Human Body Systems. Regulation and Homeostasis in the Human Body: Overview.

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. Lymphatic 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 Bodyis composed of

Organ Systemsare composed of

Organsare composed of

Tissuesare composed of

Cells

Circulatory System

Major Structures• heart, blood vessels,

blood, lymph nodes and vessels, lymph

Functions• transports nutrients,

wastes, hormones, and gases

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.

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.

Digestive System

Major Structures• mouth, throat,

esophagus, stomach, liver, pancreas, small and large intestines

Functions• extracts and absorbs

nutrients from food; removes wastes; maintains water and chemical balances

The nutrients your body needs are water, carbohydrates, fats, proteins, vitamins and minerals.

WATER – Most of the bodies reactions take place in water. Humans need an average of 1 liter of water a day. Dehydration causes many problems throughout the body.

CARBOHYDRATES – Sugars and starches are used by the body to provide the simple sugars needed for Respiration (energy)

FATS- Deposits of fats protect body organs, insulate the body and store energy, make up cell membranes and coat the nervous system cells

PROTEINS – Supply the raw materials for growth and repair in the form of enzymes

VITAMINS – Organic molecules that work with enzymes to control body processes.

MINERALS – Inorganic nutrients that are needed in small amounts. Calcium is needed to build bones, Iron is needed for red blood cells.

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

Section 38-2

As food leaves the stomach it travels into the small intestine through the doudenum, and it mixes with with enzymes and digestive fluids from the liver, gallbladder and pancreas.

Liver

Gallbladder

Doudenum

Bile Duct

Pancreas

. Chemicals from the pancreas breakdown carbohydrates, proteins, lipids and nucleic acids. In addition chemicals from the pancreas produce substances which neutralize stomach acid.

If the acid travels too far without being neutralized it will change the shape of enzymes and cause problems in the body.

The Liver makes bile which acts like a detergent to break down fat. The gall bladder is a storage area for the bile

Small Intestine

Villus

Section 38-2

The small intestine absorbs nutrients from the digestive systems and transfers many of the nutrients to the circulatory system. The small intestine is lined with small fingerlike projections known as villi which designed to have a large surface area for this task.

Large intestine (Colon)

Food that enters the large intestine is nutrient-free. Usable nutrients have been absorbed leaving water and undigestible substances. The large intestine removes water from the waste. Once water is eliminated the solid waste passes out of the body through the rectum.

The appendix is located just below the entry to the large intestine. In many animals it helps digest difficult materials such as cellulose. In humans the appendix is not used for any purpose in digestion. When

it gets infected it is removed.

Endocrine System

Major Structures• hypothalamus, pituitary,

pancreas, pineal, adrenal, thyroid, parathyroid, testes, and ovaries

Functions• regulates body

temperature, metabolism, development, and reproduction; maintains homeostasis; regulates other organ systems

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.

Examples of functions controlled 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.

Room temperature increases

Thermostat senses temperature change and switches on heating system

Thermostat senses temperature change and switches off heating system

Room temperature decreases

Section 35-1

Example of Feedback Loop

Beta cells release insulin into the blood

Body cells absorb glucose

Blood glucose level decreases

Homeostasis: Normal blood glucose level

Blood glucose level decreases

Alpha cells release glucagon into blood

Liver converts glycogen to glucose

Blood glucose level increases

Blood glucose level increases

Liver converts glycogen to glucose

Feedback Actions of Insulin and Glucagon

Hypothalamus

Pituitary

Parathyroids

Thymus

Adrenal Glands

Pineal Gland

Thyroid

Pancreas

Ovary (female)

Testis (male)

Important Glands and Hormones of the Human Body

Gland Hormone Function

Pineal Melatonin Controls sleep and wake cycle

Thyroid Thyroxine Controls appetite and metabolism

Adrenal Adrenaline Deals with stressful situations

Thymus Thymosin T-cell development (fight diseases)

Ovary Estrogen Female reproduction

Testis Testosterone Male reproduction

Excretory System

Major Structures• kidneys, urinary bladder,

ureters, urethra, skin, lungs

Functions• removes wastes from

blood; regulates concentration of body fluids


• 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.

KidneyNephron

Section 38-3

Kidneys contain millions of small filters called nephrons, which filter your entire blood supply every 45 minutes. Filtration takes place because blood pressure forces water, salt, glucose, amino acids and urea into structures known as Bowman’s capsules. (Protein and Blood are too large to enter)

Bowman’s Capsule

Processes of osmosis and active transport filter the useful materials from the waste (urine). Substances your body needs to keep are returned to the blood stream. Substances your body needs to get rid of are passed from the renal tubes to the urinary bladder.

