Unit 12: Animal Structure and Function, Part A

Chapters 40-44

Part A-Structure and Function

• Thermoregulation• Digestive System• Respiratory System

Circulatory SystemImmune System Excretory System Nervous SystemMuscular SystemEndocrine System

Part B-Repro. and Development

• Sexual Characteristics

• Human Reproductive Anatomy

• Gametogenesis

• Hormonal Control of Reproduction

• Embryonic Development

• Factors That Influence Development

Introduction

– Recall that animals are multicellular, heterotrophic eukaryotes that obtain their energy/nutrition by ingesting other organisms. Our focus shifts to understanding why and how animals are so successful in so many habitats.

– Animals are really just a complex system of cells working in a coordinated manner to monitor changing external conditions while maintaining a constant internal environment.

Introduction (cont’d)

– To accomplish these tasks animal cells are organized into systems that are specialized for particular functions. These functions are properties that emerge from the specific shape and order of the given body parts.

– Two major themes are exhibited by animals in this unit:

• capacity to adjust over the long term to the environment by adaptation due to natural selection

• capacity to adjust to the environment over the short term by physiological responses

4 objectives for this introduction:

• identify the hierarchy of structural order in animals

• describe the importance of energetics

• explain how body forms affect interactions with the external environment

• analyze how regulation maintains favorable internal conditions

Levels of Structural Organization

• Cell ---> Tissue ---> Organ ---> Systems

• Tissues: groups of cells w/ common fxn.

• Organs: organized tissues that function together

• Organ systems: several organs with separate functions that act in a coordinated manner

Types of tissues

• epithelial tissue (outer skin layers and internal protective coverings)

• connective tissue (bone, cartilage, blood, adipose, loose and fibrous)

• ** nervous tissue (specialized to conduct an impulse / bioelectric signal)

• ** muscle tissue (consists of long, excitable cells that are contractile)– ** unique to animal kingdom/excitable tissue

Types of epithelial tissues

• top exposed while bottom attached to basement membrane (basal lamina)

• classified by number of cell layers . . . – simple vs. stratified (pseudostratified)

• and the shape of free surface cells– cuboidal– columnar– squamous

Connective tissue fibers

• collagenous

• elastic

• reticular

Major connective tissue types

• loose– fibroblasts– macrophages

• adipose

• Fibrous (tendons and ligaments)

• Cartilage

• Bone

• Blood - consists of liquid (plasma) and cells

Nervous Tissue

• senses stimuli and transmits signals

• neuron - a nerve cell (conducts impulses)– cell body– dendrites: conduct impulses to the cell body– axons: transmit impulses away from cell body

Parts of a Neuron

Types of muscle tissues

• (a) skeletal

• (b) cardiac

• (c) smooth

Types of muscle tissues

Bioenergetics !

• BMR– basal metabolic rate– endotherms

• SMR– standard metabolic rate– ectotherms

Body Plans

Regulation: Internal Environment

• The function of most systems is to contribute toward homeostasis (maintenance of stable, internal conditions within narrow limits). Stable conditions are most often maintained by negative feedback.

Example of Homeostatic Control via Negative Feedback

How does it work?

• A sensing mechanism (receptor) detects a change in conditions beyond specific limits.

• A control center (integrator), often the brain, evaluates the change and activates a second mechanism (effector) to correct the condition.

• In negative feedback, the original condition is canceled, or negated, so that conditions are returned to normal.

What about positive feedback?

• There is also positive feedback, in which an action intensifies/amplifies a condition so that it continues beyond normal limits.

