Human Body Systems Regulation and Homeostasis in the

Human Body Systems

Regulation and Homeostasis in the Human Body: Overview

How do Humans and other complex mammals maintain homeostasis? They must carry out all needed life functions in a coordinated way. What does our species need to accomplish? Growth Repair of injuries Get energy Get building materials Get rid of waste Keep away disease Respond to changing environment Reproduce

Eleven Body Systems work together to maintain homeostasis and carry out these tasks: 1. Nervous System 2. Endocrine System 3. Immune System 4. Circulatory System 5. Respiratory System 6. Digestive System 7. Excretory System 8. Skeletal System 9. Muscular System 10. Integumentary System 11. Reproductive System

Human Body Organization The Human Body is composed of Organ Systems are composed of Organs are composed of Tissues are composed of Cells

Integumentary System Functions • protects against injury, infection, and fluid loss; helps regulate body temperature Major Structures • skin, nails, hair

Interesting Facts… • Skin cells are made of a tough protein called keratin. • About 40 million dead skin cells are lost each day. • The average adult skin spread out would take up about 2. 2 square yards and would weigh around 15 pounds. • The skin is waterproof. It keeps water out so the body is not a sponge and holds in moisture so it does not dry out. • Skin expands to fit the body. • Skin forms bumps when cold and releases sweat when hot. • The skin repairs itself forming scabs and scars. • Skin absorbs sunlight to make vitamin D. Too much sun can lead to sunburn and can even cause skin cancer.

How does the human body move from place to place and have the ability to run, blink or build things? These things are all made possible by the skeletal and muscular systems.

Muscular System Functions • moves limbs and trunk; moves substances through body; provides structure and support Major Structures • Skeletal – Attached to bones for voluntary actions and controlled by the central nervous system • Smooth – Found in the digestive tract and the blood vessels to move food and blood. Control involuntary actions (you do not decide for them to work) • Cardiac – Heart muscle cells are involuntary.

Interesting Facts… • There are nearly 600 skeletal muscles that make up nearly half of the total body weight in the human. • Muscles can only pull – they cannot push. • Energy is stored in the muscles in a chemical called ATP. • Lactic acid is released when the muscles are overworked and lack O 2, making the muscles hurt or ache. • Muscles are attached to bones by tendons. • The biggest muscles in the body are the gluteus maximus muscles (buttocks), but the muscle that can exert the most force is the masseter (jaw muscle).

Figure 36 -11 Opposing Muscle Pairs Skeletal Section 36 -2 muscles work in opposing pairs. When one muscle contracts, the other relaxes. Movement Biceps (relaxed) Movement Triceps (contracted) Biceps (contracted) Triceps (relaxed)

Skeletal System Functions • protects and supports the body and organs; interacts with skeletal muscles; produces red blood cells, white blood cells, and platelets Major Structures • bones and joints

Interesting Facts… • A baby is born with 270 bones while an adult body has 206 bones. • The hands and feet contain half of the bones in the human body. • Bones are made of the hard mineral calcium, living cells, blood vessels and nerves. • Bones are made of several layers – periosteum, compact bone, and spongy bone. • A joint is where two bones meet. • Joints can be cartilagenous (spine), ball-and-socket (shoulders and hips), pivot (neck), gliding (wrists), and hinged (fingers, elbows, and knees).

Nervous System Functions • regulates behavior; maintains homeostasis; help you control your body and to respond to you environment Major Structures • brain, spinal cord, nerves, sense organs

Interesting Facts… • The left half of the brain controls the right half of the body and vice-versa. • The human brain is more powerful and complicated than the world’s biggest computer. It can store millions of memories and do billions of calculations every day. • The human body has over 100 billion neurons in all. • The brain can receive over 100, 000 signals per second. • Messages whiz through the nerves at up to 270 mph. • Neurons reaching from the spinal cord to the toes are the longest cells in the human body, measuring up to 4 feet in length.

