Human Nervous System-Anaphy Finals Review

**HUMAN NERVOUS SYSTEM** A complex network of neurons specialized to carry messages **TWO PARTS OF THE NERVOUS SYSTEM** **1. Central Nervous System** ▪ Central processing unit of the body ▪ Consists of the brain and the spinal cord ***[Brain]-***(For discovering new things, remembering, unde...

**HUMAN NERVOUS SYSTEM** A complex network of neurons specialized to carry messages **TWO PARTS OF THE NERVOUS SYSTEM** **1. Central Nervous System** ▪ Central processing unit of the body ▪ Consists of the brain and the spinal cord ***[Brain]-***(For discovering new things, remembering, understanding, making decisions, etc) o One of the important, largest, and central organ of the Human Nervous System o Control unit of the NS o Helps us in discovering new things, remembering, understanding, making decisions, etc. o Enclosed within the skull -- frontal, lateral, and dorsal protection. ***[Three major parts of the CNS]*** ***1) [Forebrain]*** \~ Anterior part of the brain \~ Consists of Cerebrum, Hypothalamus, and Thalamus. ***❖ Cerebrum*** Largest part of the brain *** Two hemispheres of Cerebrum*** [o Right Hemisphere] -- controls creativity, spatial ability, artistic, and musical skills [o Left hemispheres] -- speech, comprehension, arithmetic, and writing *** Five lobes*** [o Frontal] (front of the head) ✓ Handles things like attention, behavior control (what's appropriate or not), the ability to speak, and some types of muscle movements [o Parietal] (top of the head) ✓ Handles touch, temperature, and pain signals ✓ Perceive things around you ✓ Processing of sound, languages you speak, abilities to use numbers and count, and organize information and make decisions [o Temporal] (side of the head) ✓ Understand language when other people are speaking ✓ Recognizing people and objects ✓ Connect emotions with memories [o Insular] (deep inside the brain -- underneath frontal, parietal, and temporal lobes) ✓ Handles taste senses ✓ Helps process types of emotions like compassion and empathy [o Occipital] (back of the head) ✓ Manages eye's sensory input -- see movement and colors ***❖ Hypothalamus*** Acts as our body's smart control coordinating center Keeps our body in a stable state -- homeostasis Manages hormones -- body tempt., heart rate, hunger, mood, sex drive, sleep, thirst, etc. ***❖ Thalamus*** Body's information relay station -- all senses except small Gray matter structure of the diencephalon -- essential roles in human physiology Serves a unique role -- relaying sensory and motor signals, and also the regulation of consciousness, memory, learning, and alertness ***2[) Midbrain]*** \~ Smaller and central part of the brainstem ❖ Connects cerebrum to the spinal cord and cerebellum ❖ Sends messages to the rest of the body -- regulate balance, breathing, heart rate, etc. \~ Consist of *[Tectum]* and *[tegmentum]* ❖ Tectum: auditory and visual processing ❖ Tegmentum: coordination of movement, pain processing, alertness ***[3) Hindbrain]*** \~ Central region of the brain \~ Composed of Cerebellum, Medulla, and Pons ***❖ Cerebellum*** Back of the head -- between the cerebrum and brain stem Controls balance (walking and standing), responsible for muscle control, and for language processing and memory ***❖ Medulla Oblongata*** Manages heart, circulation, and breathing ***❖ Pons*** Provides route signals to travel and from your brain Spinal Cord o A cylindrical bundle of nerve fibers o Tissues are enclosed within the spine that connects all the parts of the body to the brain o From medulla and extends downwards o Enclosed in a bony cage called vertebral column -- surrounded by membranes called meninges o Concerned with spinal reflex actions and the conduction of nerve impulses to and from the brain **2. Peripheral Nervous System** ▪ Lateral part of the NS that develops from CNS -- connects different parts of the body with the CNS ▪ Carry out both voluntary and involuntary actions -- with the help of peripheral nerves ***Two types of Nerve Fibers*** 1\) Afferent Nerve Fibers \~ Responsible for transmitting messages from tissues and organs to the CNS 2\) Efferent Nerve Fibers \~ Responsible for conveying messages from CNS to the corresponding peripheral organ **[Classification of PNS]** 1\) Somatic Neural System (SNS) \~ Neural system that controls the voluntary actions in the body by transmitting impulses from CNS to skeletal muscle cells \~ Consists of somatic cells 2\) Autonomic Neural System (ANS) \~ Involved in involuntary actions like regulation of physiological functions (digestion, respiration, salivation, etc.) \~ A self-regulating system -- conveys impulses from the CNS to the smooth muscles and involuntary organs (heart, bladder, pupil) **Divided into two:** a\. Sympathetic Nervous System b\. Parasympathetic Nervous System PARTS OF THE NERVOUS CELL \*Activity regarding the parts of the nerve cell **Neuron** ▪ A structured functional unit of the nervous system ▪ Irregular in shape ▪ It can conduct electrochemical signals ***Parts of the Neuron*** o Dendrites \~ Stretches out from the cell body of a neuron \~ The shortest fibre in the cell body \~ Function: o Axon \~ Longest thread on the cell body of a neuron \~ Has an insulating and protective myelin sheath around it \~ Function: o Cell body \~ Consists of cytoplasm and nucleus \~ Function: o Synapse \~ Microscopic gap between a pair of adjacent neurons over which nerve impulses pass when moving from one neuron to the other \~ Function: ***Nerves*** ▪ Thread-like structures that emerge from the brain and spinal cord ▪ Responsible for carrying messages to all parts of the body ***[Three types of Nerves]*** o Sensory \~ Send messages from all the senses to the brain o Motor \~ Carry massages from the brain to all the muscles o Mixed \~ Carry both sensory and motor nerves **ENDOCRINE SYSTEM** **Endocrinology Has Been Practiced Over 2,000 Years** **-**Chinese healers in 200 B.C. used the compound saponin from seeds and the mineral gypsum to extract pituitary and sex hormones from human urine to make medicine The ***endocrine system*** is a network of glands and organs located throughout the body. From conception through adulthood and into old age, it regulates all biological processes in the body. **5 MAJOR ORGANS OF THE ENDOCRINE SYSTEM** **Pancreas** ***[Location:]*** -Back of the abdomen or belly ***[Characteristics and Function: ]*** Large, and tadpole-shaped. Main link between endocrine system and nervous system ***[Hormones:]*** 1.***Insulin -*** Lowers blood sugar levels 2.***Glucagon***: Raises blood sugar levels 3.