• Examples – three physiological examples in humans…

Thermoregulation (2 groups)

• Ectotherms (poikilotherms)

• Endotherms (homeotherms)

Mechanisms for temp. regulation

• evaporative cooling

• warming via metabolism

• adjusting surface area to regulate temperature– external surfaces– internal surfaces

• countercurrent exchange

Chapter 41: Animal Nutrition

• Nutritional Requirements

• Food Types and Feeding Mechanisms

• Overview of Food Processing

• Mammalian Digestive System

• Adaptations of Vertebrate Digestive Systems

Nutritional Requirements

• animals are heterotrophs - they rely on organic compounds in their food

• an adequate diet provides an animal with:– fuel (chemical energy) for cellular respiration– raw organic materials for biosynthesis– essential nutrients in prefabricated form

Mechanisms of fuel management

– monomers from any of the complex molecules can be used as an energy source, carbos and fats are used first

• oxidized fat produces 9.5 kcal/g= twice as rich in energy than either carbohydrates or proteins

– excess calories are stored in the liver and muscles as glycogen; further excess is stored in adipose tissue as fat

– deficiencies in caloric intake are met by using glycogen stores first, then fat stores, followed by the breakdown of the body’s own proteins.

Diet must supply essential nutrients and carbon skeletons

• biosynthesis involves the processes used to make organic molecules– heterotrophs cannot use inorganic molecules to

make organic ones; they require organic precursors. Examples:

• single types of amino acids supply the necessary nitrogen to build other amino acids

• fats are synthesized from carbohydrates• liver is the most important organ for the conversion of

nutrients from one type of organic molecule to another

Diet (cont’d)

• essential nutrients = chemicals an animal requires but cannot synthesize

• an animal is malnourished if its diet is missing one or more essential nutrients:– essential amino acids: adult humans 12 + 8, infants

11+ 9; kwashiorkor - protein deficiency– essential fatty acids: humans - linoleic acid– vitamins: organic coenzymes (see Table 41.1)– minerals: inorganic nutrients (see Table 41.2)

Vitamins and Minerals

• Vitamins are either water- or fat-soluble– water-soluble are not stored in the body; excesses are

excreted in the urine– fat-soluble can be held in the body; excesses are stored

in body fat; may accumulate to toxic levels and create a condition called vitaminosis

– if an animal synthesizes a certain compound, it is not a vitamin (ascorbic acid: humans/rabbits)

• Minerals may be structural (Ca), part of enzyme (Cu) or other molecules (Fe)

Food Types and Feeding Mechanisms

– Animals usually ingest other organisms; parasites like tapeworms are an exception

• herbivores eat autotrophic organisms• carnivores eat other animals• omnivores eat other animals and autotrophs

– Feeding adaptations• suspension-feeders• substrate-feeders• deposit-feeders• fluid-feeders• bulk-feeders

Overview of Food Processing

• 4 main stages of food processing– ingestion: the act of eating

– digestion: process of breaking down food into particles that are small enough to absorb; hydrolytic enzymes cleave macromolecules into their monomers in special compartments

– absorption: uptake of small molecules from digested material

– elimination: undigested material passes out of the digestive compartment

Specialized Compartments

• intracellular - food vacuoles are simple– organelles which digest food without having to mix

hydrolytic enzymes with cell cytoplasm

• extracellular - compartments are continuous with the outside of the body– gastrovascular cavity - one opening; functions both in

digestion and nutrient distribution– complete digestive tracts, or alimentary canals, run

between two openings; unidirectional flow means that regions of tube can be specialized

Mammalian Digestive System

• consists of an alimentary canal and accessory glands that secrete digestive juices into the canal via ducts– peristalsis - smooth muscles move food– sphincters - ringlike muscle valves occur at

important junctions and regulate movement– accessory glands - 3 pairs of salivary glands,

pancreas, liver, and the gallbladder

Oral cavity and Pharynx

– oral cavity - physical and chemical digestion begin here

• chewing breaks food into smaller pieces to make it easier to swallow and to increase the surface area available to enzymes

• salivary glands are stimulated by the presence of food to secrete saliva; contains mucin, buffers, antibacterial agents, and salivary amylase

– pharynx - intersection for both the digestive and respiratory systems; movement of epiglottis blocks the glottis (windpipe) during swallowing

Esophagus

• muscular tube connects stomach to pharynx

• movement of bolus due to peristalsis

• initial entrance is voluntary (swallowing); once in movement is due to involuntary contraction of smooth muscle

• amylase remains active as the bolus moves through the esophagus

Stomach - (3 fxns.)