The Nervous System: The nervous system is the number one communication center of the body. The basic cell type that carries the communications is a network of neurons that transmit electrical impulses across the synapse-gap between neurons. NEURON CELL Nucleus Axon terminals Cell Body Myelin Sheath Nodes Dendrites

The Brain Cerebrum Thalamus Pineal Gland Hypothalamus Cerebellum Pituitary Gland Pons Spinal Cord Medulla oblongata

The brain is the main switching area of the central nervous system. Cerebrum – Responsible for voluntary activities of the body (Intelligence, learning and judgement) Cerebellum – Coordinates muscle movement Brain Stem – Consists of the pons and the medulla oblongata. Pass message between brain and body Thalamus – Connects messages from the sense organs to the Cerebrum Hypothalamus - Control center for hunger, thirst, anger and body temperature.

Digestive System Functions • extracts and absorbs nutrients from food; removes wastes; maintains water and chemical balances Major Structures • mouth, throat, esophagus, stomach, liver, pancreas, small and large intestines

Interesting Facts… • Food takes 3 days to complete its journey through the digestive system. • An adult digestive system is about 30 feet long. • An average person takes in about 4. 4 pounds of food and drink every day, consuming over 110, 000 pounds in a lifetime. • Gravity and bands of muscles help food travel down the esophagus to the stomach, making it possible to eat lying down or even upside down. • The stomach is lined with a slimy mucus and releases an acid called gastric juice to help dissolve food. • Stomach noises are caused by food and air sloshing around. • Water makes up about 70% of the body.

The Process of Digestion: The path of food Each organ of the digestive system helps convert foods into simpler molecules that can be absorbed and used by the cells of the body. Teeth – Cut, Crush and tear food Salivary glands – Moisten food to make it easier to chew and pass through the system, enzymes break down starches Esophagus – Tube from mouth to stomach connected by Pharynx. Works by contraction of the smooth muscles known as peristalsis. Stomach – Muscular sac that churns and mixes food with acid

Excretory System Functions • removes wastes from blood; regulates concentration of body fluids Major Structures • kidneys, urinary bladder, ureters, urethra, skin, lungs

Interesting Facts… • Leftover waste in the large intestine is called fiber. Fiber sweeps the digestive system clean as it moves along. • The large intestine contains millions of bacteria that feed on the leftovers in the bowel. • Kidneys are located in the middle of the back. • Each kidney contains up to a million tiny units called nephrons that filter all of the blood in the body. • People with failing kidneys have their blood cleaned by a dialysis machine or have a new kidney transplanted.

Circulatory System Functions • transports nutrients, wastes, hormones, and gases Major Structures • heart, blood vessels, blood, lymph nodes and vessels, lymph

Interesting Facts… • The heart is a muscle about the size of a fist. • Each blood cell takes around 20 seconds to make its deliveries and travel back to the heart. • The heart works by contracting and relaxing. • The heart has flapping valves that allow blood to flow in one direction. The flaps create a “lub-dup” sound. • A heart attack is caused by a blood vessel blocked by a clot. • The average person has about 5 liters of blood. • The body can replace blood within a few weeks after loss. • Platelets in the blood help it to clot, or stick together, to make scabs. • The four blood types are A, B, AB, and O.

Respiratory System Functions • moves air into and out of lungs; controls gas exchange between blood and lungs Major Structures • lungs, nose, mouth, trachea

Interesting Facts… • The lungs fill up most of the chest cavity. • The left lung is slightly smaller than the right lung, because it must allow enough space for the heart. • Inside each lung is a network of thousands of tunnels called the bronchial tree which branch into bronchioles containing six million tiny bags (air sacs) called alveoli. • The lungs take millions of O 2 molecules out of the air and put them into the blood to be delivered to the cells. • Simultaneously, the lungs also take waste gases out of the blood. • A smoker’s lungs are dark gray and full of dirt and tar.

