Exam 4

Tissues

groups of similar cells that perform a common function

Types of Tissues

1. Epithelial

2. Connective

3. Muscle

4. Nervous

Epithelial Tissue (Epithelium)

tightly packed sheets of cells that cover organs and outer surfaces, as well as line hollow organs, vessels, and body cavities

• Anchored on one face, but free on another

  • Free side exposed to body fluids or the external environment

• Can be single layer or many layers

  • Constantly sloughing off; replaced by cell division

Functions of Epithelial Tissue (Epithelium)

1. Protection

2. Secretion

3. Absorption

Connective Tissue

loosely organized and composed of cells embedded in a matrix of protein fibers and ground substance

• Usually binds T organs or tissues to one another

Types of Connective Tissue

1. Loose connective tissue

2. Adipose tissue

3. Blood

4. Fibrous connective tissue

5. Cartilage

6. Bone

Loose Connective Tissue

connects epithelia tissues, holds organs in place, pads skin

• Most widespread tissue in animals

Loose Connective Tissue Structure

matrix composed of collagen fibers for strength and elastin fibers for stretching

• “Loose” due to loosely woven fibers

Adipose Tissue

fat tissue

• Connects skin to underlying structures

• Insulates and protects organs

• Makes and stores energy-rich reserves of fat

• Primarily cells; small amount of matrix

Blood

Connective tissue that circulates throughout the body via blood vessels

• Composed of…

  • Liquid Portion/Matrix: plasma

  • Solid Portion: red blood cells, white blood cells, and platelets

Blood Stem Cells

Stem cells in bone marrow produce cellular components of blood

Red Blood Cells

carry oxygen from lungs to body

• Small, pinched shape provides large surface area to volume ratio for rapid oxygen diffusion

• No nucleus or other organelles

How are new red blood cells made?

Body knows when you need more through negative feedback: low blood oxygen levels

• Made in bone marrow

• Stems cells divide to make one new stem cell (replacement) and one new RBC

Hemoglobin

a protein in red blood cells that transports oxygen to the tissues and carbon dioxide to the lungs

• Made of four different protein chains, each with an iron atom that binds with oxygen

White Blood Cells

fight infection/attack invaders

• Remove toxins, wastes, and damaged cells

• Less white blood cells than red blood cells

• Have nuclei

Platelets

work with proteins to clot blood

Fibrous Connective Tissue

forms tendons and ligaments

• Matrix is densely packed collagen fibers running in parallel

Tendons

connect muscles to bones

Ligaments

connect bones to each other at joints

Cartilage

Connects muscles with bones

• Composed of chondrocytes

• Matrix rich in collagen and other structural proteins

• Allow for shock absorption

• Cushions joints

• No blood vessels, so slow to heal

Bone

Rigid connective tissue composed of branched osteocytes

• Matrix composed of collagen and minerals

• Supports and protects other tissues and organs

• Reservoir of calcium and minerals if dietary levels are too low

Muscle Tissue

highly specialized tissue capable of contracting

• Composed of long, thin cylindrical cells called muscle fibers

• Fibers contain specialized proteins, actin and myosin

  • Cause contractions when signaled by nerve cells

Types of Muscle Tissues

1. Skeletal

2. Cardiac

3. Smooth

Skeletal Muscle

usually attached to bone

• Striated

• Voluntary movements

• Exercise increases size of skeletal cells

Cardiac Muscle

found only in heart tissue

• Striated

• Involuntary movements

• Undergoes rhythmic contractions to produce heartbeat

  • Branched, interwoven cells help contraction signal to propagate

Smooth Muscle

• Not striated

• Involuntary movements

• Comprises the musculature of internal organs, blood vessels, and the digestive system

• Contracts more slowly than skeletal muscle but remains contracted longer

Nervous Tissue

Composed of neurons that conduct and transmit electrical impulses

• Found in the brain, spinal cord, and nerves

• Most nerve cells do not undergo cell division to repair damage

Nervous Tissue Functions

1. Senses stimuli

2. Processes stimuli

3. Transmits signals from the brain to the body

Organs

structures composed of two or more tissue types working together for a specific function

Organ Systems

organs that interact to perform a common function

Liver

Found on the right side of the abdomen below the diaphragm

• Divided into four lobes, subdivided into lobules

  • Contain a central vein that allows blood to reach all of the liver

• Hepatocytes filter toxic materials from blood

• Associated with the gallbladder

Organ Systems of the Liver

• Circulatory System

• Digestive System

The Circulatory System and the Liver

1. Synthesize blood-clotting factors

2. Detoxify harmful substances in the blood

3. Regulate blood volume

4. Destroy old red blood cells

The Digestive System and the Liver

1. Produce bile

2. Metabolize and store nutrients

3. Stores and releases excess glucose

Liver Transplants

• usually because liver failure:

  • Hepatitis C

  • Chronic alcohol use

• Liver can come from living or dead donors: small piece of liver can be transplanted and will regenerate in donor and recipient

Organ Failure

failure of one organ can affect one or more systems (liver failure affects circulatory and digestive systems for example)

• Compromises body’s overall ability to maintain a steady state

Homeostasis

The ability to maintain a consistent internal environment under changing conditions

Negative Feedback

the product of the process inhibits the process (reverses a change)

• Controls thermoregulation and blood glucose level regulation

Positive Feedback

the product of the process intensifies the process

• Labor and childbirth: hormones release during childbirth that cause contractions to birth the baby

The Digestive System

Breaks down food to be used for energy by the body

Alimentary Canal

AKA the digestive tract

• Where absorption and elimination occur

Steps of food in the Digestive Tract

1. Ingestion: taking food into the digestive tract

2. Digestion: breaking the food into small units

3. Absorption: bringing the food from the tract into the cells of the body

4. Elimination: expelling the unusable parts of the food from the digestive tract

Absorption Steps

1. Small nutrients are absorbed into the circulatory or lymph systems

2. Nutrients and water diffuse from blood and lymph into the cell

3. Digested nutrients are absorbed into the bloodstream

Villi and Microvilli

Increase the surface area of the small intestine for nutrient absorption

The Small Intestine

Most absorption takes place in small intestine

• Many folds and projections give it the approximate surface area of a tennis court

• Minute projections called villi (singular: villus) cover the entire folded area

• Villi move back and forth in chyme

• Each cell of villi has microscopic projections called microvilli

Elimination

Any material not absorbed move through large intestine/colon and are eliminated through feces

• Feces mainly consists of indigestible plant fibers

Types of Digestion

1. Mechanical digestion

2. Chemical digestion

Mechanical Digestion

grinds down food to increase surface area

Mechanical Digestion Steps

1. Begins in the mouth (oral cavity)

   • Teeth chew and grind food into smaller pieces

   • Tongue forms a bolus (ball of food) and pushes it to the back of the mouth

2. Bolus moves to pharynx and esophagus

3. Peristalsis: smooth muscle contractions push food through esophagus to stomach

Chemical Digestion

secretions help convert polymers into subunits

Chemical Digestion Steps

1. Begins in the mouth

   • Salivary amylase breaks down sugars

2. In the stomach

   • Forms chyme: a slurry with digestive enzymes (gastric juices)

   • Pepsin breaks down proteins

3. In the small intestine

   • Intestinal enzymes and pancreatic enzymes break down all nutrient types

Accessory Organs in the Digestive System

Outside of the alimentary canal but produce or secrete substances for digestion

1. Pancreas

2. Liver

3. Gallbladder

Pancreas in the Digestive System

produces secretions to neutralize stomach acids and enzymes to digest nutrients

Liver in the Digestive System

produces bile to help dissolve fats

Gallbladder in the Digestive System

stores and concentrates bile to be released into the small intestine

Alcohol and the Digestive System

• Alcohol relaxes the muscles for peristalsis: food spends more time in digestive tract = more enzyme exposure = diarrhea

• Food in the stomach slows the rate of alcohol absorption in the small intestine

• Liver metabolizes toxins including alcohol

• Pancreatitis: inflammation of the pancreas prevents secretion of digestive enzymes

The Urinary System

Removes waste while retaining materials to be reused and recycled

• Organs:

  • Kidneys

  • Ureters

  • Urinary bladder

  • Urethra

Kidneys

filter and cleanse circulating blood

• Paired organs located behind the liver and stomach

• Contain nephrons (looped tubules)

• Supplied with blood by the renal arteries

Nephrons

Functional unit of the kidneys (removes toxins and produces urine)

• Process waste in four phases:

1. Filtration

2. Reabsorption

3. Secretion

4. Excretion

Effects of Alcohol on the Urinary System

• Alcohol is a diuretic: Promotes the formation of urine and increases the volume of urine released from the bladder

• Alcohol acts on the pituitary gland to lessen antidiuretic hormone (ADH) secretion: Kidneys reabsorb less water and produce more urine

• Alcohol is a depressant: slows down brain function

Environmental Tobacco Smoke

secondhand smoke emitted by a lit cigarette combined with smoke exhaled by active smokers

What is the most abundant gas in tobacco smoke?