***Somatostatin*** - Inhibits the release of several other hormones to maintain balance in the body 4\. ***Pancreatic Polypeptide*** - Regulates the digestive processes and appetite ***[Ovaries]*** **Hormones:** **1.Estrogen - "**Female sex hormone" **2. Progesterone** "Pregnancy hormone" ***[Testicle]*** Location: Underneath penis in the scrotum Characteristics and Functions: Small and round Releases sperm and sex hormones ***[Thymus]*** **Location:** At the upper chest behind the breastbone (sternum); just in front of and above the heart **Characteristics and Functions** It is pinkish-gray Made up of two irregularly shaped parts (lobes) The lobes have lots of small bumps called lobules on the surface Releases hormones that control the functions of the body Produced Hormones: **1.Thymopoietin** - Stimulates the production of T-Cells **2. Thymosin and thymulin -** Help develop specialized types of T-cells **3.Thymic humoral factor (THF)** - Supports T-Cell function to help the immune system work properly **6 MAJOR GLANDS OF THE ENDOCRINE SYSTEM** ***[Pineal Gland]*** Location: Brain Function: Produces melatonin (regulates sleep) ***[Pituitary Gland]*** **Location**: Brain **Function:** Releases 8 hormones, controlling other endocrine glands. Thyroid Gland Location: Neck Function: Regulates metabolism ***[Parathyroid Gland]*** **Location:** Behind thyroid gland **Function:** Regulate calcium levels (parathyroid hormone) ***[Adrenal Gland]*** **Location:** Top of kidneys **Function:** Manage metabolism, blood pressure, stress response. ***[Hypothalamus]*** **Location:** Sits beneath the thalamus, above the brainstem **Function:** Regulates body temperature, hunger, and thirst ***[Endocrine glands ]*** Produce and release hormones directly into the bloodstream. ***[Hormones]*** Regulate various bodily functions. ***[Balance]*** Of hormones is crucial foroverall health **FUN FACT** There are two types of Glands: ***[Exocrine and Endocrine Glands]*** However, the exocrine glands are different or are not part of the Endocrine System. These glands secrete substances that help your organs function, including sweat, breast milk, mucus and oil. -Your exocrine system is different from your endocrine system in that it secretes these substances through ducts. **A FEW PROCESSES NEED TO BE OPERATING CORRECTLY IN ORDER FOR THINGS TO CONTINUE:** ***1.*** The right amount*s* of hormones must be released by endocrine glands. ***2***. For the Hormones to be transported throughout the body, a robust blood supply is necessary. ***3.*** For the Hormones To bind and perform their function, there must be an adequate number of receptors **ENDOCRINE DISORDERS AND DISEASES** -In general, the endocrine system is essential to life, although you can survive without some of the glands as long as you take medications to replace the hormones you\'re lacking. - **Hypothyroidism** Too little hormones - **Hyperthyroidism** **-**Endocrine diseases that results when a gland produces too much hormones - **Gigantism(acromegaly)** - **Graves's disease** - **Heavy period** - **Polycystic ovary** - **Cushing syndrome** - **Pseudohypopara thyroidism** - **Dwarfism** - **Addison's disease** - **Diabetes** - **Osteoporosis** - **Mood disorder** - **Hypopitiutarism** - **Down syndrome** **FUN FACT:** ***Hormones Weren\'t Discovered Until the 20th Century*** -In the 1800s, scientists knew that some form of chemical messaging occurred between organs. Finally, in 1902, English physiologists Ernest Starling and William Bayliss coined the word \"hormones\" to describe pancreatic secretions. -In short, the body uses the endocrine system as its internal message network to control a number of physiological functions necessary for everyday life. **THE HEART** **Role of the heart** - The heart is a pump and its role is to pump blood around the body - It is actually two pumps in one - The heart's **right-side** pumping to the **lungs** and back to the **left-side** of the heart through vessels of the **pulmonary circulation.** - The **left side** pumps oxygenated blood to the **body tissues** and back to the **right side** of the heart through vessels of **systemic circulation.** **CARDIOVASCULAR SYSTEM** - The heart is a member organ of the cardiovascular system, which consist of the **heart, blood vessels, and blood.** - The heart of a healthy adult, at rest pumps approximately **5 liters** of blood per minute. - For the most people, the heart continues to pump at approximately that rate more than **75 years.** **Cardiovascular System** **THE DOUBLE CIRCULATORY SYSTEM**  **FUNCTIONS OF THE HEART** **1. Generates blood pressure** **2.Routes** **3.Ensures one way blood flow** **4. Regulates blood supply** **HEART CHARACTERISTICS** **Size:** It is a size of a fist and weighs less than 1LB **Location:** Between lungs in thoracic cavity **Orientation:** Apex (bottom) towards left side **PERICARDIA** **Pericardium:** - Double layered sac that anchors and protects heart **Parietal Pericardium** - Membrane around the heart's cavity **Visceral Pericardium** - Membrane on heart's surface **Pericardial Cavity** - Space around heart **HEART'S EXTERNAL ANATOMY** - A **coronary sulcus** extends around the heart, **separating** the **atria** from the **ventricles.** - The grooves, or **sulci,** which indicate the division between the **right and left ventricles,** extend inferiorly from the coronary sulcus. - The **anterior interventricular sulcus** extends inferiorly from the coronary sulcus on the anterior surface of the heart. - The **posterior interventricular sulcus** extends inferiorly from the coronary sulcus on the posterior surface of the heart. - The **superior vena cava and inferior vena cava** carry blood from the body to the right atrium, and **four pulmonary veins** carry blood from the lungs to the left atrium. - The **pulmonary arteries,** often called the **great vessels,** or the **great arteries,** carry blood **away** from the ventricles of the heart. - The **pulmonary trunk,** arising from the right ventricle splits into the right and left pulmonary arteries, which carry blood to the lungs. - The **aorta** arising from the left ventricle, carries the blood to the rest of the body. **HEART CHAMBERS (4 CHAMBERS)** **1. Left Atrium** **2. Right Atrium** **3. Left Ventricle** **4. Right Ventricle** **The Atria** - Superior chambers - Holding chambers - Small and thin walled - Contract minimally to push blood into the ventricles - Internal Septum, separates right and left atria **Ventricles** - Inferior chambers - Pumping chambers - Thing, strong walled - Contract forcefully propel blood out of the heart - Interventricular septum, separates right and left ventricles **Atrioventricular Heart Valves** - Valves between the atria and ventricles - Tricuspid Valve -AV valve between RA and RV -3 cusps - Bicuspid Valve (Mitral) -AV valve between LA and LV -2 cusps **Valvular Control** - Each ventricle contains cone shaped, muscular pillars called papillary muscles - These muscles are attached by strong, connective tissue strings called **chordae tendineae** to free margins of the cusps of the atrioventricular valves. - When the **ventricles** contract, the **papillary muscles** contract and prevent the valves from opening into the atria by pulling on the **chordae tendineae** attached to the **valve cusps.** **Semilunar Heart** - The **semilunar valves** have the **three-half moon shaped cusps,** and are valves between the **pulmonary trunk** and **aorta.** - **Pulmunary semilunar valve:** between RV and Pulmunary trunk - **Aortic Semilunar valve:** between LV and Aorta **Cardiac Skeleton** - A plate of connective tissue, called the cardiac skeleton, or **fibrous skeleton** consists mainly of fibrous rings that surround the **atrioventricular** and **semilunar valves** and give them solid support. - This connective tissue plate also serves as **electrical insulation** between the atria and the ventricles and provides a **rigid attachment site for cardiac muscle.