The Human Body 7 th Grade Life Science Schley County Middle School Coach Blocker.

The Human Body

7th Grade Life Science

Schley County Middle School

Coach Blocker

S7L2. Students will describe the structure and function of cells, tissues, organs, and organ systems.

e. Explain the purpose of the major organ systems in the human body (i.e., digestion, respiration, reproduction, circulation, excretion, movement, control, and coordination, and for protection from disease).

Body Organization

Bodies must maintain homeostasis, a stable internal environment, in order to surviveCells form tissues, tissues form organs, organs form organ systems, organ systems form the organismFour Types of Body Tissue Epithelial – covers and protects under layers of tissue – stick

tightly together forming a continuous sheet Nervous – sends electrical signals through body Muscle – cells that can contract and relax to produce

movement Connective – joins, supports, protects, insulates, nourishes,

and cushions organs

Skeletal System

Approximately 206 bones in body

FunctionsProtects internal organs (heart, lungs, spinal cord, and brain)

Stores minerals for proper functioning and fat for energy (Calcium and phosphorus)

Anchors muscles to produce movement

Makes blood cells in the marrow

Gives organisms body shape and support

Skeletal System

Bones are organs with living tissueOsteocytes – mature bone cellsOsteoblasts – deposit minerals in bones (Build bone)Osteoclasts – dissolve bone (break down bone)Compact bone – hard inner structureSpongy bone – many open spaces – provides most of the strength and support Marrow – soft tissue inside bones Red marrow produces red blood

cells Yellow marrow stores fat, and

produces white blood cells

Skeletal System

Bones begin as cartilage – soft flexible tissue and is replaced by bone as you grow

Joint – place where 2 or more bones come together

1. Fixed (immoveable) joints

allow no movement – plates in skull

2. Moveable joints

have wide range of movement – these are more susceptible to injury (4 types)

Ligaments – connect bones for movement

Strained ligaments heal – torn ligaments need surgery

Cartilage between bones wears away causing arthritis

Skeletal System

4 Types of Moveable JointsGliding or Sliding – allow hands, feet and back bones to glide over one anotherBall and socket – allows movement in all directions – shoulder and

hipHinge – flex joint about 180 degrees – knees, elbows, fingers, toesPivot – allows rotation at a fix point – skull on spine



Muscular SystemMuscle is the major organ of the muscular system.

There are over 600 muscles in the human body.

The function of muscle is to create movement.

Three types of muscle tissue Smooth – digestive tract and blood vessels Cardiac – heart Skeletal – attached to bones for movement

Tendons – connect muscles to bones

Voluntary muscles – under your control – hand/arm/leg movement

Involuntary muscles – not under control – heartbeat, blinking, breathing

Muscular System

The brain sends electrical signals to muscles – muscles respond by contracting or relaxing.Muscles work in pairs – while one muscle is contracting (shortening) another is relaxing (elongating).Resistance exercises – most effective – overcome weight of another object.

Hypertrophy – muscle increase in sizeAtrophy – muscle decrease in size

Aerobic exercises – strengthens the heart and increases endurance.

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Integumentary System

Major organs are skin, hair, and nails; Skin is the largest organ of the human body

Functions

1. Protection—forms a protective covering over the body that prevents injury

a. Many disease-causing organisms cannot pass through the skin.

b. Prevents excess water loss

2. Sensory response - nerve cells in the skin detect and relay information to the brain

3. Formation of vitamin D, which helps your body absorb calcium

4. Regulation of body temperature

a. Blood vessels in the skin help release or hold heat.

b. Perspiration from the sweat glands eliminates excess heat that has been produced by muscle contractions.

5. Elimination of wastes through sweat glands


Skin – made of three major layers Epidermis – thin outside layer

of skin – most cells are dead epithelial tissue and contain keratin which makes skin tough

Dermis – thick inside layer of skin – connective tissue made of collagen – provides strength and the ability to bend without tearing

Subcutaneous Layer – fatty layer


Blood vessels – regulate body temp

Nerves – carry messages to and from brain

Muscle fiber – contracts the hair causing it to stand up

Hair follicles – produce hair

Oil glands – release oil to keep flexible – waterproofs the epidermis

Sweat glands – cools skin and removes waste


Melanocytes – skin cells that produce melanin which determines skin color – more melanin darker the skin – absorbs harmful radiation

Hair follicle – new cells added to bottom and older cells push upward

Hair protects from ultraviolet light, protects from dust and insects, and help regulate body temperature

Nails protect tips of fingers and toes – form from base and sides

Skin Cancer – uncontrolled cell division in skin



Digestive System

Accessory organs (food does not pass through)TeethSalivary glandsLiverPancreasGall bladder

Major organs (food passes through)MouthThroatEsophagusStomachSmall intestinesLarge IntestinesRectum and Anus

