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Trauma Care! Anatomy is the study of the structure of an organism

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1 Trauma Care! Anatomy is the study of the structure of an organism
Physiology is the study of the functions an organism performs

2 Physical laws and the environment constrain animal size and shape
Physical laws and the need to exchange materials with the environment place limits on the range of animal forms

3 Exchange with the Environment
An animal’s size and shape directly affect how it exchanges energy and materials with its surroundings Exchange occurs as substances dissolved in the aqueous medium diffuse and are transported across the cells’ plasma membranes

4 Mouth Gastrovascular cavity Diffusion Diffusion Diffusion Single cell
Two cell layers

5 LE 40-4 External environment CO2 Food O2 Mouth Animal body Respiratory
system Blood 50 µm 0.5 cm A microscopic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment (SEM). Cells Heart Nutrients Circulatory system 10 µm Digestive system Interstitial fluid Excretory system The lining of the small intestine, a digestive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption (cross-section, SEM). Anus Inside a kidney is a mass of microscopic tubules that exchange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM). Unabsorbed matter (feces) Metabolic waste products (urine)

6 Animal form and function are correlated at all levels of organization
Most animals are composed of specialized cells organized into tissues that have different functions Tissues make up organs, which together make up organ systems

7 Tissue Structure & Function
Different tissues have different structures that are suited to their functions Tissues are classified into four main categories: epithelial, connective, muscle, and nervous

8 Epithelial Tissue Epithelial tissue covers the outside of the body and lines the organs and cavities within the body It contains cells that are closely joined

9 Connective Tissue Connective tissue mainly binds and supports other tissues It contains sparsely packed cells scattered throughout an extracellular matrix

10 Muscle Tissue Muscle tissue consists of long cells called muscle fibers, which contract in response to nerve signals It is divided in the vertebrate body into three types: skeletal, cardiac, and smooth

11 Nervous Tissue Nervous tissue senses stimuli and transmits signals throughout the animal

12 Organ Systems

13 Bioenergetics Bioenergetics, the flow of energy through an animal, limits behavior, growth, and reproduction It determines how much food an animal needs Studying bioenergetics tells us much about an animal’s adaptations

14 Energy Sources and Allocation
Animals harvest chemical energy from food Energy-containing molecules from food are usually used to make ATP, which powers cellular work After the needs of staying alive are met, remaining food molecules can be used in biosynthesis

15 Organic molecules in food External environment Animal body
Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells Energy lost in urine Carbon skeletons Cellular respiration Heat ATP Biosynthesis: growth, storage, and reproduction Cellular work Heat Heat

16 Quantifying Energy Use
Metabolic rate is the amount of energy an animal uses in a unit of time One way to measure it is to determine the amount of oxygen consumed or carbon dioxide produced

17 Thermoregulation Chapter 40

18 Bioenergetic Strategies
An animal’s metabolic rate is closely related to its bioenergetic strategy Birds and mammals are mainly endothermic: Their bodies are warmed mostly by metabolic heat. Endotherms typically have higher metabolic rates

19 Amphibians and reptiles other than birds are ectothermic: They gain their heat mostly from external sources Ectotherms generally have lower metabolic rates

20 Animals regulate their internal environment within relatively narrow limits
The internal environment of vertebrates is called the interstitial fluid and is very different from the external environment Homeostasis is a balance between external changes and the animal’s internal control mechanisms that oppose the changes

21 Regulating and Conforming
Regulating and conforming are two extremes in how animals cope with environmental fluctuations A regulator uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation A conformer allows its internal condition to vary with certain external changes

22 Homeostasis: A dynamic state of stability
Thermoregulation: Maintaining body temperature within certain boundaries, even when surrounding temperature is very different. Homeostasis: A dynamic state of stability between an animal's internal environment and its external environment

23 Thermoregulators Thermoconformers keep core body temperature
within certain limits Thermoconformers change body temperature with the temperature outside of its body

24 Mechanisms of Homeostasis
Mechanisms of homeostasis moderate changes in the internal environment A homeostatic control system has three functional components: receptor control center effector

25 Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off In positive feedback, a change in a variable triggers mechanisms that amplify rather than reverse the change

26 Ectotherms and Endotherms
Ectotherms include most invertebrates, fishes, amphibians, and non-bird reptiles Endotherms include birds and mammals In general, ectotherms tolerate greater variation in internal temperature than endotherms

