Chapter 19

Copyright © 2010 Pearson Education, Inc.

Chapter 19

Sex Differences and Athleticism:

Endocrine, Skeletal, and Muscular Systems


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



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


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



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



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



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



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


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)


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


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


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



Animation—The Endocrine SystemPLAY


19.2 The Skeletal System

Skeletal system

Functions: Supports the body Protects internal organs Aids movement Stores minerals


19.2 The Skeletal System - The Human Skeleton

Human skeleton is composed of 206 bones divided into 2 units Axial skeleton

– ribs, spine, skull Appendicular

skeleton – limbs, pelvic and pectoral girdles

Figure 19.5


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


19.2 The Skeletal System - Bone Structure and Remodeling

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


19.2 The Skeletal System - Bone Structure

Bones act as a reservoir of calcium they can store excess calcium or release it

as needed Osteoblasts – remove calcium from blood

during bone deposition process Osteoclasts – add calcium to blood by

breaking down and reabsorbing bone tissue

Bones are in a continuous process of remodeling



Endocrine regulation of Calcium

Parathyroid gland releases parathyroid hormone

stimulates osteoclasts Releases calcium to

blood

Figure 19.8



Endocrine regulation of Calcium

Thyroid gland releases calcitonin

Stimulates osteoblasts Removes calcium from

blood and deposits it in bone

Figure 19.8


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



Sex Differences in Bone Structure

Figure 19.9


19.3 The Muscular System

The Muscular System

3 types of muscle in human body:1. Skeletal

2. Cardiac

3. Smooth


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



Muscle Structure and Contraction

Muscles is composed of bundles of muscle fibers arranged in parallel. Muscle fibers are cells Inside cells are myofibrils



Muscle Structure and Contraction

Myofibrils contain repeating elements: Sarcomeres – the functional unit of a

muscle Sarcomeres contain interacting actin and

myosin ‘filaments’



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



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



Animation—Contraction of Skeletal MusclePLAY


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.


19.4 Other 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



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



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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Chapter 19