Carbon monoxide

Diaphragm

Dome-shaped muscle

• Separates respiratory system from the digestive organs

Ventilation

Consists of inhalation and exhalation

• Your brain responds to levels of CO₂

• High levels of CO₂ –> increases ventilation

  • Increases the level of O₂

  • Removes the CO₂

Inhalation

1. Diaphragm contracts

2. Air flows in

Exhalation

1. Diaphragm relaxes

2. Air flows out

Lungs

Air enters the lungs through bronchi which branch into bronchioles

Alveoli

Tiny sacs at the end of bronchioles

• Contain the respiratory surface (size of tennis court)

• Supplies O₂ and removes CO₂ waste

• Total amount of respiratory surface can be destroyed by smoke —> shortness of breath and wheezing

Gas Exchange

Process that acquires O₂ from the environment and expels CO₂ from the body

• Necessary for cellular respiration

• Occurs by simple diffusion between the alveoli and surrounding capillaries

• Surfactant covering surfaces may be negatively affected by tobacco smoke

Hemoglobin and Smoking

Hemoglobin binds to carbon monoxide (which comes from smoking) more strongly than to oxygen

• Causes oxygen shortages in tissues

How do lungs expel and remove foreign objects?

1. Coughing: response to large particles in trachea

2. Mucus traps smaller particles

3. Cilia move trapped particles to nose and mouth

4. Mucus is coughed up, expelled from nose or mouth, or swallowed

Effects of particles in tobacco smoke

• Increases mucus production

• Damages cilia in bronchi: more difficult to expel mucus and particles

• Bronchitis: inflammation of bronchi

  • Abundant mucus production

  • Lasting cough

• Asthma: allergic response resulting in muscular constriction of bronchial walls

• Emphysema: lung disease cause by damage to alveoli walls

  • Reduces surface area for gas exchange

  • Permanently damage alveoli

• Lung Cancer

The Cardiovascular System

distributes gases and other materials around the body

• Three main components:

1. Circulating fluid (blood)

2. Pump (heart)

3. Vascular system (blood vessels and capillaries)

Vascular/Circulatory System

blood vessels that carry blood to and from the heart

• Composed of…

  1. Arteries

  2. Capillaries

  3. Veins

Arteries

Move blood away from the heart

• Thick muscular walls

• Ability of these muscles to dilate and constrict aids in the maintenance of blood pressure

  • Constricted arteries = faster flow

  • Relaxed arteries = slower flow

• Arteries —> arterioles —> capillaries

Arterioles

Connect arteries and capillaries

• Very small

Capillary Networks

Designed so materials can move in and out easily

• Located next to every cell in your body

Capillaries

contain thin, porous walls to exchange gases and other materials

• Capillary bed: network of capillaries found in highly used tissues

  • Materials forced out due to higher blood pressure near arterial end of capillary bed

Veins

Carry the oxygen depleted (not always) blood back to the heart

• Blood is under lower pressure than arteries from large diameter and less muscle

• Valves are used to ensure the one way flow of blood

Heart

Consists of two muscular pumps and four chambers

• Right and left atria

• Right and left ventricles

• Right side receives oxygen-poor blood from the body and sends it to the lungs

  • Pulmonary circulation

• Left side receives oxygen-rich blood from the lungs and sends it to the body

  • Systemic circulation

The Circulatory/Vascular System Pathway

1. Right ventricle: Pulmonary semilunar valve

2. Pulmonary arteries: Lungs, Pulmonary veins

3. Left atrium: Left atrio-ventricular valve

4. Left ventricle: Aortic semilunar valve

5. Aorta

6. Right atria

The Heartbeat

• Systole: Atria and ventricles contract, blood is pushed out

• Diastole: Atria and ventricles relax, heart chambers fill

• Sound comes from the closing of the heart valves

How is the heartbeat controlled?

pacemaker cells located in the sinoatrial node in right atrium

• Signals the atria to contract —> pause as impulse moves to the atrioventricular node —> Signals the ventricles to contract

Cardiac Output

The volume of blood per minute that the left ventricle pumps into the systemic circuit

• The amount of blood pumped by the left ventricle each time it contracts times the heart rate

Heart Valves

• Made of flaps of connective tissue

• Prevent backflow: valves close when ventricles contract, keeping blood from flowing back into the artria

Heart Murmur

a stream of blood squirts backward through a valve

High Blood Pressure

hypertension

• Affected by epinephrine and norepinephrine

• Leads to arteriosclerosis (hardening of the arteries)

Blood Clots

result from an increase in the stickiness of platelets and formation of fibrinogen

• Can occur from smoking

• Types:

  • Thrombosis

  • Embolism

Thrombosis

blood clot in blood vessel blocks blood flow

Embolism

blood clot breaks free and becomes lodged in another blood vessel

What do most deaths due to smoking result from?

Cardiovascular disease