27 River otter (endotherm)
LE 40-12 40 River otter (endotherm) 30 Body temperature (°C) 20 Largemouth bass (ectotherm) 10 10 20 30 40 Ambient (environmental) temperature (°C)

28 Endothermy is more energetically expensive than ectothermy
Endothermy buffers the animal’s internal temperatures against external fluctuations Endothermy also enables the animal to maintain a high level of aerobic metabolism

29 LE 40-13 Radiation Evaporation Convection Conduction

30 Insulation Insulation is a major thermoregulatory adaptation in mammals and birds Insulation reduces heat flow between an animal and its environment Examples are skin, feathers, fur, and blubber In mammals, the integumentary system acts as insulating material

31 Circulatory Adaptations
Many endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skin In vasodilation, blood flow in the skin increases, facilitating heat loss In vasoconstriction, blood flow in the skin decreases, lowering heat loss

32 Many marine mammals and birds have an arrangement of blood vessels called a countercurrent heat exchanger Countercurrent heat exchangers are important for reducing heat loss

33 Canada goose Pacific bottlenose dolphin Blood flow Artery Vein Vein
33° 30° 27° 20° 18° 10°

34 Adjusting Metabolic Heat Production
Some animals can regulate body temperature by adjusting their rate of metabolic heat production Many species of flying insects use shivering to warm up before taking flight

35 Feedback Mechanisms in Thermoregulation
Mammals regulate body temperature by negative feedback involving several organ systems In humans, the hypothalamus (a part of the brain) contains nerve cells that function as a thermostat

36 Internal body temperature
LE 40-21 Thermostat in hypothalamus activates cooling mechanisms. Sweat glands secrete sweat that evaporates, cooling the body. Blood vessels in skin dilate: capillaries fill with warm blood; heat radiates from skin surface. Increased body temperature (such as when exercising or in hot surroundings) Body temperature decreases; thermostat shuts off cooling mechanisms. Homeostasis: Internal body temperature of approximately 36–38°C Body temperature increases; thermostat shuts off warming mechanisms. Decreased body temperature (such as when in cold surroundings) Blood vessels in skin constrict, diverting blood from skin to deeper tissues and reducing heat loss from skin surface. Thermostat in hypothalamus activates warming mechanisms. Skeletal muscles rapidly contract, causing shivering, which generates heat.

37 Torpor and Energy Conservation
Torpor is a physiological state in which activity is low and metabolism decreases Torpor enables animals to save energy while avoiding difficult and dangerous conditions Hibernation is long-term torpor that is an adaptation to winter cold and food scarcity

38 Estivation, or summer torpor, enables animals to survive long periods of high temperatures and scarce water supplies Daily torpor is exhibited by many small mammals and birds and seems adapted to feeding patterns

39 Endocrine Chapter 45

40 Overview: The Body’s Long-Distance Regulators
Animal hormones are chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body Hormones reach all parts of the body, but only target cells are equipped to respond

41 The endocrine system and the nervous system act individually and together in regulating an animal’s physiology Animals have two systems of internal communication and regulation: the nervous system and the endocrine system

42 The nervous system conveys high-speed electrical signals along specialized cells called neurons
The endocrine system secretes hormones that coordinate slower but longer-acting responses

43 Control Pathways and Feedback Loops
There are three types of hormonal control pathways: simple endocrine, simple neurohormone, and simple neuroendocrine A common feature is a feedback loop connecting the response to the initial stimulus Negative feedback regulates many hormonal pathways involved in homeostasis

44 Simple endocrine pathway
LE 45-2a Pathway Example Low blood glucose Stimulus Receptor protein Pancreas secretes glucagon ( ) Endocrine cell Blood vessel Target effectors Liver Response Glycogen breakdown, glucose release into blood Simple endocrine pathway

45 Pathway Example Stimulus Suckling Sensory neuron Hypothalamus/
LE 45-2b Pathway Example Stimulus Suckling Sensory neuron Hypothalamus/ posterior pituitary Neurosecretory cell Posterior pituitary secretes oxytocin ( ) Blood vessel Target effectors Smooth muscle in breast Response Milk release Simple neurohormone pathway