• Food Storage - up to 2L

• Churning - mixing of food with secretions– mixture is called acid chyme; passage into

small intestine is controlled by pyloric sphincter

• Secretion - controlled by parasympathetic nerve impulses and hormone - gastrin

3 types of secretory gastric cells

• mucous cells– release mucin and gastrin into bloodstream which

stimulates further gastric secretions

• chief cells– releases pepsinogen - the precursor to pepsin, a

major proteolytic enzyme– releases zymogens - inactive proteases

• parietal cells– secrete HCl - lowers stomach pH to 1-4

Small intestine - (2 fxns.)

• digestion - hydrolytic enzymes and other secretions from 4 organs play a role– pancreas, liver, gallbladder, and the small intestine itself– most enzymatic activity occurs in the duodenum - the

first 25 cm of the small int.

• absorption of nutrients - through villi– villi and microvilli increase the absorptive surface area

of the digestive tract (~300 m2)– occurs in the jejunum and ileum

Pancreas - a compound gland

• endocrine, ductless gland - secretes insulin and glucagon hormones into the blood; not a digestive role

• exocrine, ducted gland - secretes hydrolytic enzymes into the duodenum - break down all major classes of macromolecules; also secretes bicarbonate buffer to neutralize acid chyme

Liver - organ of many functions

• for digestion, the liver produces bile, which:– is stored in the gallbladder– contains no digestive enzymes– contains bile salts which emulsify fats– contains pigments - the byproduct of broken RBCs

in the bloodstream

• emulsification - chemical reaction that converts fat globules into tiny fatty droplets and increases the enzymatic surface area

Major digestive enzymes in SI

• carbohydrates - disaccharidases

• proteins - zymogens are activated by enteropeptidase; converts trypsinogen to trypsin; trypsin activates more enzymes

• nucleic acids - nucleases, nucleotidases

• fats - emulsification; then acted on by pancreatic lipase

Absorption of monomers

• nutrients are either diffused or actively transported across the epithelium and into capillaries– amino acids, sugars, and nucleotides diffuse easily

into the bloodstream– glycerol and fatty acids are recombined in the

epithelial cells to form fats

• capillaries and veins drain nutrients from villi directly into the hepatic portal vein

Regulation of Digestion: Four Regulatory Hormones

– gastrin: released from stomach as a response to the presence of food; stimulates the stomach to release gastric juices (pepsin and HCl)

– secretin: released from duodenum; response to acid chyme entering from the stomach; signals the pancreas to release bicarbonate buffer

– cholecystokinin (CCK): signals the gall bladder to release bile; pancreas to release enzymes

– enterogastrone: response to the presence of fat in the chyme; inhibits peristalsis - slows digestion

Large intestine or Colon

• connects to small intestine in a T junction– blind end of T is the cecum and ends with the

fingerlike extension called the appendix– colon is shaped like an inverted U

• ascending colon, transverse colon, descending colon

• water reclamation is the large intestines major role

• produces feces which are stored in the rectum and passed from the body

Adaptations of Vertebrate Digestive Systems

• Structural adaptations of digestive systems are often associated with diet– dentition in mammals and nonmammals– length of the digestive system vs. diet

• Symbiotic microorganisms aid nourishment– symbiotic bacteria and protozoa may make cellulase– housed in cecum (horse) cecum and colon (rabbit)

or elaborate structure of ruminants

42: Circulation in Animals

• Primary Function: to pump oxygen and nutrient rich liquids throughout the internal environment

• Types of circulatory systemsopen circulatory systemclosed circulatory system

• Major Organs– Heart

– Arteries/Veins/capillaries

Overview of Circulation

• exchange of materials (nutrients, gases, or wastes) b/t animals and the environment take place across moist cell membranes

• Problem of being 3-dimensional– some cells are isolated from the environment

• solution: exchange organs coupled with a system for internal transport

• transport systems connect the exchange organs w/ body cells

Why we need circulation

• time of diffusion is proportional to the square of the distance travelled

• ex. Glucose takes 1 second to diffuse 100 micrometers, therefore it will take 100 seconds to travel 1 mm.

