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4U BIO > 9.1/9.2/9.3/9.4 > Flashcards

9.1/9.2/9.3/9.4 Flashcards

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1
Q

Endocrine System

A

System that works in parallel with the nervous system to maintain homeostasis by releasing chemical hormones from various glands.

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2
Q

Endocrine Gland

A

Ductless gland that secretes hormones directly into the bloodstream.
action of hormone can happen far from the endocrine gland secreting the hormone

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3
Q

Hormone

A

Chemical messengers sent to many parts of the body to produce a specific effect on a target cell or organ.

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4
Q

What are hormones responsible for controlling?

A
  • Growth and Development
  • Metabolism
  • Regulation of Internal
    Environment
  • Reproduction
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5
Q

Glands that Function Exclusively as Endocrine Glands

A
  • pituitary
  • pineal
  • thyroid
  • parathyroid
  • adrenal glands
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6
Q

Tissues and Organs that Secrete Hormones

A
  • hypothalamus
  • thymus
  • pancreas
  • testes and ovaries
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7
Q

Target Cells

A

Cells whose activity is affected by a particular hormone.

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8
Q

How do hormones affect their target cells?

A

Each target cell contains receptor proteins which the hormone can bind to and it triggers other reactions in the target cell.

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9
Q

Exocrine Gland

A
  • release their secretions through ducts or tubes

eg. sweat glands, salivary glands, tear glands

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10
Q

Steroid Hormones

A
  • lipid-based hormones made from cholesterol that can diffuse through the lipid bilayer of cell membranes
  • hydrophobic*
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11
Q

Examples of Steroid Hormones

A

Testosterone, Estrogen, Cortisol

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12
Q

What happens when steroid hormones enter a target cell?

A
  • They bind to receptor proteins which activates specific genes, causing changes in the cell.
  • Hormone/receptor complex acts as a transcription factor turning target genes on or off.
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13
Q

Water-Soluble Hormones

A

-hormones that cannot diffuse across the cell membrane

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14
Q

How does a water-soluble hormone interact with the target cell?

A
  • it will bind to a receptor protein on the surface of the target cell
  • this starts a cascade of reactions inside the target cell which amplifies the impact of a hormone
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15
Q

Examples of Water-Soluble Hormones

A

Epinephrine, Human Growth Hormone (hGH), thyroxine, insulin

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16
Q

Protein Hormones

A

-hydrophilic, large hormone molecules that bind to receptors (transmembrane proteins) on the surface of “target” cells

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17
Q

How does a protein hormone interact with the target cell?

A
  • binding of the hormone to its receptor initiates a sequence of intracellular signals that alter the behaviour of the cell or stimulate gene expression in the nucleus
  • cell begins to produce the appropriate gene products in response to the hormonal signal
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18
Q

Examples of Protein Hormones

A

Insulin, glucagon, oxytocin, antidiuretic hormone

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19
Q

How is hormone production regulated?

A
  • hormone production increases or decreases in response to changing metabolic needs of the body
  • regulated by nervous and endocrine system
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20
Q

The impacts of a specific hormones on the activity of target tissues is a function of what?

A

A) the rate of hormone production and secretion
B) hormone concentration in the blood
C) rate of blood flow to target organ or tissue
D) half life of hormone

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21
Q

Pituitary Gland

A
  • “master gland”
  • controls all other endocrine glands
  • small sac at base of brain connected to hypothalamus
  • produces and stored hormones
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22
Q

Hypothalamus

A

-controls release of hormones by the pituitary gland through the use of hormone releasing and inhibiting hormones

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23
Q

Releasing Hormones

A
  • hormones that stimulate the pituitary gland to secrete hormones that act on other endocrine glands
  • secreted by hypothalamus*
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24
Q

Tropic Hormone

A

-hormone that targets endocrine glands and stimulates them to release other hormones

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25
Q

Process of Hormone Secretion

A

1) Hypothalamus secretes a releasing hormone into anterior pituitary.
2) Anterior pituitary releases a second tropic hormone into bloodstream.
3) Second tropic hormone stimulates target gland to release third hormone into the blood.

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26
Q

How is the process of hormone secretion regulated?

A

Negative Feedback Loop

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27
Q

How does negative feedback in hormones work?

A

-the third hormone secreted prevents further release of the first two hormones in the pathway

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28
Q

How do the functions of the nervous and endocrine systems overlap?