**  **BLOOD FLOW** **Right Side** -Deoxygenated blood passes through vena cava and into the right atrium -Blood moves from the right atrium to the right ventricle, passing through the tricuspid valve. \- Blood is pumped from the right ventricle and into the pulmonary artery through the pulmonary valve. The pulmonary artery then carries the deoxygenated blood to the lungs. **Left Side** -Oxygenated blood leaves the lungs via the pulmonary vein, which pumps the blood into the left atrium -The blood leaved the left atrium and the passes through the mitral valve into the left ventricle. -The blood pumped from the left ventricle, through the aortic valve and into the aorta. From the aorta, the blood is pumped around the rest of the body. **BLODD SUPPLY TO THE HEART** **Coronary Arteries:** -Supply the blood to the heart wall -Originate from the base of the aorta (above the aortic semilunar valve) **Left Coronary Artery:** \- has 3 branches -Supply blood to anterior heart wall to left ventricle **Right Coronary Artery:** -originates on the right side of aorta -supply blood to right ventricle **Cardiac Veins:** -Drain blood from the cardiac muscle -Parallel to the coronary arteries -most drain blood into the coronary sinus -from the coronary sinus into the right atrium **HEART WALL** **Epicardium** - Surface of the heart **Myocardium** - Thick, middle layer composed of cardia muscle **Endocardium** - smooth, inner surface **CARDIAC MUSCLES** - 1 centrally located nucleus - Branching cells - Rich in mitochondria - Striated (actin and myosin) - Ca2+ and ATP used for contractions - Intercalated disks connect cells **Cardia Muscle Action Potentials** - **Changes in membrane channels' permeability** are responsible for producing action potentials and is called **pacemaker potential.** **1. Depolarization Phase** - **Na+ channels open** - **Ca+2 channels open** **2. Plateau phase** - **Na+ channels close** - **Some K+ channels open** - **Ca2+ channels remain open** **"Plateau phase** prolongs action potential by keeping Ca2+ channels open" **3. Repolarization phase** - **K+ channels are open** - **Ca2+ channels close** - In **Skeletal Muscle** action potential take 2 msec - In **Cardiac Muscle b they take 200-500** msec **CONDUCTION SYSTEM OF HEART** - **Contraction** of the **atria** and **ventricles** is coordinated by specialized **cardiac muscle cells** in the heart wall that form the **conduction system** of the heart - All cells of the conduction systems can produce **spontaneous action potentials.** - **The cardia muscle cells involved in the conduction system:** - **Sinoatrial (SA) node** - In RA - where action potential originates - Functions as pacemaker - Large number of Ca2+ channels - **Atrioventricular (AV) node** - Located in the lower portion of the right atrium - Action potentials from SA node sent to this node - Action potentials spread slowly through it - Slow rate of action potential conduction allows the atria to complete their contraction before action potentials are delivered to the ventricles. - **Atrioventricular (AV) bundle, right and left bundle branches** and; - Action potentials from the AV node travel to AV bundle - AV bundle divides into a left and right bundle branches - **Purkinje** fibers - At the tips pf the left and right bundle branches, are Purkinje fibers - These fibers pass to the apex of the heart and then extend to the cardiac muscle of the ventricle walls - Action potentials are rapidly delivered to all the cardiac muscles of the ventricles **ELECTROCARDIOGRAM(EKG)** - Record of the electrical events in heart - Diagnoses cardiac abnormalities - Uses electrodes - Contains **P wave, QRS** complex **T wave** **P Wave:** -Depolarization of atria **QRS complex:** -Depolarization of ventricles -Contains Q, R, S waves **T Wave** -Repolarization of ventricles **CARDIAC CYCLE** - The cardiac cycle is a summative description of all the events that occur during one single heartbeat - The heart is two-sided pump, with the **atria** being **primers** for pumps and the **ventricles being the actual pumps.** **Atrial Systole:** - Contraction of atria **Ventricular Systole:** - Contraction of ventricles **HEART CHAMBER CONTRACTIONS** - Cardiac Muscles contractions produce **pressure changes** within heart chambers - Pressure changes are responsible for **blood movement** - Blood moves from areas of high to low pressure **HEART SOUNDS** - Heart sounds are produced due to the **closure of heart valves** - A **stethoscope** is used to hear heart sounds - The first heart sound makes a **"lubb",** it is due to the **closure of the atrioventricular valves** - The second heart sound makes a **"dupp",** it is due to the **closure of the semilunar valves** **REGULATION OF HEART FUNCTION** **Stroke Volume:** **-**Volume of blood pumped per ventricle per contraction -70 milliliters/beat **Cardia Output:** **-**Volume of blood pumped by a ventricle in 1 minute -5 liters/ minute -**Stroke volume** (SV) multiplied by **heart rate (HR)** -CO =SV x HR INTRINSIC REGULATION OF THE HEART Starlings Law of the Heart: Preload is a measure of the force that stretches the heart\'s muscle, which is made up of the volume of blood that fills the heart from venous return. The more the muscle is stretched, the further it will contract. After load: Pressure against which ventricles must pump blood. EXTRINSIC REGULATION OF HEART Extrinsic regulation refers to mechanisms external to the heart, such as either nervous or chemical regulation Nervous system control of the heart occurs through the sympathetic and parasympathetic divisions of the autonomic nervous system. Influences of heart activity are carried through the autonomic nervous system. Both sympathetic and parasympathetic nerve fibers innervate the SA node. BARACEPTOR REFLEX The baroreceptor reflex is a mechanism of the nervous system that plays an important role in regulating heart function. Baroreceptors monitor blood pressure in the aorta and carotid arteries; changes in blood pressure cause changes in frequency of action potentials; involves the medulla oblongata. The chemoreceptor reflex involves chemical regulation of the heart. Chemicals can affect heart rate (bpm) and stroke volume. Chemical actions: Epinephrine and norepinephrine from the adrenal medulla can increase heart rate (bpm) and stroke volume. Excitement, anxiety, and anger can increase cardiac output. Depression can decrease cardiac output. Has chemoreceptors for changes in pH and CO2. K+, Ca2+, and Na+ affect cardiac function. **HEART DISEASE** **Coronary Artery Disease** Due to decrease blood supply to the heart. Coronary arteries are narrowed for some reason. **Myocardial Infarction (heart attack)** Due to closure of one or more coronary arteries. Area(s) of cardiac muscle lacking adequate blood supply die, and scars (infarct). **Angioplasty:** A procedure that opens blocked blood vessels. **Coronary artery bypass graft (CABG):** A procedure reroutes blood away from blocked arteries. **THE RESPIRATORY SYSTEM** - **What is the respiratory system** - Consists of the structures used to acquire oxygen (O2) and remove carbon dioxide (CO2) from the blood. - It is a complex system that possesses several airways with different characteristics that conduct the inhaled air until it reaches the alveoli. - This essential function allows trillions of cells making up the body to carry out their cellular functions. - The primary function of the respiratory system is to supply the blood with oxygen and remove carbon dioxide (gas exchange) - It works closely with your circulatory system (heart, blood and blood vessels.) 