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Anatomy is the study of the structure of an organism

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Title: Anatomy is the study of the structure of an organism


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 animals 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
LE 40-3
Mouth
Gastrovascular cavity
Diffusion
Diffusion
Diffusion
Two cell layers
Single cell
5
LE 40-4
External environment
CO2
O2
Food
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
Circulatory system
10 µm
Nutrients
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).
Inside a kidney is a mass of microscopic tubules
that exchange chemicals with blood flowing
through a web of tiny vessels called capillaries
(SEM).
Anus
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
    animals 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
LE 40-7
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
Cellular respiration
Carbon skeletons
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 animals 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 animals 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
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 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
LE 40-12
40
River otter (endotherm)
30
Body temperature (C)
20
Largemouth bass (ectotherm)
10
0
10
20
30
40
Ambient (environmental) temperature (C)
28
  • Endothermy is more energetically expensive than
    ectothermy
  • Endothermy buffers the animals 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
LE 40-15
Canada goose
Pacific bottlenose dolphin
Blood flow
Vein
Artery
Vein
Artery
33
35C
27
30
20
18
9
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
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 3638C
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 mech
anisms.
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 Bodys 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
animals 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
LE 45-2a
Pathway
Example
Low blood glucose
Stimulus
Receptor protein
Pancreas secretes glucagon ( )
Endocrine cell
Blood vessel
Target effectors
Liver
Glycogen breakdown, glucose release into blood
Response
Simple endocrine pathway
45
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
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
Milk production
Response
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
LE 45-3
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
NUCLEUS
Nuclear response
Synthesis of specific proteins
NUCLEUS
Receptor in plasma membrane
Receptor in cell nucleus
51
  • 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 bodys response to short-term stress

53
LE 45-4
Different receptors
different cell responses
Epinephrine
Epinephrine
Epinephrine
? receptor
? receptor
a 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
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
Oxytocin
HORMONE
ADH
Mammary glands, uterine muscles
Kidney tubules
TARGET
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
  • 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
LE 45-12
Body cells take up more glucose.
Insulin
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)
STIMULUS Dropping blood glucose level (for
instance, after skipping a meal)
Blood glucose level rises to set point stimulus
for glucagon release diminishes.
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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