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Copyright © 2010 Pearson Education, Inc.
Chapter 19
Sex Differences and Athleticism:
Endocrine, Skeletal, and Muscular Systems
Copyright © 2010 Pearson Education, Inc.
19.1 The Endocrine System - Hormones
Endocrine System Internal system to regulate bodily functions
3 Parts of Endocrine system
1.Endocrine glands secrete hormones
2.Hormones are chemical signals
3.Target cells with specific receptors for hormones
Copyright © 2010 Pearson Education, Inc.
19.1 The Endocrine System - Hormones
Two main types of hormones
1.Protein
2.Steroid – lipid hormone made from cholesterol
Two mechanisms by which hormones interact with target cells: They bind to receptors on the cell’s surface
Protein hormones They diffuse across the cell membrane
Steroids
Copyright © 2010 Pearson Education, Inc.
19.1 The Endocrine System
Protein Hormones Proteins cannot cross cell
membrane Bind to receptors on cell
membrane “Signal transduction”
pathway of proteins carries signal inside cell
Changes ACTIVITY of EXISTING cell components Enzymes, ion channels
Figure 19.1
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19.1 The Endocrine System
Steroid Hormones Steroids can cross cell
membrane Bind to DNA to regulate gene
transcription Control production of NEW
proteins such as enzymes and ion
channels
Figure 19.1
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19.1 The Endocrine System - Hormones
Steroid Hormone Example Sex hormones estrogen and testosterone
are responsible for male and female anatomical development.
Figure 19.2
(a) Breast tissue can respond to estrogen.
(b) The larynx responds to testosterone.
Larynxcell
Breastcell
Estrogen
Estrogen
Testosterone
Testosterone
Estrogenreceptor
Testosteronereceptor
Noreceptor
Noreceptor
Proteins involved inlarynx development
Proteins involved inbreast development
mRNA
mRNA
Nucleus
Nucleus
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19.1 The Endocrine System
Figure 19.3
Hypothalamus secretesgonadotropin-releasing hormone (GnRH).
Pituitary gland responds to GnRH bysecreting the pituitarygonodatropins—follicle-stimulatinghormone (FSH) and luteinizing hormone(LH).
Adrenal glands secrete adrenaline,testosterone (masculinizing hormone),and estrogen (feminizing hormone).
Testes respond to FSH and LH bysecreting testosterone, which aidsin sperm production, increasedmuscle mass, and voice deepening.
Pancreas secretes insulinand glucagon to regulateblood glucose levels.
Thymus secretesthymosin, whichstimulates T cells ofthe immune system.
Parathyroids secreteparathyroid hormoneto raise blood calciumlevels.
Thyroid secretes calcitonin tolower blood calcium levels.
Ovaries respond to FSH and LH bysecreting estrogen, which regulatesmenstruation, maturation of egg cellsbreast development, pregnancy, and menopause.
(a) Some examples of endocrineorgans
(b) Endocrine organs involvedin producing sex differences
Endocrine glands = groups of cells or organs that secrete hormones
Copyright © 2010 Pearson Education, Inc.
19.1 The Endocrine System
Hypothalamus regulates body temperature, affects
hunger, thirst, and reproduction GnRH - Gonadotropin-releasing H.
Pituitary secretes a wide variety of
hormones, including Growth Hormone FSH – Follicle Stimulating H. LH – Luteinizing H.
Figure 19.4
GnRH
Bloodflow
Pituitarygland
Hypothalamus
FSH LH
Stimulatessperm
production
Stimulatesegg cell
development
Stimulatestestosteroneproduction
Stimulatesovulation
Copyright © 2010 Pearson Education, Inc.
19.1 The Endocrine System - Endocrine Glands - Adrenal glands
Adrenal Glands Sit on top kidneys Secrete:
Adrenaline Stress hormones – cortisol, corticosterone Small amounts of sex hormones
(testosterone and estrogen)
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19.1 The Endocrine System - Endocrine Glands - Testes
Testes Secrete testosterone
Sperm production Hair thickness and distribution Muscle mass Voice deepening
Sperm production is more efficient at temperatures lower than body temperature Testes in scrotum outside of body cavity
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19.1 The Endocrine System - Ovaries
Ovaries Secrete estrogen & progesterone
Regulates Menstruation Maturation of egg cells Breast development Pregnancy Menopause
Production of eggs cells begins in utero
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19.1 The Endocrine System - Endocrine Glands
Puberty Beginning of sperm production in males and
egg production in females Age 8 to 13 years old for females, Age 9 to 14 years old for males
Differences in athletic performance are due to affects of sex hormones on skeletal and muscle development
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19.1 The Endocrine System
Animation—The Endocrine SystemPLAY
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19.2 The Skeletal System
Skeletal System
Functions: Supports the body Protects internal organs Aids movement Stores minerals
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19.2 The Skeletal System
The Human Skeleton
Composed of 206 bones
Divided into 2 units Axial skeleton
– ribs, spine, skull Appendicular skeleton
– limbs, pelvic and pectoral girdles
Figure 19.5
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19.2 The Skeletal System - The Human Skeleton
Joints in the skeleton allow for a variety of movements.