7 STRUCTURES THAT MAKE UP THE RESPIRATORY SYSTEM ***1.External nose*** - encloses the chamber for air inspiration. ***2.Nasal cavity*** - a cleaning, warming, and humidifying chamber for inspired air. ***3.Pharynx*** - "throat"; serves as shared passageway for food and air. ***4.Larynx*** - "voice box"; keeps the airway constantly open. ***5.Trachea*** - "windpipe"; an air-cleaning tube to funnel inspired air to each lung. ***6.Bronchi*** - tubes that direct air into the lungs ***7.Lungs*** - pair of air tubes and a complex network of air sacs (alveoli), and capillaries **FUNCTIONS OF THE RESPIRATORY SYSTEM** The primary job of the respiratory system is to bring oxygen into the body and remove carbon dioxide (respiration) Breathing consists of two phases: Inspiration -- process of taking in air Expiration -- process of taking out air Functions of the Respiratory System Regulation of blood pH Production of chemical mediators Voice production Olfaction Protection against some microorganisms Main function is respiration. **Ventilation** movement of air into and out of the lungs **Respiration** diffusion of gases across cell membranes **SUBDIVISIONS OF THE AIRWAYS AND ITS STRUCTURES** **Upper Respiratory Tract** Your upper respiratory tract brings air into your body and helps move it toward your lungs. Mainly responsible for filtering, warming, and moistening air. ***1.Nose/Nasal Cavity*** Primary entry point for air. Filters, moistens, and warms the air before it enters the lungs. Contains hair-like structures called cilia that trap dust and particles. ***2.Mouth*** Secondary entry point for air (especially when breathing through the nose isn't possible). Does not filter or warm the air as effectively as the nose ***3. Pharynx (Throat)*** A muscular tube that connects the nose and mouth to the larynx. Divided into three parts: Nasopharynx (upper part, connected to the nasal cavity). Oropharynx (middle part, connected to the mouth). Laryngopharynx (lower part, connected to the larynx). ***4.Larynx (Voice Box)*** Located below the pharynx and above the trachea. Contains the vocal cords that produce sound Acts as a gateway, directing air into the trachea and food into the esophagus Protects the lower airways by producing a cough reflex. **Lower Respiratory Tract** Mainly responsible for transporting air to the lungs and carrying out gas exchange. ***1. Trachea (Windpipe)*** A rigid tube that carries air from the larynx to the bronchi. Supported by cartilage rings to keep it open. Lined with cilia to trap dust and microbes. ***2. Bronchi*** The trachea splits into two main bronchi, one for each lung. Each bronchus further divides into smaller branches, known as bronchioles. Carry air into each lung ***3. Bronchioles*** Smaller air passages that branch out from the bronchi. They lead to the alveoli and are involved in the passage of air to the lungs. Have smooth muscle to help regulate airflow. ***4. Alveoli*** Tiny air sacs at the end of the bronchioles where gas exchange occurs. Oxygen enters the bloodstream, and carbon dioxide is removed. Surrounded by capillaries (small blood vessels). **HOW DOES YOUR RESPIRATORY SYSTEM WORK?** **1.INHALATION (BREATHING IN):** Air enters through the nose or mouth. Oxygen travels down the trachea and into the lungs via the bronchi and bronchioles. The diaphragm contracts and moves downward, expanding the chest cavity and allowing air to flow in. **2.GAS EXCHANGE IN THE ALVEOLI:** In the alveoli, oxygen diffuses across thin membranes into the blood. Carbon dioxide diffuses from the blood into the alveoli to be exhaled **3. OXYGEN TRANSPORT:** Oxygen binds to hemoglobin in red blood cells. Blood circulates oxygen to tissues and organs where it is used to create energy through cellular respiration **4. EXHALATION (BREATHING OUT):** The diaphragm relaxes and moves upward, pushing air out of the lungs. Carbon dioxide is expelled from the lungs through the bronchioles, bronchi, trachea, and out through the nose or mouth. **DIGESTIVE SYSTEM** **I. Introduction to The Digestive System** **Importance and Basic Function** The digestive system is a complex network of organs and structures that work together to break down food into nutrients, which the body uses for energy, growth, and repair. This system is essential for the human body because it transforms food into substances that the body can absorb and utilize. Our bodies consist of cells that require a sufficient supply of nutrients, as these nutrients provide energy for daily activities and support functions such as damage repair, reproduction, and growth. Additionally, the digestive system helps maintain internal homeostasis by regulating fluids and electrolytes, which are crucial for the proper functioning of the body. Digestion begins in the mouth, where food is mechanically broken down into smaller pieces. This process is aided by saliva, which contains enzymes that help chemically break down carbohydrates. After the food is processed in the mouth, it is moved through the esophagus to the stomach. Once in the stomach, food is further broken down by strong acids and enzymes. The stomach also mixes the food into a semi-liquid substance known as chyme. This process prepares the food for more efficient absorption in the small intestine. The majority of the digestion and bulk of the absorption that occurs in the body is carried out in the small intestines while some occurs in the stomach. Glucose, amino acid, and fatty acids are some of the main nutrients which when liberated are transported through the blood to all the bodily cells. At the same moment, the pancreas, liver, and gallbladder release juices along with bile to help the small intestine by enhancing the digestion process and counteracting the acids of the stomach after fats have been emulsified. The large intestine saves part of the remainder including water and some electrolytes resulting in the formation of solid waste. In addition, some bacteria that reside in the large intestine are also helpful as they assist in the digestion of some undigested materials and vitamins such as vitamin K. As a result, the remaining undigested material ends up being expelled through the anus and rectum marking the end of digestion. Processes in the digestive system do not only get energy out of food but also add something to the immune system. The stomach contains specialized cells that act as a shield against harmful pathogens and other foreign bodies. The digestive system along with the stomach acids and enzymes also disrupt harmful bacteria that may be ingested through food. Without a functional digestive system, it would be impossible for the organism to get the right nutrients for nourishment. Alternatively, a breakdown in any section of the system has the potential to cause malnutrition, dehydration, or a whole range of diseases. The digestive system is a complex and well-coordinated system that ensures a supply of nutrients, water, and protection. It is one of the key systems of the body, contributing to the health and the survival. **II.** **Anatomy and Physiology of The Digestive System** **Major Organs and their functions** **A. Alimentary Canal** a\. Mouth Also called the oral cavity, is the first part of the digestive tract. It is adapted to receive food by ingestion, break it into small particles by mastication, and mix it with saliva. The oral cavity contains the teeth and tongue and receives the secretions from the salivary glands. b\. Pharynx Also known as the throat, is the passageway leading from the mouth and nose to the esophagus and larynx. It permits the passage of swallowed solids and liquids into the esophagus, or gullet, and conducts air to and from the trachea, or windpipe, during respiration. c\. Esophagus Approximately 20cm long. Secrete mucus Moves food from the throat to the stomach using muscle movement called peristalsis. If acid from the stomach gets in here it is called heartburn. d\. Stomach J-shaped muscular bag that stores the food you eat, and breaks it down into tiny pieces. Mixes food with Digestive Juices that contain enzymes to break down Proteins and Lipids. Acid (HCL) in the stomach kills bacteria. Chyme- food found in the stomach. Disinfect food, food storage, and digest protein. e\. Small intestine Small intestines are roughly 7 meters long. The lining of the intestine walls has finger-like projections called villi, to increase surface area. The villi are covered in microvilli which further increases the surface area of absorption. Digestion: digests carbohydrates (amylase from the pancreas), proteins (trypsin and chymotrypsin from the pancreas), lipids/fats (bile from the liver and lipase from the pancreas.) Absorption: nutrients move into the body cells by; diffusion and active transport. Absorbs 80% ingested water, vitamins, minerals, carbohydrates, proteins, lipids, and secretes digestive enzymes. Nutrients from the food pass into the bloodstream through the small intestine walls. f\. Large intestine About 1.5 meters long Accepts what small intestines don't absorb. Bacterial digestion: ferment carbohydrates. Absorbs more water and concentrates wastes. Reabsorbs water: use \~9 liters of water every day in digestive juices, if don't reabsorb water, will die of dehydration. \>90% of water re-absorbed leads to diarrhea. Too much water re-absorbed leads to constipation. Rectum: the last section of the large intestine and eliminates feces.  