The Respiratory System to the. System Figure 37 -13 Thelinks Respiratory Circulatory System to provide cells with Section 37 -3 oxygen and remove carbon dioxide Bronchi branch to air sacs known as aveoli where gas exchange occurs

Gas Exchange 37 -3 in the. Section lungs occurs through the process of DIFFUSION Alveoli Bronchiole High concentration of oxygen (O 2) moves out of lungs into blood to balance concentration. CO 2 does the opposite (moves from blood to Capillary

The Lungs are only 37 -15 air sacs. In order for them Figure The Mechanics of Breathing to move they must work together with a Section 37 -3 muscle known as the Diaphragm Air inhaled Air exhaled Rib cage lowers Rib cage rises Diaphragm Exhalation Inhalation

Endocrine System Functions • Controls growth, development, metabolism and reproduction through the production and secretion of hormones Major Structures • hypothalamus, pituitary, pancreas, pineal, adrenal, thyroid, parathyroid, testes, and ovaries

Interesting Facts… • Endocrine glands release hormones, chemicals that act as signals telling different parts of the body what to do. • The body makes over 20 hormones, each with a different job to do. • The blood carries hormones around the body until reaching the target organ, the body part needing it. • Hormones can affect the way a person feels. • As a person ages, the body makes less of some hormones.

The Endocrine System Sends messages throughout the body by way of chemicals known as hormones. Hormones travel throughout the bloodstream to target cells which contain matching receptors. Hormone Receptor

If a cell does not have a specific receptor the hormone will not affect the cell. Responses to hormones take longer and last longer than nervous system messages. Hormones can take minutes, hours or days to influence cells. controlled Examples of functions by hormones: Growth, Metabolism, Sleep, Reaction to stress, Reproduction.

The Endocrine System works through a FEEDBACK system. Glands of the Endocrine system determine the level of a hormone in the blood and then changes the rate of hormone production or sends out the opposite hormone to counteract excess amounts of hormone. Examples of Feedback mechanisms: Control of insulin/sugar levels in blood Hypothalamus can measure water level in blood and sends out hormones that tell the kidneys to conserve water.

Hypothalamu s Pituitary Parathyroid s Pineal Gland Thyroid Pancreas Ovary (female) Thymus Adrenal Glands Testis (male)

Important Glands and Hormones of the Human Body Gland Pineal Hormone Melatonin Thyroid Thyroxine Adrenaline Thymus Thymosin Ovary Estrogen Function Controls sleep and wake cycle Controls appetite and metabolism Deals with stressful situations T-cell development (fight diseases) Female reproduction Testis Testosterone Male reproduction

Reproductive System Functions • produces gametes and offspring Major Structures • ovaries, uterus, and breasts (in females); testes and penis (in males)

Interesting Facts… • A person grows over 5 million times bigger changing from a single cell to a newborn human being. • Humans grow for about 20 years, changing from a child to an adult. • Male reproductive cells are called sperm, and female reproductive cells are called eggs. • Sperm and eggs have only 23 chromosomes each. • When joined together, sperm and egg make a whole cell called a fertilized egg which can grow into a baby.

The Reproductive System Functions to make new individuals by producing, storing and releasing specialized sex cells known as gametes. Cells from the male reproductive system, known as sperm, must fuse with cells of the female reproductive system, known as eggs.

Reproduction in both males and females is regulated by hormones. • In males - Testosterone is produced by the testes. It is required for sperm production and development of male physical characteristics. • In females - Estrogen and progesterone are female hormones produced by the ovaries. Estrogen is required for the development of eggs and female physical characteristics. Progesterone prepare the uterus for the arrival of a developing embryo.

Immune System Function: Helps protect the body from disease; collects fluid lost from blood vessels; returns the fluid to the circulatory system Structures: White blood cells, thymus, spleen, lymph nodes, lymph vessels

Interesting Facts… • The immune system is constantly on guard to keep germs, bugs, and poisons out the body. • The skin is the immune system’s first line of defense. • There are germ-killing chemicals in saliva, tears, ear wax, and mucus. • White blood cells destroy germs that enter through cuts. • Sticky yellow pus is made of bodies of white blood cells that die in the battle against germs. • An allergy is the immune system making a mistake. • Some white blood cells make antibodies which can protect against bacteria, viruses, and poisons.