• The presence of a circulatory system reduces the distance a substance must diffuse to enter or leave a cell.

• Most crucial for maintaining homeostasis

Invertebrate Circulation• Gastrovascular Cavities

– cnidarian body plan - two cell layers thick and encloses a g.v. cavity; no need for internal transport system b/c the g.v. cavity distributes it

– planarians and flatworms also have g.v.c. - flattened shape reduces distance for diffusion

• Open Circulatory System - hemolymph– hemolymph acts as both the blood and interstitial fluid; bathes

organs while moving through sinuses; ostia - pores in vessels• Found in insects, other arthropods, and mollusks

Closed Cardiovascular Systems

• consists of a heart, blood vessels, and blood

• the vertebrate heart has:– one atrium (or 2 atria), chamber receives blood– one ventricle (or 2), chamber pumps blood out

• arteries - carry blood away from heart

• veins - carry blood to the heart– blood flow: heart ventricle - artery - arteriole - capillary

- venule - vein - heart atrium• Found in annelids, cephalopods, + vertebrates

Vertebrate Circulatory Systems• Examination of vertebrates shows adaptation

• Fish: 2 chambered heart (1 atrium and 1 ventricle)– single circulation: passes through 2 capillary beds

– blood flow: ventricle - gills (capillary beds) - arteries - organs (capillary bed) - veins - atrium

– disadvantage: low blood pressure - 2 beds

• Amphibians and most reptiles: 3 chambered (2 atria and 1 ventricle)

– double circulation: systemic circuit and pulmocutaneous/pulmonary circuit

– blood flow: ventricle - lungs - left atrium - ventricle - organs - right atrium

– disadvantage: mixing of oxy- and deoxy- blood-1 ventricle

Crocodilian, Avian, and Mammalian Hearts

• Campbell - See Fig. 42.3c and 42.5• Has double circulation with complete separation

of oxy- and deoxy- blood – inc. efficiency of oxygen delivery to cells.– located beneath sternum– 2 atria have thin walls - collection chambers– 2 ventricles w/ thick walls - pump blood– 4 valves in heart - stop backflow during systole

• atrioventricular - found b/t atrium and ventricle• semilunar - b/t aorta and left ventricle and pulmonary artery

and right ventricle• heart murmurs - defect in a valve - allows backflow• Heart rate - # of heartbeats per minute

Rhythmic Pumping in Heart

• Pulse - measure of the # of heartbeats / min• Inversely related to size of animal: elephants ~ 25

beats/min.; shrews ~ 600 beats/min.• cardiac cycle (Fig. 42.6) is the complete sequence

of contraction of heart chambers– systole - muscle contracts and pump blood– diastole - muscle relaxes and chamber fills– cardiac output - volume of blood / min that the left

ventricle pumps to systemic circuit• depends on heart rate and stroke volume• avg. stroke volume ~ 75 mL; avg. output ~ 5.25 L / min

Maintenance of Rhythm

• cardiac muscle is myogenic (self-excitable)– contracts without input from nervous system– tempo - controlled by sinoatrial (SA) node

• called the pacemaker; found in rt atrial wall near superior vena cava (Fig. 42.7)

• contains specialized muscle cells• SA node contraction (causes 2 atria to contract in

unison) atrioventricular (AV) node delay of 0.1 seconds bundle of His Purkinje fibers (causes ventricular contraction from bottom up)

