• Endothermic animals generate heat by metabolism; birds and mammals are endotherms

• Ectothermic animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and non-avian reptiles

Endothermy and Ectothermy

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings1

Fig. 40-10Radiation Evaporation

Convection Conduction 2

• Digestion is the process of breaking food down into molecules small enough to absorb– In chemical digestion, the process of enzymatic

hydrolysis splits bonds in molecules with the addition of water

• Absorption is uptake of nutrients by body cells• Elimination is the passage of undigested material

out of the digestive compartment

3

Fig. 41-7

Ingestion Digestion Absorption Elimination

Undigestedmaterial

Chemical digestion(enzymatic hydrolysis)

Nutrientmoleculesenter bodycells

Smallmolecules

Mechanicaldigestion

Food

Piecesof food

1 2 3 4

4

Mutualistic Adaptations

• Many herbivores have fermentation chambers, where symbiotic microorganisms digest cellulose

• The most elaborate adaptations for an herbivorous diet have evolved in the animals called ruminants

5

Fig. 41-20

Esophagus

OmasumAbomasum

Intestine

Rumen Reticulum1 2

4 36

Open and Closed Circulatory Systems

• More complex animals have either open or closed circulatory systems

• Both systems have three basic components:– A circulatory fluid (blood or hemolymph)– A set of tubes (blood vessels)– A muscular pump (the heart)

7

Fig. 42-3

Heart

Hemolymph in sinusessurrounding organs

Heart

Interstitialfluid

Small branch vesselsIn each organ

Blood

Dorsal vessel(main heart)

Auxiliary hearts Ventral vessels

(b) A closed circulatory system(a) An open circulatory system

Tubular heart

Pores

8

Overview: Reconnaissance, Recognition, and Response

• Barriers help an animal to defend itself from the many dangerous pathogens it may encounter

• The immune system recognizes foreign bodies and responds with the production of immune cells and proteins

• Two major kinds of defense have evolved: innate immunity and acquired immunity

9

• Innate immunity is present before any exposure to pathogens and is effective from the time of birth

• It involves nonspecific responses to pathogens• Innate immunity consists of external barriers plus

internal cellular and chemical defenses

• Acquired immunity, or adaptive immunity, develops after exposure to agents such as microbes, toxins, or other foreign substances

• It involves a very specific response to pathogens

10

Innate Immunity of Invertebrates• In insects, an exoskeleton made of chitin forms the

first barrier to pathogens• The digestive system is protected by low pH and

lysozyme, an enzyme that digests microbial cell walls

• Hemocytes circulate within hemolymph and carry out phagocytosis, the ingestion and digestion of foreign substances including bacteria

11

Fig. 43-3

Microbes

PHAGOCYTIC CELL

Vacuole

Lysosomecontaining enzymes

12

• T cells bind to antigen fragments presented on a host cell

• These antigen fragments are bound to cell-surface proteins called MHC molecules

• MHC molecules are so named because they are encoded by a family of genes called the major histocompatibility complex

• In infected cells, MHC molecules bind and transport antigen fragments to the cell surface, a process called antigen presentation

13

Acquired immunity defends against infection of body cells and fluids

• Acquired immunity has two branches: the humoral immune response and the cell-mediated immune response

• Humoral immune response involves activation and clonal selection of B cells, resulting in production of secreted antibodies

• Cell-mediated immune response involves activation and clonal selection of cytotoxic T cells

• Helper T cells aid both responses

14

Innate Immune System Evasion by Pathogens• Some pathogens avoid destruction by modifying

their surface to prevent recognition or by resisting breakdown following phagocytosis

• Tuberculosis (TB) is one such disease and kills more than a million people a year

15

Natural Killer Cells• All cells in the body (except red blood cells) have a

class 1 MHC protein on their surface• Cancerous or infected cells no longer express this

protein; natural killer (NK) cells attack these damaged cells

16

Overview: A Balancing Act

• Physiological systems of animals operate in a fluid environment

• Relative concentrations of water and solutes must be maintained within fairly narrow limits

• Osmoregulation regulates solute concentrations and balances the gain and loss of water

17

Fig. 44-2

Selectively permeablemembrane

Net water flow

Hyperosmotic side Hypoosmotic side

Water

Solutes

18

Insulin and Glucagon: Control of Blood Glucose

• Insulin and glucagon are antagonistic hormones that help maintain glucose homeostasis

• The pancreas has clusters of endocrine cells called islets of Langerhans with alpha cells that produce glucagon and beta cells that produce insulin

19

Fig. 45-12-5

Homeostasis:Blood glucose level

(about 90 mg/100 mL)

Glucagon

STIMULUS:Blood glucose level

falls.

Alpha cells of pancreasrelease glucagon.

Liver breaksdown glycogenand releasesglucose.

Blood glucoselevel rises.

STIMULUS:Blood glucose level

rises.

Beta cells ofpancreasrelease insulininto the blood.

Liver takesup glucoseand stores itas glycogen.

Blood glucoselevel declines.

Body cellstake up moreglucose.