Digestive System

Major Functions:Digestion of foodAbsorption of nutrients – Water, protein, carbohydrates, fats, vitamins, and mineralsElimination of waste

Digestive System

Two Types of DigestionMechanical Digestion – crushing of food into smaller moleculesChemical Digestion – molecules broken down into nutrients Enzymes – breaks down nutrients

into smaller particles

Digestive System

Teeth – break and grind food – made of enamelSalivary gland – makes saliva that begins chemical digestion of carbohydrates – saliva contains enzymesMouth – opening into the digestive system – begins mechanical and chemical digestionThroat – back of the mouth where peristalsis begins – epiglottis is the protective cartilage that covers larynx as food and liquids pass through esophagus.Esophagus – transports food to stomach using peristalsis – squeezing through with muscle contractions.

Digestive System

Stomach – produces gastric juice – enzymes and hydrochloric acid to kill bacteria and break food down – converts food into chyme – a soupy mixture

Small Intestine – connected to stomach – mixes chyme with (bile) a green fluid from liver and pancreatic juice – most chemical digestion takes place here – and the absorption of nutrients by diffusion Villi – fingerlike projections in small

intestines that contain nutrient-absorbing cells – send nutrients to blood stream

Bacteria in the small intestines help to clean small intestines and digest fiber

Digestive System

Pancreas – makes pancreatic juice containing bicarbonates that neutralized the acid in chyme – also makes hormones to regulate blood sugar

Liver – makes bile to digest large fat molecules– stores nutrients – breaks down toxic substances – makes cholesterol

Gallbladder – stores bile from liver and transports it to the small intestine

Large Intestine – processes material that was not absorbed in small intestine – reabsorbs most water and compacts solid mass called feces or stool – bacteria live in large intestines and process vitamins

Rectum stores feces till it passes out the anus

Digestive System

Problems That May Occur in the Digestive SystemHeartburn – sphincters (muscles) block off stomach from backflow of stomach acid – when it does backflow it causes the burning pain in chest

Constipation – when bowel movements become difficult and infrequent due to lack of water/fiber in stool

Diarrhea – when bowel movements are frequent and water is not removed from stool

Colon Cancer – uncontrolled cell division in colon

Gastric Ulcer - an open sore in the stomach lining

Warm-Up (5 minutes)

Describe, step by step, what happens to an apple, from first bite to end products, as it is digested in the body. Use proper vocabulary!

Warm-Up

In the mouth, the tongue and teeth begin mechanical degestion to break the apple down into smaller particles. Saliva, which contains the enzyme amylase, begins chemical digestion, breaking down starch into sugar. Then, through peristalsis, the esophagus moves the apple particles into the stomach. In the stomach, food is mixed mechanically by peristalsis. It is also broken down by acids with the help of enzymes and changed into chyme. The chyme flows into the small intestine, where it is further digested chemically, as bile and pancreatic juice are mixed with the chyme. Nutrients are absorbed by the villi in the small intestines into blood vessels, and then transported to all the cells of the body. The remaining undigested materials move into the large intestine, where water is absorbed from it, and it becomes more solid. Finally, the rectum and anus control the release of the remaining solid wastes.



Cardiovascular System (Circulatory System)

Major organs – heart, blood, and blood vessels

FunctionsTransports oxygenated blood and nutrients to the cells and takes away waste from the cells.Transports waste materials away from cells

Blood vessels - hollow tubes that transport blood Arteries – take blood away

from the heart – they have thick walls to handle the pressure and this is where you feel your pulse

Capillaries – allows material to diffuse through the wall to cells and back

Veins – take blood back to heart



Blood – connective tissue that is made of red blood cells, white blood cells, and platelets that float in plasma – the liquid part of bloodRed blood cells supply oxygen RBC’s contain hemoglobin

– protein that clings to oxygen

RBC’s are made in the red bone marrow and replaced every 4 months

White blood cells – destroy pathogensWBC’s surround the pathogen and destroy it or they release antibodies – chemicals that destroy them.WBC’s made in yellow bone marrow and in lymphatic organsPlatelets – clot blood by clumping together in damaged area to prevent blood loss – made in bone marrow and only live 5-10 days


The heart pumps blood to the lungs then through the bodyHeart has 4 chambers Upper chambers are called

atria (atrium singular) Lower chambers are called

ventricles

The right and left side of the heart are separated by the septum


Three Types of Circulation

Pulmonary circulation – when blood is transported from the heart to the lungs, then back to the heart