Undigested materials: mainly cellulose from plants, called roughage or fiber. Keeps everything moving and cleans out the intestines. Anus: the opening at the far end of the digestive system tract through which stool leaves the body. **B. Accessory Digestive Organs** a\. Teeth mechanically break down food into small pieces. Tongue mixes food with saliva (contains amylase, which helps break down starch). b\. Tongue muscular organ in the mouth essential for digestion. It manipulates food for chewing, mixes it with saliva for easier swallowing, aids in sound production for communication, and helps maintain an open airway for proper respiration. c\. Liver Directly affects digestion by producing bile. Bile helps digest fats. Filters out toxins and waste including drugs and poisons. d\. Gallbladder Produces bile: breaks up fats, gallbladder only stores bile. Stores bile from the liver and releases it into the small intestine. Fatty diets can cause Gallstones. e\. Pancreas Produces digestive enzymes to digest fats, carbohydrates, and proteins. Regulates blood sugar by producing insulin. Produces digestive enzymes: trypsin and chymotrypsin Digest starch: amylase Digest lipids: lipase Buffers: neutralize acids from the stomach. f\. Salivary glands Saliva contains special enzymes that help digest the starches in food. **III. Digestive Process** [The GI tract is a "disassembly" line]:  - Nutrients become more available to the body in each step There are six essential activities:   a. Ingestion b. Movement c. Mechanical and Chemical Digestion d. Absorption e. Elimination Types ***Mechanical (physical)*** - Chew - Tear - Grind - Mash - Mix ***Chemical*** -Enzymatic reactions to improve digestion of - Carbohydrates - Proteins - Lipids ***Gastrointestinal (Gl) tract*** -Tube within a tube -Direct link/path between organs ***Structures of GI*** - Mouth - Pharynx - Esophagus - Stomach - Small intestine - Large Intestine - Rectum Mouth Functions: **Mechanical Ingestion** - **Teeth** **Chemical Digestion (Saliva)** - amylase enzyme - digests starchmucus **Mucus** - protects soft lining of digestive system - lubricates food for easier swallowing **Buffers** - neutralizes acid to prevent tooth decay **anti-bacterial chemicals** - kill bacteria that enter mouth with food **Teeth** - break up food - Teeth mechanically break down food into small pieces. - Tongue mixes food with saliva (contains amylase, which helps break down starch). - Epiglottis is a flap-like structure at the back of the throat that closes over the trachea preventing food from entering it. It is located in the Pharynx. **Swallowing (& not choking)** - - - - - Functions include: 1. Secrete mucus 2. Moves food from the throat to the stomach using muscle movement called peristalsis - If acid from the stomach gets in here that's heartburn.  - J-shaped muscular bag that stores the food you eat, breaks it down into tiny pieces. - Mixes food with Digestive Juices that contain enzymes to break down **[Proteins and Lipids]**. - Acid (HCl) in the stomach Kills Bacteria. - Food found in the stomach is called Chyme. - hydrochloric acid = pH 2 - kills bacteria - can stretch to fit \~2L food - pepsin enzyme **Small Intestine** - Small intestines are roughly 7 meters long - Lining of intestine walls has finger-like projections called villi, to increase surface area. - The villi are covered in microvilli which further increases surface area for absorption. **Absorption through villi & microvilli** - [finger-like projections] - [increases surface area for absorption] [Functions of SI] *[digestion]* [-digest carbohydrates -(amylase from pancreas)] [-digest proteins- (trypsin & chymotrypsin from pancreas)] [-digest lipids (fats)- (bile from liver & lipase from pancreas)] [Absorption] [-nutrients move into body cells by: (Diffusion and active transport)] - [Nutrients from the food pass into the bloodstream through the small intestine walls.] - *[Absorbs:]* - [80% ingested water] - [Vitamins] - [Minerals] - [Carbohydrates] - [Proteins] - [Lipids] - [Secretes digestive enzymes] [Large Intestine] - [About 1.5 meters long] - [Accepts what small intestines don't absorb] [FUNCTIONS] - [Bacterial digestion] [Ferment carbohydrates] - [Absorbs more water] - [ Concentrate wastes] - [re-absorbs water] [-use \~9 liters of water every day in digestive juices] [-if don't reabsorb water would die of dehydration ] - [\> 90% of water re-absorbed] [-not enough water re-absorbed can cause diarrhea and it can be fatal! ] - [too much water re-absorbed causes constipation] - [reabsorb by diffusion] [Living in the large intestine is a community of helpful bacteria] [-]***Escherichia coli:*** E. coli ***digest cellulose*** -digests fruits & vegetables ***produce vitamins*** -vitamin K & B vitamins ***BUT generate gases*** -by-product of bacterial metabolism -methane, hydrogen sulfide -STINKY! (Fart) **Rectum** - Last section of large intestines -eliminate feces -what's left over? - undigested materials -mainly cellulose from plants \--called roughage or fiber keeps everything moving & cleans out intestines - masses of bacteria **Anus** -is the opening at the far end of the digestive tract through which stool leaves the body. **ACCESSORY ORGANS THE GLANDS** - Not part of the path of food, but play a critical role. - Include: Liver, gall bladder, and pancreas **Liver** - Directly affects digestion by producing bile - Bile helps digest fat filters out toxins and waste including drugs and alcohol and poisons. **Gall Bladder** - Stores bile from the liver, releases it into the small intestine. - Fatty diets can cause gallstones **Pancreas** - Produces digestive enzymes to digest fats, carbohydrates and proteins - Regulates blood sugar by producing Insulin - ***Produces digestive enzymes*** **IV. Disorders and Diseases** The digestive system is a complex network of organs and glands that plays a vital role in breaking down food into essential nutrients. These nutrients are crucial for providing energy, supporting growth, and enabling repair processes throughout the body. The efficiency of this system ensures that the body can maintain optimal health and function. When the digestive system functions properly, it operates through a series of coordinated processes involving mechanical and chemical breakdown of food. Mechanical processes include chewing and the churning of food in the stomach, while chemical processes involve the secretion of digestive enzymes and acids that help to further break down food particles into absorbable nutrients. However, when this intricate system is disrupted, a range of digestive disorders can emerge, affecting not only digestion but also the absorption of vital nutrients. These disorders can result from various factors, including structural abnormalities---such as blockages, ulcers, or inflammatory