Insulin

20

• Oxytocin induces uterine contractions and the release of milk

• Suckling sends a message to the hypothalamus via the nervous system to release oxytocin, which further stimulates the milk glands

• This is an example of positive feedback, where the stimulus leads to an even greater response

• Antidiuretic hormone (ADH) enhances water reabsorption in the kidneys

21

Fig. 45-16

Suckling

Pathway

Stimulus

Hypothalamus/posterior pituitary

Posi

tive

feed

back

Example

Sensoryneuron

Neurosecretorycell

Bloodvessel

Posterior pituitarysecretes oxytocin ( )

Targetcells

Response

Smooth muscle inbreasts

Milk release

+

22

Thyroid Hormone: Control of Metabolism and Development

• The thyroid gland consists of two lobes on the ventral surface of the trachea

• It produces two iodine-containing hormones: triiodothyronine (T3) and thyroxine (T4)

23

• Thyroid hormones stimulate metabolism and influence development and maturation

• Hyperthyroidism, excessive secretion of thyroid hormones, causes high body temperature, weight loss, irritability, and high blood pressure

• Graves’ disease is a form of hyperthyroidism in humans

• Hypothyroidism, low secretion of thyroid hormones, causes weight gain, lethargy, and intolerance to cold

24

Third Trimester

• During the third trimester, the fetus grows and fills the space within the embryonic membranes

• A complex interplay of local regulators and hormones induces and regulates labor, the process by which childbirth occurs

25

Fig. 46-18

Estradiol Oxytocin

fromovaries

Induces oxytocinreceptors on uterus

from fetusand mother’sposterior pituitary

Stimulates uterusto contract

Stimulates placenta to make

Prostaglandins

Stimulate morecontractions

of uterus

Posi

tive

feed

back

+

+

26

Production of Action Potentials

• Voltage-gated Na+ and K+ channels respond to a change in membrane potential

• When a stimulus depolarizes the membrane, Na+ channels open, allowing Na+ to diffuse into the cell

• The movement of Na+ into the cell increases the depolarization and causes even more Na+ channels to open

• A strong stimulus results in a massive change in membrane voltage called an action potential

27

Fig. 48-10-5

KeyNa+

K+

+50Actionpotential

Threshold

0

1

4

51

–50

Resting potential

Mem

bran

e po

tenti

al(m

V)

–100Time

Extracellular fluid

Plasmamembrane

CytosolInactivation loop

Resting state

Sodiumchannel

Potassiumchannel

Depolarization

Rising phase of the action potential Falling phase of the action potential

5 Undershoot

2

3

2

1

3 4

28

Amino Acids

• Two amino acids are known to function as major neurotransmitters in the CNS: gamma-aminobutyric acid (GABA) and glutamate

29

Neuropeptides

• Several neuropeptides, relatively short chains of amino acids, also function as neurotransmitters

• Neuropeptides include substance P and endorphins, which both affect our perception of pain

• Opiates bind to the same receptors as endorphins and can be used as painkillers

30

Acetylcholine

• Acetylcholine is a common neurotransmitter in vertebrates and invertebrates

• In vertebrates it is usually an excitatory transmitter

31

Fig. 48-17EXPERIMENT

RESULTS

Radioactivenaloxone

Drug

Proteinmixture

Proteinstrapped on filter

Measure naloxonebound to proteinson each filter

32

Emotions

• Emotions are generated and experienced by the limbic system and other parts of the brain including the sensory areas

• The limbic system is a ring of structures around the brainstem that includes the amygdala, hippocampus, and parts of the thalamus

• The amygdala is located in the temporal lobe and helps store an emotional experience as an emotional memory

• Modern brain-imaging techniques suggest that consciousness is an emergent property of the brain based on activity in many areas of the cortex

33

Fig. 49-18

ThalamusHypothalamus

Prefrontalcortex

Olfactorybulb

Amygdala Hippocampus

34

Long-Term Potentiation

• In the vertebrate brain, a form of learning called long-term potentiation (LTP) involves an increase in the strength of synaptic transmission

• LTP involves glutamate receptors• If the presynaptic and postsynaptic neurons are

stimulated at the same time, the set of receptors present on the postsynaptic membranes changes

35

Fig. 49-20

(c) Synapse exhibiting LTP

Mg2+

Na+

(a) Synapse prior to long-term potentiation (LTP)

(b) Establishing LTP

NMDA receptor(open)

Glutamate

StoredAMPAreceptor

NMDAreceptor(closed)

Ca2+

1

3

3

2

14

2

36

Migration

• Migration is a regular, long-distance change in location

• Animals can orient themselves using– The position of the sun and their circadian clock, an

internal 24-hour clock that is an integral part of their nervous system

– The position of the North Star– The Earth’s magnetic field

37

Behavioral Rhythms

• Some animal behavior is affected by the animal’s circadian rhythm, a daily cycle of rest and activity

• Behaviors such as migration and reproduction are linked to changing seasons, or a circannual rhythm

• Some behaviors are linked to lunar cycles– For example, courtship in fiddler crabs occurs during

the new and full moon

38

• Unit 7C40 59&64C41 36&37, 93&94, 111&112C42 10&13, C43 2&4/5, 8&9, 28&29, 42/43&56C44 2&7C45 47&52, 72&73, 85&86C46 98&99C48 41&49, 85&86C49 73&74, 80&81C51 19&21

39