Systemic Circulation – when blood is transported from the heart to the rest of the body Coronary Circulation – blood

transported throughout the heart itself


Blood pressure – is the force exerted by blood on the blood vessel Systolic pressure – first number – pressure in arteries when ventricles

contract Diastolic pressure – second number – pressure in arteries when ventricles

relax

4 blood types Type A – A antigens Type B – B antigens Type AB has both antigens – can get any type of blood –

universal recipient Type O has neither antigen – can be given to anyone –

universal donor


Disorders of the Circulatory System

Atherosclerosis – when cholesterol builds up inside blood vessels – become narrower and less elastic – causes heart attacks

Hypertension – abnormally high blood pressure

Stroke - when blood vessels in the brain become clogged or rupture


Lymphatic System

Collects excess fluids and returns them to the blood stream and fights pathogensLymph capillaries – absorb fluid and particles too large for capillariesLymphatic vessels – larger vessels with valves to prevent backflowLymph – fluid and particles absorbed by the lymph capillaries

Lymphatic System

Lymph Nodes – small bean-shaped organs where particles are removed from lymphThymus – located just above heart – releases WBC’s to travel to other areasSpleen – largest lymph organ – upper left side of abdomen – filters blood and releases WBC’sTonsils – located in back of nasal cavity and back of tongue defend against infectionDiseases include – swelling of lymph nodes, Lymphomas – cancer of the lymphatic system, enlarged spleen and tonsillitis.

Causes of Diseases

Noninfectious Diseases – can’t be spread from one person to another – cancer, heart disease etc.

Infectious Diseases – can be passed from one person to another – cold, flu etc.

Pathogens – bacteria or viruses that cause diseases

Causes of Diseases

How are they passed? Through the air – sneezing, coughing Contaminated objects – things sick people

touch Person to person contact – when you touch a

person with the disease Animals – that bite or sting Food and water – contains pathogens

Defending Against Diseases

How do we counter these problems? Pasteurization – heating milk to kill bacteria Vaccines – shots containing dead

bacteria/viruses so the body can identify them when live ones enter the body

Antibiotics – kill pathogenic bacteria


Macrophage – engulf and eat pathogens

T-Cells – coordinate the immune system

B-Cells – make antibodies

Antibodies – attach to the pathogen and help with the destruction


Steps to kill pathogens Macrophage shows pieces of pathogens to other

cells Antigens who have seen the pathogen activate

the T-Cells T-Cells divide to create Helper T-cells Helper T-cells find a killer T-cell – the Killer

T-cells start to identify and kill infected cells


Helper T-Cells now activate B-Cells B-Cells make antibodies that cling to the

pathogen and act as markers. When the markers are seen, immune cells and proteins swarm and attack the pathogen

Proteins and immune cells enter the pathogen and kill it

Macrophages then engulf the pathogens that were tagged and killed

Respiratory System

Respiration is the entire process by which a body obtains and uses oxygen and gets rid of carbon dioxide and water. Oxygen is needed to convert food to energy.

Respiratory System

Parts of the respiratory system Nose – primary passage in and out Pharynx – air, food, and drink pass

through this – splits into two tubes – one to lungs and one to stomach

Larynx – voice box – controls vocal cords which vibrate to produce sound

Trachea – windpipe from larynx to lungs

Bronchi – 2 pipes – one leads to each lung bronchioles – tiny tubes

Lungs – contain air – forms tiny air sacs called alveoli – capillaries get oxygen from alveoli

Diaphragm – muscle that makes you breathe

Alveoli – tiny sacks that hold air

Respiratory System

Disorders of the respiratory systemAsthma – bronchioles constrict and secrete mucusBronchitis – irritation to lining of bronchiolesPneumonia – bacteria or virus inside lungsEmphysema – eroded lung tissue due to smokingLung cancer – growth of extra tissue due to smoking

Excretory Systems

Excretion is the process by which waste products of metabolism and other non-useful materials are eliminated from an organism.Four Systems of Excretion Skin – releases waste in sweat Digestive system – release feces

from the body Lungs – expel carbon dioxide and

water Urinary system – removes waste

Urinary System

Purpose is to excrete waste – removing wastes and excess products from the bodyKidneys – bean shaped – filters harmful substances from the blood Nephrons – microscopic filters

that remove the waste from blood

Ureter – carries urine from each kidney to the bladderBladder – holds urine for the bodyUrethra – carries urine to the outside of body

Urinary System

Antidiuretic Hormones – hormone that tells kidneys to take back water from nephrons and return to bloodstream – making less urine. Hormones – chemicals that

control actions somewhere else in the body

Diuretic Foods – caffeine is one type that makes more urine

Urinary System

Bacterial Infections – very painful and needs to be treated to prevent death of kidneys

Kidney stones – salt and waste collects inside kidneys and forms small mass which is painful to release

Kidney disease – when kidneys don’t function properly and blood is filtered through a machine



Nervous System

A complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body.