Figure 19.6
Femur
Pelvicbone
Femur
Atlas
Axis
(a) Ball and socket joint (hip) (b) Hinge joint (knee)
(c) Pivot joint (neck)
Tibia
Fibula
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19.2 The Skeletal System
Bone Structure
Bone is a living, dynamic tissue that varies depending on function.
Compact bone: densely packed, forms the hard, outer shell of bones
Spongy bone: loosely packed, porous, honeycomb-like, interior Marrow – interior of bone,
produces blood cells Bones have blood vessels inside
and along their surface
Figure 19.7
Bloodvessel
Spongybone
Compactbone
Marrow
Cartilage
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19.2 The Skeletal System
Bone Remodeling
Bones act as a reservoir of calcium they can store excess calcium or release it
as needed Osteoblasts – remove calcium from blood
and deposits into bone Osteoclasts – add calcium to blood by
breaking down and reabsorbing bone tissue
Bones are in a continuous process of remodeling
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19.2 The Skeletal System
Endocrine regulation of Calcium
Parathyroid gland releases parathyroid hormone
stimulates osteoclasts Releases calcium to
blood
Figure 19.8
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19.2 The Skeletal System
Endocrine regulation of Calcium
Thyroid gland releases calcitonin
Stimulates osteoblasts Removes calcium from
blood and deposits it in bone
Figure 19.8
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19.2 The Skeletal System
Sex Differences in Bone Structure
Due to timing and length of puberty, on average males have longer limbs than women On average men are 5.9” taller than women Longer limbs = more power in lever action of
limbs
Women have wider pelvis and lower center of gravity = better balance
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19.2 The Skeletal System
Sex Differences in Bone Structure
Figure 19.9
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19.3 The Muscular System
The Muscular System
3 types of muscle in human body:1. Skeletal
2. Cardiac
3. Smooth
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19.3 The Muscular System
Muscle Interactions With Bone
Muscles and tendons interact with bones to cause movement. They usually work in antagonistic pairs.
Figure 19.10
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19.3 The Muscular System
Muscle Structure and Contraction
Muscles is composed of bundles of muscle fibers arranged in parallel. Muscle fibers are cells Inside cells are myofibrils
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19.3 The Muscular System
Muscle Structure and Contraction
Myofibrils contain repeating elements: Sarcomeres – the functional unit of a
muscle Sarcomeres contain interacting actin and
myosin ‘filaments’
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19.3 The Muscular System
Sarcomere Structure and Contraction
Sarcomeres run from Z-disc to Z-disc Actin (thin filaments) attach to Z disc on
both sides Myosin (think filaments) overlap with actin
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19.3 The Muscular System
Figure 19.12
Sliding Filament Model
1.Myosin has heads that act as ratchets2.ATP causes head to move to cocked position3.Head binds to actin and pulls4.Shortens sarcomere
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19.3 The Muscular System
Animation—Contraction of Skeletal MusclePLAY
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Chapter 19 Section 4
Sex Differences That Influence Athleticism
Copyright © 2010 Pearson Education, Inc.
19.4 Sex Differences That Influence Athleticism
Body Fat Differences
On average women have 10% more body fat than men.
Women begin storing fat on hips, thighs, buttocks and torso at puberty.
Men carry most of their fat on their abdomen.
In women, excessive loss of body fat can lead to cessation of menstrual cycle.
Copyright © 2010 Pearson Education, Inc.
19.4 Sex Differences That Influence Athleticism
Cardiovascular Differences
On average, compared to men of similar size, women have: smaller hearts less blood volume Fewer RBC’s per ml blood smaller lungs
Same amount of aerobic effort puts greater strain on woman’s cardiovascular system
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19.4 Sex Differences That Influence Athleticism
Group Differences and Individual Differences
Averages hide the fact that in large groups, there is much variation.
Ranges for males & females overlap a great deal
Figure 19.14Men Women
32
29
3
12
Most menand womenfall in thesame range.
Perc
ent
body f
at
Copyright © 2010 Pearson Education, Inc.
19.4 Sex Differences That Influence Athleticism
Summary Physical activity is important to health
regardless of gender Children who exercise are more likely to
do so as adults Good exercise habits have many benefits
Decreased risk of heart disease, obesity, diabetes, and many cancers
Regular exercise decreases anxiety and depression
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END Chapter 19 Section 4
Sex Differences That Influence Athleticism