A
  • some nervous system structures, such as cells in the hypothalamus, secrete hormones
  • several chemicals function as both neurotransmitters and hormones
  • both regulated by feedback loops
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29
Q

Functions of the Pituitary Gland

A

-releases six main hormones involved in body’s metabolism, growth, development and other critical life functions

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30
Q

Two Lobes of Pituitary

A

Anterior and Posterior

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31
Q

Posterior Pituitary

A

-stores and releases antidiuretic hormone (ADH) and oxytocin, which are produced in the hypothalamus and transferred to posterior pituitary

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32
Q

Anterior Pituitary

A

-synthesizes and secretes six major hormones

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33
Q

Six Major Hormones Secreted By Anterior Pituitary

A
  • human growth hormone (hGH)
  • prolactin (PRL)
  • thyroid stimulating hormone (TSH)
  • adrenocorticotropic hormone (ACTH)
  • follicle-stimulating hormone (FSH)
  • luteinizing hormone (LH)
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34
Q

Human Growth Hormone (hGH)

A

-hormone that ultimately affects almost every body tissue, by direct stimulation or via tropic effects

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35
Q

What does the hGH do?

A

-stimulates the liver to secrete hormones called growth factors, which along with hGH, influence many physiological process

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36
Q

What physiological processes do hGH and growth factors increase?

A
  • protein synthesis
  • cell division and growth (cartilage, bone, muscle)
  • metabolic breakdown and release of fats stored in adipose (fat) tissue
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37
Q

What parts of the body does hGH stimulate the growth of?

A
  • muscles
  • connective tissue
  • growth plates
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38
Q

What happens when you have too much hGH?

A

Gigantism

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39
Q

What happens when you have too little hGH?

A

Dwarfism

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40
Q

Acromegaly

A

-excessive production of hGH in adulthood which causes bones and soft tissues to widen along with other symptoms

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41
Q

Thyroid Gland

A

-butterfly-shaped gland located below the larynx in the neck

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42
Q

Function of the Thyroid

A

-produces the hormone thyroxine which helps regulate metabolism and growth

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43
Q

Thyroxine (T4)

A

-hormone produced by the thyroid and released into the bloodstream

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44
Q

Function of Thyroxine

A

-increases the rate at which the body metabolizes fat, proteins and carbs for energy

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45
Q

What does thyroxine stimulate?

A

-cells of the heart, skeletal muscles, liver and kidneys to increase cellular respiration

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46
Q

Cretinism

A

-when the thyroid fails to develop properly during childhood

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47
Q

Hypothyroidism

A

-condition resulting when the thyroid produces extremely low levels of thyroxine

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48
Q

Hyperthyroidism

A

-condition resulting when the thyroid produces extremely high levels of thyroxine

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49
Q

Grave’s Disease

A

-severe state of hyperthyroidism that results when immune system attacks thyroid

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50
Q

Negative Feedback Loop of Thyroxine Secretion

A
  • anterior pituitary releases thyroid-stimulating hormone which causes thyroid to secrete thyroxine
  • thyroxine enters blood
  • high levels of thyroxine cause thyroxine itself to feed back to the hypothalamus and anterior pituitary to suppress secretion
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51
Q

Thyroid-Stimulating Hormone

A

-hormone released by the anterior pituitary which causes the thyroid gland to secrete thyroxine

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52
Q

What does the thyroid require for thyroxine production?

A

Iodine

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53
Q

Goitre

A
  • an enlargement of the thyroid gland characterized by a large swelling in the throat
  • associated with a deficiency of iodine
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54
Q

What is calcium essential for?

A
  • healthy teeth and skeletal muscles

- blood clotting, nerve conduction, and muscle contractions

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55
Q

Calcitonin

A

-hormone that regulates levels of calcium in the blood

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56
Q

What happens with excess calcium in blood?

A

-Calcitonin stimulates uptake of calcium into bones

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57
Q

Parathyroid Glands

A

-4 small glands attached to thyroid that produce parathyroid hormone (PTH)

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58
Q

When does the body synthesize and release PTH?

A

-when calcium levels in the blood fall

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59
Q

What does PTH do?

A
  • stimulates bone cells to break down bone material (calcium phosphate) and secrete calcium into the blood
  • stimulates kidneys to reabsorb calcium from the urine activating vitamin D in the process which stimulates the absorption of calcium from food in the intestine
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60
Q

Adrenal Glands

A

-one of a pair of organs located on top of the kidneys which are composed of two layers (each produces different hormones and functions as an independent organ)

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61
Q

Two Layers of the Adrenal Glands

A

Adrenal Medulla (inner) and Adrenal Cortex (outer)

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62
Q

Adrenal Medulla

A
  • the inner layer of the adrenal glands that produces epinephrine and norepinephrine, hormones that regulate the short-tern stress response
  • regulated by nervous system
  • can be removed without an effect
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63
Q

Epinephrine

A

-hormone produced by the adrenal cortex that helps regulate the short-term stress response; also known as adrenaline

64
Q

Short-Term Stress Response

A

-the body’s acute reaction to stress in which the sympathetic nervous system is stimulated

65
Q

How does the adrenal gland respond in response to a stressor?

