unit 10 the human body

Unit 10 The Human Body

Ch. 37 Circulatory & Respiratory Systems

Functions of the Circulatory System

• The human circulatory system consists of the heart, a series of blood vessels, & the blood that flows through

them

The Heart

• The heart is made almost entirely of muscle, & is a hollow organ about the size of your clenched fist

• Atria - the upper chambers that receive the blood

• Ventricles - the lower chambers that pumps the blood out of the heart

The Heart

• The heart functions as 2 separate pumps• Pulmonary circulation - pathway on the

right side that pumps oxygen-poor blood from the heart to the lungs

The Heart

• Systemic circulation - pathway on the left side

that carries oxygen-rich blood from lungs to the

heart, & the rest of the body

Circulation Through the Heart

• Blood enters the heart through the right & left atria

• It then flows out from the ventricles to either the body or the lungs

• Valves - flaps between the atria & the ventricles, prevent blood from flowing backwards

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Blood Vessels

• Aorta - large blood vessel, carries oxygen-rich blood away from heart to the body

• As blood flows through the circulatory system, it moves through 3 types of blood vessels: arteries, capillaries, & veins

Blood Vessels

• Arteries - vessels that carry blood away from the heart to the tissues of the body– They carry oxygen-rich blood

Blood Vessels

• Capillaries - smallest of the blood vessels• Veins - return oxygen-poor blood to the

heart

Diseases of the Circulatory System

• Cardiovascular diseases, like heart disease & stroke, are among the leading causes of death in the U.S.

• High blood pressure & atherosclerosis are 2 of the main causes of cardiovascular disease


• Atherosclerosis - condition where fatty deposits, called plaque, build up on the inner walls of the arteries– Can cause heart attacks & strokes


• High blood pressure, hypertension, increases the rate of heart attack & stroke

• High blood pressure occurs when deposits of fat build up on the artery walls

Blood & the Lymphatic System

• Blood is a type of connective tissue • It collects oxygen from the lungs, nutrients

from the digestive tract, & waste products from tissues

• Blood helps regulate body temperature• The components that make up blood help

fight infection, & repair damaged blood vessels

Blood Plasma

• The human body has 4-6 liters of blood, or 8% of the total body mass

• 45% of blood consists of cells, that are suspended in the other 55%, plasma

• Plasma - 90% water, 10% dissolved gases, salts, nutrients, enzymes, hormones, waste products, & proteins

Blood Plasma

Blood Cells

• The cellular portion of blood consists of red blood cells, white blood cells, & platelets

Blood Cells

• Red blood cells transport oxygen, are the most numerous, & get their color from hemoglobin– Hemoglobin - iron-containing protein

that binds oxygen in the lungs & transports it to tissues throughout the body where oxygen is released

Blood Cells

• White blood cells are the “army” of the circulatory system - they guard against infection, fight parasites, & attack bacteria– Lymphocytes - a special class of white blood

cells, produce antibodies that are proteins that help destroy pathogens

Blood Cells

• Blood clotting is made possible by plasma proteins

& cell fragments called platelets

• Platelets - large bone marrow cells that have broken into small fragments

The Lymphatic System

• A network of vessels, nodes, & organs called the lymphatic system, collects the fluid that is lost by the blood & returns it back to the circulatory system

• Lymph - fluid collected by the system


• The spleen is an organ whose main function is to destroy damaged red blood cells & platelets

• T cells (white blood cells) mature in the thymus gland, which produces hormones that promote their development

What Is Respiration?

• At the cellular level, respiration takes place in the mitochondria

• It releases energy from the breakdown of food molecules in the presence of oxygen

What Is Respiration?

• At the level of the organism, respiration means the process of gas exchange - the release of carbon dioxide & the uptake of oxygen between the lungs & the environment

The Human Respiratory System

• The basic function of the human respiratory system is to bring about the exchange of oxygen & carbon dioxide between the blood, air, & tissues

• The respiratory system consists of the nose, pharynx, larynx, trachea, bronchi, & lungs


• Pharynx - passageway for both air & food• Larynx - top of trachea, vocal cords• Trachea - windpipe, receives

air from pharynx


• Bronchi - 2 large passageways in the chest cavity, each leads into 1 of the lungs

• Inside the lungs, the bronchi divide into even smaller tubes, called bronchioles

• Alveoli - tiny air sacs at the ends of the bronchioles, where gas exchange takes place

The Respiratory System

Gas Exchange

• There are about 150 million alveoli in each healthy lung

• Oxygen diffuses across the membrane of the alveoli into the capillaries, wrapped around the outside of the alveoli

• At the same time, carbon dioxide diffuses from the blood in the capillaries, into the alveoli, to be excreted

Gas Exchange

Breathing

• Breathing is the movement of air into & out of the lungs

• Diaphragm - large, flat muscle at the bottom of the cavity

Tobacco & the Respiratory System

• The upper part of the respiratory system is able to filter out dust & foreign particles that could damage the lungs

• Smoking tobacco damages that protective layer


• Tobacco contains nicotine, carbon monoxide, & tar

• Nicotine - a stimulant drug that increases heart rate & blood pressure


• Carbon monoxide is a poisonous gas that blocks the transport of oxygen by hemoglobin in the blood

• Tar contains a # of compounds that have been shown to cause cancer


• Smoking reduces life expectancy• Only 30% of male smokers live to age 80,

but 55% of male nonsmokers live to that age

• Smoking can cause respiratory diseases like: chronic bronchitis, emphysema, & lung cancer


• Chronic bronchitis occurs when the bronchi become swollen & clogged with mucus

• Emphysema - the loss of elasticity in the tissues of the lungs, making breathing very difficult


• Lung cancer is deadly because its cells can spread to other locations

• By the time lung cancer is detected, it has spread to dozens of other places


• Smoking is also a major cause of heart disease, it constricts, or narrows, the blood vessels

• There is a drastic change in body temp. & in circulation immediately after smoking a cigarette

unit 10 the human body

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