– impulses may be recorded on skin by EKG or ECG - electrocardiogram

Factors that influence SA node

• 2 antagonistic sets of nerves – one speeds up - other slows down the SA node

contractions

• hormonal influence of SA node– epinephrine increases heart rate

• body temperature and exercise

Differences in Blood Vessels

– walls of arteries and veins are 3 layers thick• outer - connective tissue w/ elastic fibers to allow stretching

and recoil of vessel

• middle - smooth muscle and elastic fibers

• inner - endothelium of simple squamous epithelium (Fig. 42.8)

– arteries have thicker walls to provide the strength needed to deal with high forces due to pumping; elasticity evens flow

– veins are thinner to accommodate lower pressure and velocity; flow aided by muscles

– Capillaries are made of only endothelial lining, permits the exchange of chemicals with the interstitial fluids

Fluid Dynamics

• blood flow velocity– differences in speed of blood flow occur in

different parts of the circulatory system• 30 cm/sec in aorta; 0.026 cm/sec in capillary

• law of continuity states that fluid velocity is indirectly proportional to the cross-sectional area of the pipe if the volume of fluid constant

• greater total diameter in capillary beds

Blood Pressure

• forces that blood exerts on vessel walls– greater in arteries than in veins; greatest during

ventricular systole• Blood pressure is determined by cardiac output

and degree of peripheral resistance– Peripheral resistance comes from impedance by

arterioles; blood enters the arteries faster than it can leave.

– This means that there is a pressure even during diastole, blood flows into the capillaries continuously.

• In veins, blood pressure is ~ 0. Blood returns to the heart via contraction of the skeletal muscles.

Diffusion across Capillary Walls

• blood flow through capillary beds– regulation of blood distribution in capillaries

• contraction and relaxation of the smooth muscle layer in arteriole walls

• contraction and relaxation of the precapillary sphincters

• example: blood flow in digestive tract

• capillary exchange– wall is a single, “leaky” layer of simple squamous

cells: vesicle, diffusion, bulk flow

Lymphatic System

• returns fluid to blood and aids in defense

• lymph is similar to interstitial fluid

• two drainage locations - near the shoulders

• vessels are valved to prevent backflow

• lymph capillaries absorb fat in the digestive tract and transport it to the circulatory sys.

• lymph nodes are swellings in the system that filter the lymph and attack pathogens

Blood: a Connective Tissue

• Consists of several cell types suspended in a liquid matrix called the plasma (Fig. 42.13)– Avg. human = 4-6L of whole blood

• Plasma (~55% of volume) – mostly water, also contains electrolytes and proteins

• Cellular elements (~45% of volume)– Erythrocytes (RBCs)

– Leukocytes (WBCs) – 5 types: basophils, eosinophils, neutrophils, lymphocytes, and monocytes

– Platelets

Replacement of cellular elements

• Cellular elements must be replaced as they wear out.

• Pluripotent stem cells give rise to the 3 cellular elements – are found in the red marrow of bones like the ribs, vertebrae, sternum and pelvis.

Blood Clotting

• Clots form when platelets clump together to form a temporary plug.

• The platelets release clotting factors that convert inactive fibrinogen to active fibrin.

• Genetic lack of clotting factors may cause hemophilia, a disorder characterized by excessive bleeding due to minor injuries.

• Sometimes individuals with cardiovascular disease, will form a thrombus (blood clot) within the blood vessels.

Cardiovascular Disease

• Leading cause of death in the US and other developed nations (account for > 50%)

• Most are due to heart attack and stroke– Heart attack: death of cardiac muscle resulting from

prolonged blockage of coronary arteries

– Stroke: death of nervous tissue in the brain resulting from blockage of arteries in the brain.

– Thrombus is often associated with these events

• Atherosclerosis – degeneration of arteries

AP Guide to “ER” vocab

• Now you can watch ER and know what Dr. Carter is saying:– example: “Oh $^!+, asystole! Push 10 mikes of

epi, stat! Charge to 20! Clear!! – Translation: “Fudgecicles, there is no pulse!

