The Human Body Part II
Chapters 37-39
The Respiratory SystemCh. 37-3
Respiration is the process by which oxygen & carbon dioxide are
exchanged between cells, the blood, and air in the lungs
• The Human Respiratory System:– Exchanges oxygen and CO2 between the
blood, air, and tissues
The Respiratory SystemCh. 37-3
• The Respiratory System Consists of:– Nose, Pharynx ,Trachea, Bronchi, Lungs
• How it works: – Air moves from the pharynx into the trachea– Air passes from the trachea into two large passageways called
the bronchi (singular= bronchus)– Each bronchus leads into one of the lungs– Within each lung, the bronchus subdivides into smaller
passageways called the bronchioles– Bronchioles continue to subdivide until they reach tiny air sacs
called alveoli– Oxygen crossed over from the alveolus into thin capillaries and
the blood stream– CO2 crosses over from the blood back into the alveolis to be
disposed of as waste
The Respiratory SystemCh. 37-3
• Generally speaking, the brain controls breathing• The diaphragm, located at the bottom of the chest cavity,
contracts and allows air to rush into the lungs• When the diaphragm relaxes, air is forced back out of
the lungs• The rate of breathing is controlled by the level of CO2 in
the blood • The level of CO2 is measured by the medulla
oblongata in the brain• As CO2 levels rise the medulla oblongata sends nerve
impulses to the diaphragm resulting in the contractions that make us breath in and out.
The Respiratory SystemCh. 37-3
• Tobacco smoke harms the respiratory system• Tobacco smoke contains: nicotine, tar, and
carbon monoxide– Nicotine is a stimulant that increased the heart rate
and blood pressure– Tar contains substances that cause cancer– Carbon monoxide is a poisonous gas that blocks the
transport of oxygen
• Smoking can also cause Emphysema
Food and NutritionCh. 38-1
• The energy to perform actions, as well as the materials from which body cells and tissues are made comes from food
• The energy available in foods can be measured by calories– The # of calories you need each day depends on your
size & level of activity
• Nutrients are substances in food that supply energy and raw materials the body uses for growth, repair, and maintenance
Food and NutritionCh. 38-1
• Carbohydrates are the main source of energy for the body– they include:– Sugars, starches, and fiber
• Fatty acids form fat which is needed to make cell membranes and certain hormones
• Proteins are formed by amino acids and are needed for growth and repair of the body
• Many proteins are also hormones
Food and NutritionCh. 38-1
• Vitamins are organic molecules that help regulate the body
• Minerals are inorganic molecules that perform vital functions in the body– EX: Calcium & iron
Food and NutritionCh. 38-1
• The Food Guide Pyramid can help people select a balanced diet– Classifies food into 6 groups– Foods at base of pyramid should make up
major portion of your diet– Foods at top of pyramid should be consumed
in small amounts
The Process of Digestion Ch. 38-2
• The function of the digestive system is to break down food into simpler molecules that can be absorbed & used by the cell
• Human digestive system includes:– Mouth, pharynx, esophagus, stomach, small
intestine, large intestine, salivary glands, pancreas, and liver
– Digestions starts in the mouth
Food and NutritionCh. 38-1
• The teeth tear & crush food• Salivary glands secrete saliva:
– Amalyse is enzyme found in saliva that breaks chemical bonds between the sugar monomers in starches
– This begins process of chemical digestion
• From the mouth, food passes through the pharynx into the esophagus (passage that carreies food between the pharynx and the stomach)
Food and NutritionCh. 38-1
• Food from the esophagus empties into the stomach
• Glands in the stomach produce an acid and the enzyme pepcin – Stomach churning, along with the acid and
enzyme breaks down food into a soft partially digested mixture called chyme
• Chyme passes into the small intestine (where most chemical digestion and absorption of food occurs)
Food and NutritionCh. 38-1
• Enzymes from the pancreas help digest starch, protein and fat
• A liquid called bile from the liver helps break up fat droplets
• Nutrients are absorbed through the lining of the small intestines– Villi (small fingerlike projections) found in the
small intestines increase the surface are of the small intestines and aide in absorbtion
Food and NutritionCh. 38-1
• Chyme next enters the large intestine where water is removed from digested material
• After most of the water has been removed, remaining waste is passed out of the body
• Digestive Disorders include:– Peptic ulcers= caused by bacteria– Diarrhea= when too little water is removed– Constipation= when too much water is removed
The Excretory SystemCh. 38-3
• The function of the excretory system is to help maintain homeostasis by removing wastes– Wastes like CO2 and urea are produced
during normal metabolism– The main organs of excretory system are
the kidneys:• They remove waste products from blood, maintain
blood pH, and control water content of blood
The Excretory SystemCh. 38-3
• 2 kidneys are located in the lower back:– Blood containing waste enters kidneys– Both useful substances and wastes are removed
from the blood by filtration– Some of the substances are later returned to the
blood– Wastes are excreted– The purified blood leaves the kidneys and returns to
circulation– The fluid that remains is called urine– which contains
urea, excess salts & other substances
The Excretory SystemCh. 38-3
• A tube called the ureter leaves each kidney and carries urine to the bladder (a saclike organ that stores urine)
• Urine passes from the body through a tube called the urethra.