conditions in the digestive tract---as well as imbalances in digestive enzymes that may impair the breakdown of food. Additionally, improper coordination among the organs involved in digestion can lead to ineffective processing of food. If these digestive issues are not identified and treated promptly. Inadequate nutrient absorption can lead to deficiencies, affecting numerous bodily functions and potentially leading to chronic health problems. Conditions such as malnutrition, anemia, and weakened immune response may arise as a result. The human body relies heavily on the digestive system\'s smooth operation, which is supported by various protective and regulatory mechanisms. These mechanisms are designed to adapt to dietary changes and ensure optimal functioning. However, when these mechanisms become compromised due to stress, illness, lifestyle choices, or other factors, it can create a cascade of challenges that require careful attention and intervention to restore balance and ensure the digestive system operates effectively. Addressing these issues promptly is essential for maintaining overall health and well-being. ***1. Dehydration*** o Dehydration occurs when the loss of fluids exceeds intake, disrupting normal bodily functions. In digestion, dehydration slows the digestive process, hindering the breakdown of food and the absorption of nutrients. This disruption can lead to various digestive issues, ranging from discomfort to severe complications. Proper hydration is essential for maintaining efficient digestion and overall health. o Slowed Digestive Process: Without enough water, the digestive process slows down. This can cause food to move even more slowly through the intestines, leading to issues like bloating and indigestion. o Reduced Enzyme Efficiency: Digestive enzymes require a watery environment to function effectively. Dehydration can reduce their efficiency, making breaking down food and absorbing nutrients harder. o Importance of Hydration for Nutrient Absorption: a\) Water dissolves vitamins, minerals, and other nutrients, making them easier to absorb in the intestines. b\) Adequate hydration ensures that nutrients can be transported efficiently across cell membranes and into the bloodstream. ***2. Diarrhea*** o Diarrhea means having a loose or watery stool (poop). It's so common that most people flinch when they hear the word. The thought of thin, sickly-looking poop in the toilet bowl never stops feeling unpleasant. If you have diarrhea, not knowing what's causing it or how long it'll last only adds stress to the unpleasant feelings. o Diarrhea is mainly caused by: Infections, Food poisoning, medications, and \> 90% of water re-absorbed. a\) Rehydrate: Drink plenty of water, oral rehydration solutions, or electrolyte-rich fluids to prevent dehydration. b\) Adjust diet: Consume easily digestible foods like bananas, rice, applesauce, and toast. c\) Use medications: Take over-the-counter antidiarrheal medicines if recommended, such as loperamide or bismuth subsalicylate. ***3. Constipation*** o It is when a person has difficulty passing stool. It can also cause pain, bloating, nausea, and other symptoms. o Constipation can happen for many reasons, such as when stool passes through the colon too slowly. The slower the food moves through the digestive tract, the more water the colon absorbs, and the harder feces become o Not getting enough dietary fiber may lead to constipation. a\) Drink enough water. b\) Getting enough dietary fiber, aiming for around 22--34g/ day. c\) Choosing the same **time each day to try and have a bowel movement** **URINARY SYSTEM** - The urinary system, also known as the renal system, is a vital part of human physiology. - Its Primary function is to Eliminate the waste of products and maintenance of internal balance (homeostasis). **Components of Urinary System** **1. Kidneys** **2. Ureters** **3. Urinary Bladder** **4. Urethra** **PERFORMING TASKS OF THE URINARY SYSTEM** **1.** Filtering blood. **2**.Separating the toxins you don't need from the nutrients you do need. **3.** Storing and carrying pee out of your body. **STRUCTURE AND FUNCTION** **Kidney** - Also known as Renes or Nephros. - Your kidneys' primary function is to filter your blood. - Basic unit of Kidney: **Nephron** **Functions:** - They clean toxins and waste out of your blood. - Regulates blood volume and pressure - Regulates osmolarity of body fluids - Secretes renin, activates angiotensin, aldosterone \- controls BP, electrolyte balance - Control the acid-base balance of your blood. - Make sugar (glucose) if your blood doesn't have enough sugar. - Make a protein called renin that increases blood pressure. - Produce the hormones calcitriol and erythropoietin ***[Parts of Kidney]*** ***RENAL CAPSULE*** - consists of layers of connective tissue or fat that cover your kidneys. - protects your kidneys from injury ***RENAL ARTERY*** - large blood vessel that controls blood flow into your kidneys. ***RENAL CORTEX*** - outer layer of your kidney where the nephrons begin - creates the hormone erythropoietin (EPO) ***RENAL MEDULLA*** - inner part of your kidney contains most of the nephrons ***RENAL PAPILLA*** - pyramid-shaped structures transfer urine to the ureter ***RENAL PELVIS*** - pyramid-shaped structures transfer urine to the ureter - funnel-shaped structure collects urine and passes it down two ureters ***RENAL VEIN*** - Main blood vessel that carries filtered blood out of your kidneys and back to your heart. ***URETERS*** - These two thin tubes inside your pelvis - Each ureter is about 9 inches long. allows urine to pass outside the body ***URINARY BLADDER*** - Your bladder holds pee until you're ready to empty it. - It's hollow, made of muscle, and shaped like a triangular balloon. - Your bladder expands as it fills up. ***URETHRA*** - This tube carries pee from your bladder out of your - body. - These ring-like muscles open and close to let pee out ***[URINE FORMATION ]*** ***Filtration*** ***-***This occurs in the renal corpuscle. Movement of water, ions, and small molecules through filtration membrane into Bowman's capsule. ***Reabsorption*** -It involves removing substances from the filtrate and placing back into the blood. Proximal tubule is primary site for reabsorption of solutes and water ***Secretion*** -It involves taking substances from the blood at a nephron area other than the renal corpuscle and putting back into the nephron tubule **HORMONAL REGULATION OF RENAL FUNCTION** ***[Renin-Angiotensin-Aldosterone System (RAAS)]*** ***Renin***: \- Produced by the juxtaglomerular cells of the kidney in response to low blood pressure, low sodium, or sympathetic stimulation. \- Converts angiotensinogen (produced by the liver) to angiotensin I. \- Regulate the blood pressure and fluid balance ***Angiotensin II***: \- Formed from angiotensin I via the enzyme ACE (angiotensin-converting enzyme). \- Causes vasoconstriction, stimulates aldosterone secretion, and increases ADH release. \- Effect: Elevates blood pressure and conserves water and sodium. ***[Atrial Natriuretic Hormone (ANH)]*** ***Source:*** Secreted from cardiac muscle in the right atrium of the heart when BP increases ***Function***: Reduces sodium and water reabsorption in the kidneys, inhibits aldosterone and renin release. ***Effect:*** Decreases blood volume and pressure by promoting sodium and water excretion (diuresis). ***[Antidiuretic Hormone (ADH)]*** ***Source:*** Produced by the hypothalamus and released by the posterior pituitary. ***Function***: Increases water reabsorption in the kidneys collecting ducts by inserting aquaporin-2 channels into the duct walls. ***Effect:*** Reduces urine output, dilutes