46 Simple neuroendocrine pathway
LE 45-2c Pathway Example Stimulus Hypothalamic neurohormone released in response to neural and hormonal signals Sensory neuron Hypothalamus Neurosecretory cell Hypothalamus secretes prolactin- releasing hormone ( ) Blood vessel Anterior pituitary secretes prolactin ( ) Endocrine cell Blood vessel Target effectors Mammary glands Response Milk production Simple neuroendocrine pathway

47 Hormones and other chemical signals bind to target cell receptors, initiating pathways that culminate in specific cell responses Hormones convey information via the bloodstream to target cells throughout the body Three major classes of molecules function as hormones in vertebrates: Proteins and peptides Amines derived from amino acids Steroids

48 Signaling by any of these hormones involves three key events:
Reception Signal transduction Response

49 Cell-Surface Receptors for Water-Soluble Hormones
The receptors for most water-soluble hormones are embedded in the plasma membrane, projecting outward from the cell surface

50 Receptor in plasma membrane Receptor in cell nucleus
SECRETORY CELL SECRETORY CELL Hormone molecule Hormone molecule VIA BLOOD VIA BLOOD Signal receptor TARGET CELL TARGET CELL Signal transduction pathway Signal receptor OR Cytoplasmic response DNA Signal transduction and response mRNA DNA Nuclear response NUCLEUS Synthesis of specific proteins NUCLEUS Receptor in plasma membrane Receptor in cell nucleus

51 The same hormone may have different effects on target cells that have
Binding of a hormone to its receptor initiates a signal transduction pathway leading to responses in the cytoplasm or a change in gene expression The same hormone may have different effects on target cells that have Different receptors for the hormone Different signal transduction pathways Different proteins for carrying out the response

52 The hormone epinephrine has multiple effects in mediating the body’s response to short-term stress

53 different cell responses
LE 45-4 Different receptors different cell responses Epinephrine Epinephrine Epinephrine a receptor  receptor  receptor Glycogen deposits Vessel dilates Glycogen breaks down and glucose is released from cell Vessel constricts Intestinal blood vessel Skeletal muscle blood vessel Liver cell Different intracellular proteins different cell responses

54 Intracellular Receptors for Lipid-Soluble Hormones
Steroids, thyroid hormones, and the hormonal form of vitamin D enter target cells and bind to protein receptors in the cytoplasm or nucleus Protein-receptor complexes then act as transcription factors in the nucleus, regulating transcription of specific genes

55 Paracrine Signaling by Local Regulators
In paracrine signaling, nonhormonal chemical signals called local regulators elicit responses in nearby target cells Types of local regulators: Neurotransmitters Cytokines and growth factors Nitric oxide Prostaglandins

56 Prostaglandins help regulate aggregation of platelets, an early step in formation of blood clots

57 The hypothalamus and pituitary integrate many functions of the vertebrate endocrine system
The hypothalamus and the pituitary gland control much of the endocrine system

58 Endocrine Glands

59 Endocrine Glands

60 Hypothalamus Pineal gland Pituitary gland Thyroid gland
LE 45-6 Hypothalamus Pineal gland Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Pancreas Ovary (female) Testis (male)

61 Relation Between the Hypothalamus and Pituitary Gland
The hypothalamus, a region of the lower brain, contains neurosecretory cells The posterior pituitary, or neurohypophysis, is an extension of the hypothalamus Hormonal secretions from neurosecretory cells are stored in or regulate the pituitary gland

62 LE 45-7 Hypothalamus Neurosecretory cells of the hypothalamus Axon
Posterior pituitary Anterior pituitary HORMONE ADH Oxytocin TARGET Kidney tubules Mammary glands, uterine muscles

63 Posterior Pituitary Hormones
The two hormones released from the posterior pituitary act directly on nonendocrine tissues Oxytocin induces uterine contractions and milk ejection Antidiuretic hormone (ADH) enhances water reabsorption in the kidneys

64 Anterior Pituitary Hormones
The anterior pituitary produces both tropic and nontropic hormones

65 Tropic Hormones The four strictly tropic hormones are
Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Each tropic hormone acts on its target endocrine tissue to stimulate release of hormone(s) with direct metabolic or developmental effects

66 Nontropic Hormones Nontropic hormones produced by the anterior pituitary: Prolactin Melanocyte-stimulating hormone (MSH) -endorphin