Neuron Structure Cell body – contains nucleus and

organelles Dendrites – branched extensions that

receives messages Axon – fiber that transports

information Axon terminal – tip of axon that

connects to dendrite

Nervous System

Three types of Neurons Sensory – gathers info and sends to central

nervous system; smell, taste, touch, vision, and hearing

Motor neurons – receive impulses from brain or spinal cord to cause muscles to react

Interneurons – interpret and relay information from sensory neurons to motor neurons; found in brain and spinal cord

Nervous System

Two Main Divisions

Central Nervous System – brain and spinal cord

Peripheral Nervous System – consists of the nerves other than the brain and spinal cord.

Nervous System

Central Nervous System Brain – largest organ in system –

controls voluntary and involuntary actions – contains 3 parts

Cerebrum – largest part – dome shaped part where you think and where most memories are stored – controls voluntary movement

Cerebellum – second largest part – receives sensory impulses from muscles and joints – keeps track of body position

Medulla – connects brain to spinal cord – controls involuntary actions

Nervous System

Spinal Cord - contains neurons and axon bundles from the brain – surrounded by vertebrae for protection. Enables brain to communicate with peripheral nervous systemInjury to spinal cord causes paralysis – inability to send messages to lower bodyReflex actions – a quick involuntary action to prevent injury to a body part

Responding to the Environment

Sensations – when electrical signals are sent to the brain for interpretationTypes of sensations Vision – awareness of light

energy Eye contains

Pupil – adjusts light Retina – light sensitive layer

in back of eye Rods – dim light Cones – sees color Iris – color part of eye Lens – changes direction of

light in eye to adjust focus


To hear, object vibrates which pushes on the surrounding air until it reaches the earParts of the ear Outer ear – part you see –

funnels sound Middle ear – eardrum moves

tiny bones Hammer, anvil, stirrup Cochlea – snail shaped

bone that converts waves to electrical impulses

Inner ear – sends impulses to brain


Taste is the awareness of certain dissolved chemicalsTaste buds – receptors for tastePapillae – tiny bumps on tongue that contain taste budsTaste is closely related to smellOlfactory cells – in upper nasal passage, react to chemicals inhaled


The nose has two holes called nostrils. The nostrils and the nasal passages are separated by a wall called the septum Closer to the tip of your nose, the septum is made of cartilage which is flexible material that's firmer than skin or muscle. Behind your nose, in the middle of your face, is a space called the nasal cavity. It connects with the back of the throat. The nasal cavity is separated from the inside of your mouth by the palate (roof of your mouth).


Your nose is more than a passageway for air. The nose also warms, moistens, and filters the air before it goes to the lungs.The mucus membrane (mucus and hairs in your nose) captures dust, germs, and other small particles that could irritate your lungs. Up on the roof of the nasal cavity (the space behind your nose) is the olfactory epithelium which contains special receptors that are sensitive to odor molecules that travel through the air.


There are hundreds of different odor receptors, each with the ability to sense certain odor molecules.

When the smell receptors are stimulated, signals travel along the olfactory nerve to the olfactory bulb. This send the information brain to be interpreted as a smell you may recognize.



Endocrine System

Controls long-term processes – fluid balance, growth, and sexual development

Major organs

Glands – groups of cells that make hormones Hormones – chemicals that control actions somewhere

else in the body Epinephrine or adrenalin – speed up heartbeat and

breathing

Endocrine System

Pituitary gland – secrets hormones that affect other glandsAdrenal gland – responds to stress and dangerPancreas – regulates blood sugar by producing insulinThyroid – increases the rate at which you use energyParathyroid – regulates calciumThymus – regulates immune systemOvaries – females – produces estrogenTestes – males – produces testosterone

Reproductive System

Produces gametes used in fertilization Sexual Reproduction requires two parents

Male Reproductive system Testes – produces the male gamete (sex cell)

called sperm.

Female Reproductive System Ovaries – produces the female gamete called

the egg/ovum.

Male Reproductive System

Female Reproductive System

Reproductive System

Fertilization – ovum (haploid) and sperm (haploid) fuse together to create a new diploid cell called the zygote.

Pregnancy - the zygote begins many cycles of mitosis, and the zygote implants in the female uterus.

As many new cells are created from this zygote, the growing number of cells begin to specialize to from an embryo.

Reproductive SystemEmbryo

FetusNew Born

Human Life Stages

Fertilization – zygote forms

Embryo – fertilized egg that has attached to the wall of the uterus

Fetus – developing baby after the first two month of pregnancy

Birth – baby emerges from mother

Infancy – (first 18 months) period of rapid learning and growth

Childhood – after infancy to age 12 or sexual maturity

Adolescence – age 12 to age 18; final growth spurt occurs

Adulthood – growth of skeletal and muscular systems stops

Older Adulthood – over the age of 60; decline of body systems

Death – physical life ceases

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The Human Body 7 th Grade Life Science Schley County Middle School Coach Blocker.

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