blood, and conserves Water ***[Aldosterone]*** ***Source:*** Secreted by the adrenal cortex (part of the adrenal glands). ***Function:*** Promotes sodium reabsorption and potassium excretion in the distal tubules and collecting ducts ***Effect:*** Increases blood pressure and volume by retaining sodium (and water that follows sodium) **HOMEOSTATIC CONTROL** The homeostatic control of the urinary system involves: - Regulation of fluid and electrolyte balance to ensure hydration and osmotic stability. - Maintenance of acid-base balance for metabolic function. - Waste excretion to detoxify the body. - Hormonal coordination for blood pressure and oxygen delivery **FEMALE REPRODUCTIVE SYSTEM** ***Part I. Introduction*** The female reproductive system is like a team of organs working together to help women have offspring. It\'s important for keeping women healthy too. Its main functions are the following: First, making hormones. The ovaries, which are like small almond-shaped organs, make hormones like estrogen and progesterone. These hormones help girls grow up and become women, and they also help regulate the monthly cycle, which is like a preparation for pregnancy. Second, making eggs. The ovaries also make and release eggs every month. This is called ovulation. Third, fertilization and Pregnancy: If an egg meets sperm, it can become fertilized. Then, the fertilized egg travels through a tube called the fallopian tube and lands in the uterus, which is like a cozy place for the baby to grow. The cervix, which is the opening to the uterus, helps protect the baby during pregnancy. Fourth, menstruation. If the egg doesn\'t get fertilized, the lining of the uterus sheds, which is called menstruation. This is a normal part of the cycle. Lastly, childbirth. When it\'s time for the baby to be born, the uterus contracts, the cervix opens, and the baby comes out through the vagina. The female reproductive system is important because it allows women to create life (offspring). It helps keep women healthy by making hormones that are important for their bodies. It affects how women feel both emotionally and physically. And finally, it helps women live happy and healthy lives. So, the female reproductive system is pretty amazing! It\'s a team of organs that work together to make babies and keep women healthy. **Part II.** ***A. Main Functions of the Female Reproductive System*** 1\. Stores egg cells/ ova and female hormones 2\. Create offspring a\. to allow fertilization to occur b\. to nourish and protect the fertilized egg 3\. Give birth ***B. Internal Parts of the Female Reproductive System*** 1\. Ovaries \- female sex glands \- two rounded organs, one on either side of the uterus \- contains the ova/eggs, and hormones that cause the egg to mature \- ovum: \- egg, female sex cells \- a female is born with hundreds of thousands of immature ova in her ovaries \- from puberty to menopause hormones cause ova mature \- a few hundred will mature during reproductive years 2\. fallopian tubes \- tubes that carry eggs, ova, from ovaries to uterus 3\. fimbriae \- finger-like projections at the end of the fallopian tubes that reach out and "grab" the egg as it leaves the ovary 4\. uterus (womb) \- pear shaped hollow muscular \- organ that receives, holds, and \- nourishes the fertilized ovum during \- pregnancy with thick muscular walls which are \- the thick muscular walls are highly elastic and can stretch many times its normal size. 5\. cervix \- the neck of the uterus, (lower portion) \- protrudes into the top of the vagina \- the passageway between the uterus and the vagina \- site of glands that secrete mucus to lubricate the vagina 6\. vagina \- an elastic, muscular tube that is a passageway between the uterus and the outside of the body, (vulva) \- also called the birth canal \- the female organ for intercourse ***C. External Parts of the Female Reproductive System*** 1\. mons pubis - rounded mass of fatty tissue, covered by skin and pubic hair, that lies over the pubic symphysis. 2\. labia majora (outer lips) 3\. labia minora (inner lips) 4\. vaginal opening 5\. hymen -- thin membrane partially covering the opening of vagina 6\. clitoris -- for pleasure ***D. Ovulation*** \- when a mature ovum (egg), is released from the ovaries it travels along the fallopian tubes to the uterus usually once a month... from one ovary \- an ovum can live about a day in a fallopian tube ***E. Menstruation*** \- the time from one menstruation to another -first day of period to first day of next period \- usually 28 days \- starts at puberty and continues until menopause (due to increase levels of hormones) \- purpose is to prepare the body for fertilization (get ready to have a baby) **Menstrual Cycle** 1\. Days 1-8: menstruation/menstrual period \- about 5-7 days average... not always 2\. Days 9-13: days before the release of egg, hormones cause an egg to mature in one ovary; the body is preparing for egg 3\. Day 14: ovulation... egg is released into one fallopian tube 14 days before menstrual period 4\. Days 15-28: days after egg is released -- egg travel through the fallopian tube to the uterus waiting to be fertilized ***F. Problems of the Female Reproductive System*** 1\. Infertility: \- this is the inability to get pregnant. It may be due to blocked fallopian tubes, a failure to produce eggs, endometriosis, or and STD left untreated. 2\. Ovarian cysts: These are growths on the ovary. Symptoms of ovarian cysts include a feeling of heaviness in the abdomen and abdominal pain, swelling, and bloating. 3\. Infections - Vaginitis \- inflammation of vaginal tissue, Yeast infections \- symptoms: inflammation of vaginal tissue, discharge, burning, itching, and painful urination 4\. Toxic shock syndrome - Associated with tampon use and some contraceptive devises; symptoms include fever, chills, vomiting, diarrhea, rash 5\. Cancer -- Breast -- Cervical 6\. Sexually Transmitted Diseases (STDs) - these are diseases spread through sexual contact. G. Caring for the Female Reproductive System 1\. Practice abstinence from sex - this can prevent infections with HIV and other STDs 2\. Bathe or shower daily - keep the external reproductive organs clean especially during menstruation. 3\. Sanitary pads and tampons should be changed often - every four hours. 4\. Perform self-breast examinations - a way to check your own breast for lumps or tenderness. 5\. Have regular medical checkups -- Pap Test - a physician can answer any question she has Gynecologist. 6\. Get medical attention for signs of infection - lumps, sores, rashes, or a discharge that requires medical attention. 