A
  • neurons of the sympathetic nervous system carry a signal from the hypothalamus directly to the adrenal medulla
  • neurons stimulate the adrenal medulla to secrete epinephrine and small amounts of norepinephrine
66
Q

Body’s Response to Epi and Norepi

A
  • triggers an increase in breathing rate, heart rate, blood pressure, blood flow to the heart and muscles, and the conversion of glycogen to glucose in the liver
  • pupils of the eyes dilate, blood flow to the extremities decreases
67
Q

Why is the release of epi and norepi rapid?

A

Under nervous system control.

68
Q

Adrenal Cortex

A
  • produces glucocorticoids and mineralocorticoids, hormones that regulate the long-tern stress response
  • secretes small amounts of gonadocorticoids (female and male sex hormones)
69
Q

Long-Term Stress Response

A

-sustained psychological response to stressors, characterized by increases in blood glucose and blood pressure and decrease in inflammatory response

70
Q

Glucocorticoids

A

Increase blood sugar level

71
Q

Mineralocorticoids

A

Increase blood pressure

72
Q

Gonadocorticoids

A

Supplement the hormones produced by the gonads.

73
Q

Most Abundant Glucocorticoid

A

Cortisol

74
Q

Cortisol

A
  • released by the adrenal cortex in a long-term stress response
  • triggers an increase in blood glucose levels and reduces inflammation
75
Q

Process of Cortisol Secretion

A
  • brain detects danger
  • hypothalamus secretes releasing hormone
  • releasing hormone stimulates anterior pituitary to secrete adrenocorticotropic hormone (ACTH)
  • ACTH targets adrenal cortex causing release of cortisol
76
Q

Adrenocorticotropic Hormone (ACTH)

A

-hormone synthesized by the anterior pituitary gland to target the adrenal cortex and regulate the production of glucocorticoids

77
Q

Functions of Cortisol

A
  • raises blood glucose levels by breakdown of muscle protein into amino acids
  • breakdown of fat cells to release glucose
78
Q

What do high-levels of cortisol cause?

A
  • impair thinking
  • damage the heart
  • cause high blood pressure
  • lead to diabetes
  • increase susceptibility to infection
  • cause an early death
79
Q

Main Mineralocorticoid

A

Aldosterone

80
Q

Aldosterone

A

-type of mineralocorticoid hormone secreted by the adrenal cortex

81
Q

Function of Aldosterone

A

-stimulates the kidneys to increase the absorption of sodium in the blood which increases the concentration of solutes in the blood, which draws in more water from the kidneys, raising blood pressure

82
Q

Addison’s Disease

A
  • disease caused when adrenal cortex is damaged
  • body secretes inadequate amounts of mineralocorticoids and glucocorticoids
  • symptoms: hypoglycaemia (low blood sugar), sodium and potassium imbalances, rapid weight loss
83
Q

Pancreas

A

-small gland in the abdomen that secretes digestive enzymes and secretes the hormone insulin

84
Q

Islets of Langerhans

A

-clusters of endocrine cells found throughout the pancreas, consisting of glucagon-producing alpha cells and insulin-producing beta cells

85
Q

beta cells

A

-cells of the pancreas that secrete insulin to decrease the level of blood glucose

86
Q

alpha cells

A

-cells of the pancreas that secrete glucagon to increase the level of blood glucose

87
Q

insulin

A

-a hormone secreted by the beta cells in pancreas to make target cells more permeable to glucose

88
Q

glucagon

A

-hormone produces by alpha cells in pancreas to stimulate liver to convert glycogen back into glucose

89
Q

How are insulin and glucagon levels regulated?

A
  • negative feedback
  • high blood glucose, insulin is produced
  • low blood glucose, glucagon is produced
90
Q

Diabetes Mellitus

A
  • a serious chronic condition that results when the pancreas does not make enough insulin or the body does not respond properly to insulin
  • causes hyperglycaemia
91
Q

Hyperglycaemia

A
  • condition resulting from high levels of blood glucose

- occurs in individuals with diabetes mellitus

92
Q

Type 1 Diabetes

A
  • immune system produces antibodies that attack and destroy the beta cells of the pancreas, therefore unable to produce insulin
  • require daily insulin injections in order to live
93
Q

Type 2 Diabetes

A
  • develops gradually, often because the insulin receptors on the body’s cells stop responding to insulin OR beta cells produce less and less insulin over time
  • more common in overweight people
  • can be controlled with diet, exercise and oral medications
  • becoming an epidemic in some parts of the world
94
Q

Gonads

A
  • organ that produces reproductive cells (gametes)

- produces sperm in males and eggs in females

95
Q

Sex Hormone

A

-one of several chemical compounds that control the development and function of the reproductive or secondary sex characteristics

96
Q

Testes

A
  • two male gonads

- held outside of body in scrotum

97
Q

What are the testes composed of?