Kidney

Urinary Bladder

Ureter

Urethra

Vein Artery

Immune System

• Structures: White blood cells, thymus, spleen, lymph nodes, lymph vessels

• Function: Helps protect the body from disease; collects fluid lost from blood vessels; returns the fluid to the circulatory system

Lymphatic System – Immune System

Structures: White blood cells, thymus, spleen, lymph nodes, lymph vessels

Function: Helps protect the body from disease; collects fluid lost from blood vessels; returns the fluid to the circulatory system


• 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.

Integumentary System

Major Structures• skin, nails, hair

Functions• protects against injury,

infection, and fluid loss; helps regulate body temperature


• 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.

Skeletal System

Major Structures• bones and joints

Functions• protects and supports

the body and organs; interacts with skeletal muscles; produces red blood cells, white blood cells, and platelets


• 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).

Muscular SystemMajor 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. Functions• moves limbs and trunk; moves substances

through body; provides structure and support


• 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 O2, 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 36-7 Skeletal Muscle Structure

Section 36-2Skeletal muscles are made up of clusters of filaments of proteins known as actin and myosin which control muscle contraction and relaxation

Figure 36-8 Muscle Contraction

During Muscle contraction Actin filaments slide over myosin filaments shrinking the muscle

Energy for muscle contraction is supplied by ATP

Nervous system cells known as motor neurons are attached to skeletal muscle cells to control the voluntary movement.

Threadlike Nerve or neuron

Axon or junction

Movement

Movement

Biceps (relaxed)

Triceps (contracted)

Biceps (contracted)

Triceps (relaxed)

Figure 36-11 Opposing Muscle Pairs

Section 36-2Skeletal muscles work in opposing pairs. When one muscle contracts, the other relaxes.

Nervous System

Major Structures• brain, spinal cord, nerves,

sense organs

Functions• regulates behavior;

maintains homeostasis; regulates other organ systems; controls sensory and motor functions


• 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.

Axon terminals

Nodes

Myelin Sheath

Cell Body

Nucleus

Dendrites

NEURON CELL

Once and impulse begins it moves along the axon in the direction of the impulse. To pass between neurons the impulse must be sent across a gap known as a synapse which sends the message from one neuron to the other. When the impulse reaches the end of the axon it transfers its impulse to another cell by releasing chemicals known as neurotransmitters which pass the message across the synapse.

Synapse

The nervous system is divided into two divisions:

• The Central Nervous System (CNS)– Responsible for relaying messages, processing and analyzing information.

• The Peripheral Nervous System – Receives information from the environment and relays commands from the CNS to the organs and glands

Cerebrum

Thalamus

Hypothalamus

Pituitary Gland

Pineal Gland

Cerebellum

Spinal Cord

Pons

Medulla oblongata

The Brain

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.

Reproductive System

Major Structures• ovaries, uterus, and

breasts (in females); testes and penis (in males)

Functions• produces gametes and

offspring


• 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.

Respiratory System

Major Structures• lungs, nose, mouth,

trachea

Functions• moves air into and out of

lungs; controls gas exchange between blood and lungs


• 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 O2 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.

Section 37-3

Figure 37-13 The Respiratory System

Bronchi branch to air sacs known as aveoli where gas exchange occurs

The Respiratory System links to the Circulatory System to provide cells with oxygen and remove carbon dioxide

Alveoli

Bronchiole

Capillary

Section 37-3

Gas Exchange in the lungs occurs through the process of

DIFFUSION

High concentration of oxygen (O2) moves out of lungs into blood to balance concentration. CO2 does the opposite (moves from blood to lungs)

Air inhaled

Diaphragm

Rib cage rises

Air exhaled

Diaphragm

Rib cage lowers

Inhalation

Exhalation

Section 37-3

Figure 37-15 The Mechanics of BreathingThe Lungs are only air sacs. In order for them to move they must work together with a muscle known as the Diaphragm

Breathing is not an entirely voluntary process. While you have control of breathing so that you can briefly hold your breath or blow up a balloon, your body will not allow you not to breathe. The brain has control over the diaphragm if the level of carbon dioxide in the blood rises to high.

Human Body Systems. Regulation and Homeostasis in the Human Body: Overview.

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