1\. Testes 2\. Ducts 3\. Accessory Glands 4\. Supporting structures ***PENIS*** The penis is used for both urination and sexual intercourse. It is made of spongy tissue and blood vessels. It also contains the urethra which sperm and urine pass through to leave the body. ***TESTES*** -The male reproductive system has two testes. The key roles of the testes include making millions of sperm cells and hormones. -The hormones produced in the testes impact the way a male body develops in puberty. ***FORESKIN*** The foreskin is a retractable fold of skin which covers the end of the penis. ***SCROTUM*** The scrotum is a bag of skin which contains the two testes. ***URETHRA*** The urethra is a hollow tube which transports urine from the bladder to outside the body. It also transports sperm. ***GLANDS*** There are a number of different glands in the male reproductive system. They produce fluids to mix with the sperm which supply the sperm with nutrients and help regulate urine flow (e.g. the prostate gland). ***BLADDER*** The bladder temporarily stores urine in the body. It helps expel urine from the body by sending nerve signals to the nervous system which tells the brain that you need to go to the toilet. ***EPIDIDYMIS*** Epididymis is a coiled tube at the back of the testes. Its main function is to store sperm produced in the testes and to facilitate their maturation. ***DUCTUS DEFERENS*** The ductus deferens is a muscular tube that connects the epididymis to the urethra. It transports mature sperm during ejaculation. ***PREPUCE*** The prepuce is the retractable fold of skin that covers the glans penis. It protects the sensitive glands from abrasion, helps maintain moisture, and contribute to sexual pleasure by lubrication and sensitivity. ***GLANS PENIS*** The glans penis is the rounded, bulbous tip of the penis, which is rich in nerve endings and highly sensitive to touch. The glans is also part of the penis through which semen is ejaculated during sexual activity. ***Functions of the reproductive system*** 1\. Production of sperm cells 2\. Sustaining and transfer of the sperm cells to the female 3\. Production of male sex hormones ***[TESTES AND SPERM PRODUCTION]*** The testes are the primary organs in the male reproductive system that produce sperm and testosterone: ***Function*** The testes are two oval-shaped organs located in the scrotum that produce sperm and testosterone. ***Sperm production*** The testes contain coiled tubes called seminiferous tubules, where sperm production takes place through a process called spermatogenesis. ***Testosterone*** The testes produce testosterone, a hormone that is important for male development and maturation. ***Location*** The spermatic cord holds the testes in place and supplies them with blood ***[SEMINAL FLUIDS AND ITS COMPONENTS]*** Seminal fluid, also known as semen, is a whitish fluid produced by the male reproductive system during ejaculation and is made up of sperm and secretions from accessory glands: ***[Sperm]***: Produced by the testes ***[Seminal vesicles:]*** Produce about 65--75% of the fluid in semen ***[Prostate gland:]*** Produces about 25--30% of the fluid in semen ***[Bulbourethral glands:]*** Contribute a small volume of fluid to semen ***[Other fluids:]*** Contain nutrients, support sperm motility, and help sperm travel through the female reproductive tract ***[Semen also contains:]*** Citric acid, Free amino acids, Fructose, Enzymes, Phosphorylcholine, Prostaglandin, Potassium, and Zinc. The volume of semen in a single ejaculation can range from 1.5 to 6.0 milliliters. A milliliter of semen typically contains 50 to 150 million sperm. ***Semen*** is used for artificial insemination, in vitro fertilization and sperm preservation. ***[EJACULATION PROCESS]*** ***Ejaculation*** is the process of expelling sperm and seminal plasma from the male reproductive system. *[It involves the following steps:]* ***Sperm production***: Sperm are produced in the testes, which are located in the scrotum. ***Sperm storage:*** The epididymis, a coiled structure on top of the testis, receives and stores immature sperm for several days. ***Sperm movement:*** During ejaculation, sperm are forcefully expelled from the epididymis into the deferent duct. ***Sperm and fluid combination:*** The sperm travel through the deferent duct and join with the seminal vesicle to form the ejaculatory duct. The seminal vesicle secretes fluid that nourishes the sperm and helps them move. ***Seminal fluid addition:*** The seminal fluid passes by the prostate gland, where a milky fluid is added to form semen. ***[Ejaculation:]*** The semen is ejaculated through the urethra. Other glands involved in the ejaculation process include: ***Cowper\'s gland:*** Lubricates the urethra and neutralizes acidic urine remnants. ***Bulbourethral and urethral glands***: Pass a small amount of mucus-likesecretion to flush out the urethra. Ejaculation typically starts around the age of puberty, when a person begins producing sperm. It usually happens during a "wet dream" or after masturbating. ***[HORMONAL REGULATION]*** GnRH stimulates LH and FSH release from the anterior pituitary LH stimulates the interstitial cells to produce testosterone FSH stimulates sperm cell formation Inhibin, produced by sustentacular cells, inhibits FSH secretion ***[PUBERTY]*** ❑ Before puberty, small amounts of testosterone inhibit GnRH release ❑ During puberty testosterone does not completely suppress GnRH release, resulting in increased production of FSH, LH, and testosterone. ***[EFFECTS OF TESTOSTERONE]*** ❑ Causes the development of male sex organs in the embryo ❑ Stimulates the descent of the testes ❑ Causes enlargement of the genitalia ❑ Necessary for sperm cell formation ❑ Hair growth stimulation (pubic area, axilla, and beard) and inhibition (male pattern baldness) ❑ Increased skin thickness and melanin and sebum production ❑ Enlargement of the larynx and deepening of the voice ❑ Increased protein synthesis (muscle), bone growth, blood cell synthesis, and blood volume ❑ Metabolic rate increases ***[MALE SEXUAL BEHAVIOR AND THE MALE SEXUAL ACT]*** ❑ Testosterone is required for normal sex drive ❑ The male sexual act includes: ▪Erection--- Engorgement of penis ▪Emission--- the discharge of semen from the ducta deferentia into the urethra ▪Ejaculation- forceful expulsion of semen ❑ The male sexual act includes: ▪Orgasm--- Sensations that are normally interpreted as pleasurable and result in a climactic sensation ▪Resolution--- characterized by a flaccid penis, an overall feeling of satisfaction, and the inability to achieve erection and a second ejaculation for a period of time ❑ Stimulation of the sexual act can be psychic or tactile ***[DISEASES THAT CAN AFFECT THE MALE REPRODUCTIVE SYSTEM]*** **[Testicular cancer]**: Most commonly affects men between the ages of 15 and 45. **[Prostate disease:]** Includes benign prostatic hyperplasia (BPH), which is swelling of the prostate gland, and prostate cancer. **[Infertility:]** Can be caused by low sperm production, blockages, or other factors. **[Erectile dysfunction:]** A problem with getting or keeping an erection. **[Sexually transmitted infections (STIs):]** Bacterial or viral infections acquired through sexual contact. **[Premature ejaculation:]** A common condition that affects the male reproductive system. **[Cryptorchidism:]** One or both testes do not descend into the scrotum. **[Herpes:]** A genital HSV-1 infection can occur when a person receives oral sex from a person with an HSV-1 oral ulcer. \*Other conditions that can affect the male reproductive system include: Penile cancer, Priapism, and Male hypogonadism. ***[THINGS TO DO TO CARE FOR YOUR MALE REPRODUCTIVE SYSTEM]*** ➔ Practice safe sex ➔ Perform self-examinations ➔ Get regular prostate exams ➔ Maintain a healthy weight ➔ Practice good hygiene ➔ Get the human papilloma virus (HPV) vaccine ➔ Consider circumcision ***[BRAIN'S ROLE IN MALE REPRODUCTIVE SYSTEM]*** Hormone production --- The hypothalamus, located in the central brain, produces gonadotropin-releasing hormone (GnRH), which regulates the production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the pituitary gland. These hormones are involved in both male and female reproduction. Sexual response --- The brain controls sexual response through a series of neural events that regulate libido, motivation, arousal, and genital responses. These events involve the hypothalamus, septum, bed nucleus of the stria terminalis (BST), hippocampus, amygdala, and olfactory systems. Connection between the brain and the male reproductive tract --- Neurons may send molecular information to the male reproductive tract, which could mean that the brain interprets environmental conditions to program sperm.