67 Nontropic Hormones Prolactin stimulates lactation in mammals but has diverse effects in different vertebrates MSH influences skin pigmentation in some vertebrates and fat metabolism in mammals Endorphins inhibit pain

68 Growth Hormone Growth hormone (GH) has tropic and nontropic actions
GH promotes growth directly and has diverse metabolic effects GH stimulates production of growth factors

69 negative feedback loops
The hypothalamus and anterior pituitary control secretion of thyroid hormones through two negative feedback loops

70 Thyroid Hormones 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)

71 Thyroid hormones stimulate metabolism and influence development and maturation
Hyperthyroidism, excessive secretion of thyroid hormones, can cause Graves’ disease in humans

72 The thyroid gland also produces calcitonin, which functions in calcium homeostasis

73 Parathyroid Hormone and Calcitonin: Control of Blood Calcium
Two antagonistic hormones, parathyroid hormone (PTH) and calcitonin, play the major role in calcium (Ca2+) homeostasis in mammals

74 Calcitonin stimulates Ca2+ deposition in bones and secretion by kidneys, lowering blood Ca2+ levels
PTH, secreted by the parathyroid glands, has the opposite effects on the bones and kidneys, and therefore raises Ca2+ levels PTH also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food

75 Insulin and Glucagon: Control of Blood Glucose
The pancreas secretes insulin and glucagon, antagonistic hormones that help maintain glucose homeostasis Glucagon is produced by alpha cells Insulin is produced by beta cells

76 Glucagon Insulin LE 45-12 Body cells take up more glucose.
Beta cells of pancreas release insulin into the blood. Liver takes up glucose and stores it as glycogen. STIMULUS: Rising blood glucose level (for instance, after eating a carbohydrate- rich meal) Blood glucose level declines to set point; stimulus for insulin release diminishes. Homeostasis: Blood glucose level (about 90 mg/100 mL) Blood glucose level rises to set point; stimulus for glucagon release diminishes. STIMULUS: Dropping blood glucose level (for instance, after skipping a meal) Alpha cells of pancreas release glucagon into the blood. Liver breaks down glycogen and releases glucose into the blood. Glucagon

77 Target Tissues for Insulin
Insulin reduces blood glucose levels by Promoting the cellular uptake of glucose Slowing glycogen breakdown in the liver Promoting fat storage

78 Target Tissues for Glucagon
Glucagon increases blood glucose levels by Stimulating conversion of glycogen to glucose in the liver Stimulating breakdown of fat and protein into glucose

79 Diabetes Mellitus Diabetes mellitus is perhaps the best-known endocrine disorder It is caused by a deficiency of insulin or a decreased response to insulin in target tissues It is marked by elevated blood glucose levels

80 Type I diabetes mellitus (insulin-dependent) is an autoimmune disorder in which the immune system destroys pancreatic beta cells Type II diabetes mellitus (non-insulin-dependent) involves insulin deficiency or reduced response of target cells due to change in insulin receptors

81 Adrenal Hormones: Response to Stress
The adrenal glands are adjacent to the kidneys Each adrenal gland actually consists of two glands: the adrenal medulla adrenal cortex

82 Catecholamines from the Adrenal Medulla
The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline) These hormones are members of a class of compounds called catecholamines They are secreted in response to stress-activated impulses from the nervous system They mediate various fight-or-flight responses

83 Stress Hormones from the Adrenal Cortex
Hormones from the adrenal cortex also function in response to stress They fall into three classes of steroid hormones: Glucocorticoids, such as cortisol, influence glucose metabolism and the immune system Mineralocorticoids, such as aldosterone, affect salt and water balance Sex hormones are produced in small amounts

84 Gonadal Sex Hormones The gonads, testes and ovaries, produce most of the sex hormones: androgens Estrogens progestins

85 The testes primarily synthesize androgens, mainly testosterone, which stimulate development and maintenance of the male reproductive system Testosterone causes increase in muscle and bone mass and is often taken as a supplement to cause muscle growth, which carries health risks

86 Estrogens, most importantly estradiol, are responsible for maintenance of the female reproductive system and the development of female secondary sex characteristics In mammals, progestins, which include progesterone, are primarily involved in preparing and maintaining the uterus

87 Melatonin and Biorhythms
The pineal gland, located in the brain, secretes melatonin Light/dark cycles control release of melatonin Primary functions of melatonin appear to relate to biological rhythms associated with reproduction


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