• Kidneys are controlled by hormones and concentration of the blood
• A person can survive with one kidney– If both kidneys fail, a person must undergo dialysis to
survive– Dialysis purifies blood by passing it through a filtering
machine
The Endocrine SystemCh. 39-1
• The endocrine system consists of gland that release hormones into the bloodstream– Hormones are chemicals released from one area of the body
that travel throughout the body to affect cells elsewhere– Hormones bind to chemical receptors on cells called target
receptors
• The endocrine system is made up of glands – A gland is an organ that releases a secretion or hormone– There are endocrine and exocrine glands– Exocrine glands release secretions directly into tissues and
organs• EX: Sweat glands
The Endocrine SystemCh. 39-1
• There are two types of hormones:– Steroid hormones= can cross cell
membranes, enter the nucleus and turn cells on and off
– Nonsteroid hormones= cannot cross cell membranes
• All cells also produce hormonelike substances called prosaglandins that affect only NEARBY cells
The Endocrine SystemCh. 39-1
• The endocrine system is regulated by feedback mechanisms that help maintain homeostasis
• Complementary Hormone Action= 2 hormones with opposite effects may work together to maintain homoestasis– EX: thyroid hormone and thyroid stimulating
hormone
Human Endocrine GlandsCh. 39-2
• Human endocrine glands include:– Pituitary Gland= controls actions of other endocrine
glands– Hpothalamus= Controls pituitary gland– Thyroid Gland= Regulates metabolism– Parathyroid Glands= Regulates calcium levels in
blood– Adrenal Glands= Produce hormones to help deal with
stress– Pancreas= Produces insulin to keep blood sugar
stable– Reproductive Glands= Produce gametes (egg &
sperm)
The Reproductive SystemCh. 39-3
• Sex hormones are produces by gonads of an embryo cause embryo to become either male or female
• Sex hormones cause puberty to occur between ages 9 – 15
• At end of puberty reproductive organs are fully developed and able to function
The Reproductive SystemCh. 39-3
• The male reproductive system produces and delivers sperm
• Main organs of male reproductive system are:– Testes= produce sperm in tiny tubes called
seminiferous tubulues– Scrotum= hold testes– Vas Deferens= first tube sperm travel through– Urethra=Final tube that allows sperm to exit the body
from the penis
The Reproductive SystemCh. 39-3
• The main function of the female reproductive system is to produce eggs and prepare the female body to nourish an embryo
• Main organs of the female reproductive system are:– Ovaries: Produce eggs– Follicles: cluster of cells found in ovaries that
surround egg and help it mature– Fallopian Tube: Egg travels through here where it can
be fertilized if sperm are present– Uterus: Final resting place of egg– Vagina: Connects uterus to the outside of the body
The Reproductive SystemCh. 39-3
• One egg develops each months during the menstrual cycle that is controlled by hormones
• There are 4 phases to the menstrual cycle:– Follicular Phase= egg matures in the follicle and the
uterus is prepared to receive a fertilized egg– Luteal Phase= Follicle turns into structure called
corpus luteum – Fertilization= results in implantation in the uterus
• No fertilization results in menstration– Menstration= the lining of the uterus falls away and
exits the body through the vagina• Will not occur if the egg has been fertilized
Fertilization and DevelopmentCh. 39-4
• Fertilization is the process of a sperm joining an egg
• A fertilized egg is called a zygote• A week after fertilization, a blastocyst (hollow
ball the zygote becomes) implants itself in the lining of the uterus
• The blastocyst differentiates and becomes an embryo
• As the embryo develops, membranes also form to protect and nourish it and help remove waste– EX: Placenta forms and provides nutrients to the
fetus from the mother
Fertilization and DevelopmentCh. 39-4
• After 8 weeks of development the embryo is called a fetus
• By the end of 3 months, most of the major organs are formed
• The last 6 months are used for growth and maturation of fetal organs
• Childbirth results when hormones cause the mother’s uterus to contract
• Contractions push the baby from the mother’s uterus and out through the vagina
Fertilization and DevelopmentCh. 39-4
• Twins are born if more than one egg was fertilized (fraternal twins), or if the zygote splits into two embryos during early development (identical twins)
• Growth and development continue throughout infancy and childhood
• Adolescence begins with puberty and ends with adulthood
• The first signs of aging usually appear in the 30’s