21 lecture presentation

THE STRUCTURAL ORGANIZATION OF ANIMALS

• Life is characterized by a hierarchy of organization.

• In animals:

– Individual cells are grouped into tissues

– Tissues combine to form organs

– Organs are organized into organ systems

– Organ systems make up the entire organism

Cellular level:Muscle cell

Figure 21.1-1

Tissue level:Cardiac muscle

Figure 21.1-2

Organ level:Heart

Figure 21.1-3

Organ level:Heart

Organ system level:Circulatory system Organism level: Multiple

organ systemsfunctioning together

Figure 21.1-5

Level Description

The basic unit ofall living organisms

Muscle cell

Example

HIERARCHICAL ORGANIZATION OF ANIMALS

Figure 21.UN01a

Level Description Example

Tissue A collection of similarcells that performa specific function

Cardiac muscle

Figure 21.UN01b

Organ Multiple tissuesforming a structurethat performs a specific function

Figure 21.UN01c

Organsystem

A team of organs thatwork together

Circulatorysystem

Figure 21.UN01d

Organism A living being, whichdepends on thecoordination of allstructural levels forhomeostasis andsurvival Person

Figure 21.UN01e

Tissue

Organ system

Organism

Description

The basic unit ofall living organisms

A collection of similarcells that performa specific function

Multiple tissuesforming a structurethat performs a specific function

A team of organs thatwork together

A living being, whichdepends on the coordinationof all structural levels forhomeostasis and survival

Muscle cell

Example

Cardiac muscle

Circulatory system

Person

Figure 21.UN01

Form Fits Function

• Analyzing a biological structure gives us clues about:

– What it does

– How it works

• Biologists distinguish anatomy from physiology.

– Anatomy is the study of the structure of an organism.

– Physiology is the study of the function of an organism’s structural equipment.

Tissues

• In most multicellular animals, cells are grouped into tissues.

– A tissue is an integrated group of similar cells that perform a specific function.

– Animals have four main categories of tissue.

Epithelial Tissue

• Epithelial tissue, also known as epithelium:

– Covers the surface of the body

– Lines organs and cavities within the body

Some examples of organslined with epithelial tissue:

Stomach

Small intestine

Large intestine

Urinary bladder

Figure 21.3a

Epithelial tissue lining esophagusFigure 21.3b

Epithelial tissue lining small intestineFigure 21.3c

• Cells of epithelial tissues:

– Are bound tightly together

– Form a protective barrier

– Fall off and are continuously renewed

Connective Tissue

• Connective tissues have a sparse population of cells in an extracellular matrix consisting of a web of protein fibers within a uniform foundation that may be liquid, jellylike, or solid.

• The structure of connective tissue is correlated with its function: to bind and support other tissues.

(a) Loose connective tissue(under the skin)

(b) Adipose tissue

(c) Blood

(d) Fibrous connective tissue(forming a tendon)

(e) Cartilage (at the end of a bone)(f) Bone

Matrix

Plasma

Matrix

Collagenfiber

Fatdroplets

White bloodcells

Red bloodcell

Cellnucleus

Collagenfibers

Figure 21.4

• Loose connective tissue:

– Is the most widespread connective tissue

– Binds epithelia to underlying tissues

– Holds organs in place

(a) Loose connective tissue(under the skin)

Collagen fiber

Figure 21.4a

• Adipose tissue:

– Stores fat

– Stockpiles energy

– Pads and insulates the body

(b) Adipose tissue

Fatdroplets

Figure 21.4b

• Blood:

– Is a connective tissue with a matrix of liquid

– Contains red and white blood cells suspended in plasma

(c) Blood

Plasma

White blood cells

Red blood cell

Figure 21.4c

• Fibrous connective tissue:

– Has a dense matrix of collagen

– Forms tendons and ligaments

(d) Fibrous connective tissue(forming a tendon)

Cell nucleus

Collagen fibers

Figure 21.4d

• Cartilage:

– Has a strong but rubbery matrix

– Functions as a flexible, boneless skeleton

– Forms the shock-absorbing pads that cushion the vertebrae of the spinal column

(e) Cartilage (at the end of a bone)

Matrix

Figure 21.4e

• Bone:

– Is a rigid connective tissue

– Has a matrix of collagen fibers hardened with deposits of calcium salts

(f) Bone

Matrix

Figure 21.4f

Muscle Tissue

• Muscle tissue:

– Consists of bundles of long, thin, cylindrical cells called muscle fibers

– Has specialized proteins that contract when stimulated by a nerve

(a) Skeletal muscle(short segments ofseveral muscle fibers)

(b) Cardiac muscle

Unit ofmusclecontraction

Musclefiber(cell)

Musclefiber

Junction betweentwo cells

(c) Smooth muscle

Nucleus

Muscle fiber

Nuclei

Figure 21.5

(a) Skeletal muscle(short segments ofseveral muscle fibers)

Unit ofmusclecontraction

Muscle fiber(cell)

Nuclei

Figure 21.5a

(b) Cardiac muscle

Musclefiber

Junction between two cells

Nucleus

Figure 21.5b

(c) Smooth muscle

Muscle fiber

Nucleus

Figure 21.5c

• Skeletal muscle is:

– Attached to bones by tendons

– Responsible for voluntary movements

– Striated because the contractile apparatus forms a banded pattern in each cell or fiber

• Cardiac muscle is:

– Composed of cells that are branched and striated

– Found only in heart tissue

– Responsible for the contraction of the heart

• Smooth muscle is:

– Named for its lack of obvious striations

– Found in the walls of various organs

– Involuntary

Nervous Tissue

• Nervous tissue:

– Makes communication of sensory information possible

– Is found in the brain and spinal cord

– Consists of a network of neurons

Spinal cord

Figure 21.6a

Signal-receivingextensions Cell body

Signal-transmittingextensions

Figure 21.6b

Organs and Organ Systems

• An organ consists of two or more tissues packaged into one working unit that performs a specific function.

• Examples include the heart, liver, stomach, brain, and lungs.

• Organ systems:

– Are teams of organs that work together

– Perform vital body functions

Blast Animation: Anatomy of the Kidney

Skeletal system:supports body andanchors muscles

Cartilage

Figure 21.8a

Circulatory system:transports substancesthroughout body

Blood vessels

Figure 21.8b

Respiratory system:

exchanges O2 and

CO2 between blood

and air

Nasal cavity

Bronchus

Pharynx

Trachea

Larynx

Figure 21.8c

Digestive system:breaks down foodand absorbsnutrients

Large intestine

Small intestine

Esophagus

Stomach

Figure 21.8e

Muscular system:moves body

Skeletal muscles

Figure 21.8d

Urinary system:rids body ofcertain wastes

Urinary bladder

Urethra

Ureter

Kidney

Figure 21.8f

Reproductive system:produces gametesand offspring

Seminal vesicles

Prostate gland

Vas deferens

Urethra

Oviduct

Vagina

Uterus

Ovary Penis

Testis

Figure 21.8h

Lymphatic andimmune system:defends againstdisease

Lymphaticvessels

Lymphnodes

Thymus

Spleen

Figure 21.8j

Sense organ(ear)

Nervous system:processes sensoryinformationand controlsresponses Spinal cord

Nerves

Figure 21.8k

EXCHANGES WITH THE EXTERNAL ENVIRONMENT

• Every organism is an open system, continuously exchanging chemicals and energy with its surroundings to survive.

• An animal’s size and shape affect how it exchanges energy and materials with its surroundings.

• All living cells must be bathed in a watery solution so that exchange of materials can occur.

• Animals use three organ systems to exchange materials with the external environment:

– Digestive

– Respiratory

– Urinary

• The circulatory system transports materials inside the body from these exchange surfaces.

Unabsorbed matter (feces) Metabolic waste products (such as urine)

External environment

RespiratorysystemDigestive

system

Urinarysystem

Circulatorysystem

Interstitialfluid

Nutrients

Body cells

Animal

Mouth Food

Figure 21.11

REGULATING THE INTERNAL ENVIRONMENT

• Every living organism has the ability to respond to its environment.

Homeostasis

• Homeostasis is the body’s tendency to maintain relatively steady conditions in the internal environment when the external environment changes.