A
  • long coiled tubes (seminiferous tubules)

- hormone-secreting cells (interstitial cells)

98
Q

Interstitial Cells

A

-secrete testosterone

99
Q

Seminiferous Tubules

A

-where sperm is produced

100
Q

Epididymis

A

-where sperm go from the testes to mature and become motile

101
Q

Ductus Deferens

A

-storage duct that connects to the epididymis which then leads to the penis via the ejaculatory duct

102
Q

Penis

A

-transfers sperm from the male to the female reproductive tract

103
Q

Foreskin

A

-sheath of skin that surrounds and protects the tip called the glans penis

104
Q

Seminal Fluid (semen)

A

-fluid from a series of glands mixed with sperm

105
Q

What happens with semen during sexual arousal?

A

-semen enters urethra from ductus deferentia and it is carried through the penis before it is ejaculated

106
Q

What does the Y chromosome carry?

A

-a gene called the testis-determining factor (TDF) whose action triggers production of male sex hormones

107
Q

Androgens

A

-male sex hormones that initiate the development of male sex organs and ducts in the fetus

108
Q

Puberty

A
  • the period in which the reproductive system completes its development and become fully functional
  • happens due to hormonal events
109
Q

Age of Puberty for Males

A

10-13 Years

110
Q

GONADOTROPIC-RELEASING HORMONE (GnRH)

A

-hormone that acts on the anterior pituitary gland to cause it to release two different sex hormones; luteinizing hormone (LH) and follicle-stimulating hormone (FSH)

111
Q

FOLLICLE-STIMULATING HORMONE (FSH)

A
  • reproductive hormone that stimulates the development of the sex organs and gamete production in males and females
112
Q

LUTEINIZING HORMONE (LH)

A

-reproductive hormone that triggers ovulation, stimulates the formation of the corpus luteum, stimulates estrogen production in the ovaries and testosterone in the testes

113
Q

Testosterone

A

-reproductive hormone that stimulates the development of the male reproductive tract and secondary sex characteristics; only minor effects in females

114
Q

How is sperm production controlled?

A

Hormone Feedback Mechanisms

115
Q

Hormone Feedback Pathway for Sperm Production

A
  • GnRH from the hypothalamus triggers the release of FSH and LH from the anterior pituitary
  • FSH causes the seminiferous tubules to produce sperm
  • at the same time, FSH causes cells in the seminiferous tubules to release inhibin (acts on the anterior pituitary to inhibit production of FSH)
  • as FSH levels drop, testes release less inhibin
116
Q

Inhibin

A

-acts on anterior pituitary to inhibit the production of FSH; produces a negative feedback loop that controls the rate of sperm formation

117
Q

What is the hormonal mechanism for testosterone production?

A

-LH causes the interstitial cells in the testes to release testosterone

118
Q

Andropause

A

-in men, a gradual decline in testosterone level beginning around age 40; symptoms include fatigue, depression, loss of muscle/bone mass, drop in sperm production

119
Q

Female Gonads

A

-ovaries (produce limited number of gametes or ova)

120
Q

Ovaries

A
  • site of oogenesis (ova production)

- two ovaries alternate so that only one produces an egg each month

121
Q

Follicles

A
  • specialized cell structures in the ovary
  • a single ovum develops within each follicle and each month a single follicle matures and then ruptures releasing the ovum into the oviduct (ovulation)
122
Q

Fimbriae

A

-thread-like projections that sweep over the ovary and sweep up an ovum when it is released, moving it to the oviduct

123
Q

Oviduct

A

-carries the ovum from the ovary to the uterus

124
Q

Uterus

A

-muscular organ that holds and nourishes a developing fetus

125
Q

Endometrium

A

-lining of the uterus that is richly supplied with blood vessels to provide nutrients for the fetus

126
Q

Upper and Lower Ends of the Uterus

A
  • upper end connects to oviducts

- lower end forms a narrow opening called the cervix which connects to the vagina

127
Q

Vagina

A
  • entrance for penis to deposit sperm

- exit for fetus

128
Q

Age of Puberty for Females

A

9-13 Years

129
Q

When does a girl begin puberty?