Inject ten microliters of epinephrine, now please! Charge the defibrillator paddles to 20 millivolts! Stand back so I don’t shock the urine out of you, thanks!!

Gas Exchange in Animals

• Primary Function: to exchange gases with the environment

• Major Organs/Functional Units– Gills– Lungs/alveolus

Overview of Gas Exchange

Gills: Aquatic Adaptations

Tracheal and Lung Systems

Regulation of Breathing

Pressure Gradients and Diffusion

Respiratory Pigments

Deep-Diving Mammals

Excretory System

• Primary Functionfilter nitrogenous wastes from the blood/osmoregulation

• Major OrgansKidney/nephron

Regulating Water Balance

• the absorption and excretion of water and solutes so that proper water balance (osmotic pressure) is maintained

Example - marine fish

• body is hypoosmotic to environment. (fish is less salty than its environment)– water is constantly lost by osmosis– To maintain its internal environment:

• constantly drink

• rarely urinate

• secrete accumulated salts through their gills

Example - fresh water fish

• body is hyperosmotic to environment. (fish is saltier than its environment)– water constantly diffuses into the body– To maintain its internal environment:

• rarely drink

• constantly urinate

• absorb salts through their gills

Excretory mechanisms

• osmoregulation and removal of toxic substances (includes by-products of protein metabolism, such as nitrogenous wastes)– contractile vacuoles– flame cells– nephridia/metanephridia– Malpighian tubules– kidney = collection of nephrons(filtering tubes)

Parts of the Kidney

• cortex

• medulla

• renal pelvis

• Bowman’s capsule - glomerulus

• convoluted tubules - distal, proximal and the Loop of Henle

• collecting duct

How the Kidney Works

• Filtration

• Secretion

• Reabsorption

Hormonal Regulation

• two hormones influence osmoregulation– antidiuretic hormone (ADH)

• Increases the reabsorption of water by the body and increases the concentration of salts in the urine.

• Increases the permeability of collecting duct to water.

– aldosterone• Increases both the reabsorption of water and Na+

• Increases the permeability of the distal convoluted tubule to Na+. Na+ diffuses out of the tubule, water follows passively

Nitrogenous Wastes

Nervous System

• Primary Functionreceive/interpret/send electrical signals over long distances

• Major OrgansNerves/neuronBrainSpinal Cord

Skeleto-muscular System

• Primary Functionsupport/protection/locomotion

• Major OrgansBoneJointsMuscle/sarcomere

Endocrine System

• Primary Functionsend messages through the body by means of hormones/regulation of development and timing of important events

• Major OrgansPituitary GlandAdrenal Gland

Ch. 43: Immune System

• Primary Function– prevent invasion of body by foreign

pathogens/clean-up or upkeep of the body

• Major Organs and Cells– lymph nodes– T cells/ B cells

3 Levels of Defense

• First 2 lines = non-specific, third = specific.

• 1st line– skin: physical barrier covered in acids, oils, etc.– antimicrobial proteins: found in saliva, tears, etc.

(lysozyme-breaks down the cell walls of bacteria– cilia: found in linings of lungs– gastric juice– symbiotic bacteria

2nd Line

– phagocytes: include neutrophils, monocytes (which become macrophages) and NK cells

– complement: 20 proteins that aid defense rxns.– Interferons: secretions that stimulate neighboring

cells to protect against viruses– inflammatory response

• secretion of histamine by basophils

• vasodilation

• phagocytes

• complement

Third Line - Immune Response

Two kinds of immune responses

• cell-mediated response

• humoral response

Three Aids to Immunity

• antibiotics

• vaccines

• passive immunity

Objective Quiz 40-44– Distinguish between positive and negative

feedback mechanisms.– Define and compare the four main stages of food

processing.– Define a cardiac cycle and distinguish between

systole and diastole.– Distinguish between humoral immunity and cell-

mediated immunity.– Distinguish between regulators and conformers.