Externalenvironment

Large externalchanges

Animal’s internalenvironment

Homeostaticmechanisms

Small internalchanges

Figure 21.12

Negative and Positive Feedback

• Most mechanisms of homeostasis depend on a common principle called negative feedback, in which the results of a process inhibit that same process, such as a thermostat that turns off a heater when room temperature rises to the set point.

Animation: Positive Feedback

Animation: Negative Feedback

Thermostat(control center)turns heater off

Set point:Room temperature20C (68F)

Roomtemperaturedrops

Response:Heatingstops

Stimulus:Room temperatureis above set point

Figure 21.13a

Thermostat(control center)turns heater on

Set point:Room temperature20C (68F)

Roomtemperaturerises

Response:Heatingstarts

Stimulus:Room temperatureis below set point

Figure 21.13b

• Less common is positive feedback in which the results of a process intensify that same process, such as uterine contractions during childbirth.

• Humans have homeostatic mechanisms that aid in thermoregulation, which:

– Cool or

– Heat the body

Blast Animation: Negative Feedback: Body Temperature

Bodytemperaturedrops

Set point:Body temperature near 37C (98.6F)

Stimulus:Body temperatureis above set point

Control centerin brain activatescooling mechanisms

Response:1. Blood vessels dilate2. Sweat is produced

Sweatgland

Figure 21.14a

Set point:Body temperature near 37C (98.6F)

Bodytemperaturerises

Stimulus:Body temperatureis below set point

Control centerin brain activateswarming mechanisms

Response:1. Blood vessels constrict2. Muscles shiver3. Metabolic rate increases

Figure 21.14b

• Fever:

– Is an abnormally high internal body temperature

– Usually indicates an ongoing fight against infection

Osmoregulation

• Living cells depend on a precise balance of:

– Water

– Solutes

• Osmoregulation is the control of the gain or loss of:

– Water

– Dissolved solutes, such as salt

Homeostasis in the Urinary System

• The urinary system:

– Plays a central role in homeostasis

– Forms and excretes urine

– Regulates the amount of water and solutes in body fluids

• In humans, the two kidneys:

– Are the main processing centers

– Contain many fine tubes called tubules

– Include an intricate network of capillaries

• As blood circulates through the kidneys:

– A fraction of it is filtered

– Plasma enters the kidney tubules, forming filtrate

• Filtrate contains:

– Valuable substances that need to be reclaimed (such as water and glucose)

– Substances to be eliminated, such as urea

• The human urinary system includes:

– The kidneys

– Nephrons, the functional units of the kidney

– The urinary bladder, where urine is stored

Animation: Nephron Introduction

Renal artery (red) andrenal vein (blue)

(a) Urinary system

Kidney

Ureter

Urinarybladder

Urethra

Figure 21.17a

(b) Kidney

Ureter

Nephron

Figure 21.17b

• Nephrons:

– Carry out the functions of the urinary system

– Consist of a tubule and its associated vessels

– Number more than a million in a kidney

(c) A nephron and collecting duct

Branch ofrenal artery

Branch ofrenal vein Collecting

Filter Tubule

To ureter

Figure 21.17c

• Nephrons perform four key functions:

– Filtration, forcing water and other small molecules from the blood to form filtrate

– Reabsorption of water and valuable solutes back into the blood

– Secretion of certain substances, such as ions and drugs, into the filtrate

– Excretion of urine from the kidneys

Filtration Reabsorption Secretion

Renal artery

Renal vein

Capillaries

Tubule

Filtrate

Excretion

Figure 21.18

• Hormonal control of the nephrons allows the body to control its internal concentration of:

– Water

– Dissolved molecules

• Kidney failure can be caused by:

– Injury

– Illness

– Prolonged use of pain relievers, alcohol, or other drugs

• One option for treatment of kidney failure is dialysis, filtration of blood by a machine.

Used dialyzingsolution (withurea andexcess salts)

Line fromapparatusto vein

Fresh dialyzingsolution

Dialyzingsolution

Line from arteryto apparatus

Tubing made of aselectively permeable membrane

Figure 21.19

21 lecture presentation

pearson education

muscle cell tissue level

muscle cell figure

structure of connective

loose connective tissue

widespread connective

rigid connective tissue

cell level description

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