A

-when the hypothalamus increases the production of GnRH which acts on the anterior pituitary to release LH and FSH

130
Q

What do LH and FSH do in females?

A

-act on the ovaries to produce female sex hormones estrogen and progesterone which launch the reproductive cycle

131
Q

Estrogen

A
  • female sex hormone produced in the ovary

- help maintain sexual organs and secondary sexual characteristics

132
Q

Progesterone

A

-female sex hormone produced first by the corpus luteum of the ovary to prepare the uterus for the fertilized egg, and later by the placenta to maintain pregnancy

133
Q

Menstrual Cycle

A
  • in a female, period of 20-45 days during which hormones stimulate the development of the uterine lining, and an egg (ovum) is developed and released from an ovary; if the egg is not fertilized, the uterine lining is shed as the cycle begins again
  • divided into the ovarian and uterine cycle
134
Q

Typical Length of Menstrual Cycle

A

28 Days

135
Q

Location of Ovarian Cycle

A

Ovaries (ironically!)

136
Q

Location of Uterine Cycle

A

Uterus (ironically!)

137
Q

Follicles

A

-structures in the ovary that contain the egg and secrete estrogen

138
Q

How many follicles mature during reproductive years?

A

400

139
Q

What happens in a single ovarian cycle?

A

-one follicle matures, releases an ovum, and then develops into a yellowish, gland like structure known as the corpus luteum which later degenerates

140
Q

First Stage of the Ovarian Cycle

A

Follicular Stage

141
Q

Steps of the Follicular Stage

A
  • increase in FSH released by anterior pituitary which stimulates one follicle to mature
  • as the follicle matures, it releases estrogen and some progesterone
  • increased estrogen in blood acts on anterior pituitary to inhibit FSH release and trigger sudden release of GnRH from hypothalamus
  • leads to increase in LH production triggering ovulation when the follicle bursts releasing the ovum
142
Q

Second Stage of Ovarian Cycle

A

Luteal Stage

143
Q

Steps of the Luteal Stage

A
  • once the ovum is released, LH causes the follicle to develop into a corpus luteum
  • corpus luteum secretes progesterone and some estrogen
  • as hormone levels in blood rise they act on the anterior pituitary to inhibit FSH and LH production
  • corpus luteum degenerates leading to a decrease in levels of estrogen and progesterone
144
Q

What happens if the ovum is fertilized and implants in the endometrium?

A
  • blood hormone levels of est and pro remain high under stimulus of hormones released by embryo-supporting membranes
  • presence of pro maintains endometrium to support fetus
  • presence of est stops ovarian cycle so no additional follicles mature
145
Q

Events of the Uterine Cycle

A
  • build-up of blood vessels and tissues in the endometrium

- if fertilization does not occur, the endometrium disintegrates and menstruation begins

146
Q

When does the uterine cycle begin?

A

-on the first day of menstruation (first day of ovarian cycle)

147
Q

First Five Days of the Uterine Cycle

A

-menstruation occurs and ends with a thin endometrium from being shed

148
Q

Sixth Day of Uterine Cycle

A

-estrogen level is high enough to cause thickening of endometrium

149
Q

After Ovulation and the Uterine Cycle

A

-release of progesterone by corpus luteum causes more rapid thickening of endometrium

150
Q

Day 15 to 23 of the Cycle

A

-thickness of endometrium may double or triple in size

151
Q

Phases of the Menstrual Cycle

A

1) Flow Phase-shedding of the endometrium (Day 1-5)
2) Follicular Stage-development of follicles within ovary with estrogen secretion (Day 6-13)
3) Ovulatory Phase-egg bursts from ovary and follicular cells differentiate into corpus luteum (Day 14)
4) Luteal Phase-characterized by the formation of corpus luteum (Day 15-28)

152
Q

What happens when there is no fertilization?

A
  • decrease in estrogen and progesterone due to degeneration of corpus luteum
  • weak contractions and endometrium is shed
153
Q

What happens when fertilization occurs?

A
  • corpus luteum does not degenerate
  • estrogen and progesterone are sustained
  • no ovulation, endometrium is maintained
154
Q

The Effect of Age on the Menstrual Cycle

A

-number of functioning follicles in female reproductive system decreases with age resulting in gradual decline in the amount of estrogen and progesterone in the blood

155
Q

Menopause

A

-period in a woman’s life during which a decrease in estrogen and progesterone results in an end of menstrual cycles, occurring at age 50

156
Q

Hormone Replacement Therapy

A

-administration of low levels of estrogen and/or progesterone to alleviate symptoms of menopause in females

4U BIO (11 decks)

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