxine Parathyroid parathormone Adrenal Glands Adrenaline, steroid hormones (cortisol) Insulin & glucagon Pancreas (Islets of Langerhans) Gonads (testes/ovaries) testosterone (M) estrogen & progesterone(F)

How endocrine glands work • Endocrine gland produce hormones which are carried by the bloodstream to a target tissue where it has an affect:

Feedback (know for regent’s) • Mechanism by which hormone levels in the body are regulated.

The Skeletal System Purpose: to provide structure and support to the body, point of attachment for muscles, protects organs, stores minerals & produce blood cells Bones are where new blood cells are generated (in the marrow), and require the mineral calcium for strength

• • Major Bones of the Human Body -- femur (thigh bone) -- humerus (upper arm) -- radius and ulna (lower arm) -- cranium (skull) -- sternum (breastbone) -- clavicle (shoulder blade) • -- fibula and tibia (calf) -- vertebrae (back) • -- scapula (shoulder) -- pelvic bone • -- coccyx (tail bone) -- phalanges (fingers/toes)

The Muscular System Purpose: works with the skeletal and nervous system to produce movement, also helps to circulate blood through the human body -- muscle cells are fibrous and slide on top of each other Name 3 types of muscles Voluntary or Location Skeletal Involuntary Appearanc e Attached to bones Voluntary striated Smooth or visceral Organs, in blood vessels Involuntary smooth Cardiac Heart Involuntary striated

3 lines of Defense 1. Skin – also called the integumentary system, the skin is the body’s first line of defense; preventing entry of pathogens into the body. 2. Phagocytes are the white blood cell type that actually eats and destroys these antigens (pathogens) 3. White Blood Cells – recognize pathogenic agents (antigens) and create antibodies to tag and remove these antigens

The Immune System Purpose: to prevent the entry & spread of pathogens in the human body – MAINTAINS HOMEOSTASIS Vocabulary: 1. Pathogen – any organism that can cause sickness and/or disease (usually bacteria or virus) 2. Antigen – any foreign protein that brings about an immune response Antibody – a protein produced by an organism in response to a foreign antigen (to destroy it). Immune response – production of antibodies in response to foreign antigens

• Endocytosis is a process where cells absorb material (molecules such as proteins) from the outside by engulfing it with their cell membrane • Phagocytosis (literally, cell-eating) is the process by which cells ingest large objects, such as bacteria, or viruses. • Pinocytosis (literally, cell-drinking). This process is concerned with the uptake of solutes and proteins

Lymphatic System • Lymph Vessels – help restore fluid lost by the blood and return it to the circulatory system • Lymph Nodes – filter bacteria or cancer cells from lymph fluid