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APHY 104 > Endocrine system > Flashcards

Endocrine system Flashcards

1
Q

Function of the endocrine system and terminology

A

Functions to regulate and coordinate body activities
Terminology
-Tropin- to make something happen or stimulate an effect
The endocrine system is one of 2 control systems of the body – the other is the nervous system.
It is the slower of the two systems

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2
Q

Endocrine glands functions

A

The endocrine system is a general term referring to the group of ductless glands which
Help to maintain homeostasis in the body.
They can also drive change e.g. growth or lactation.
They do this by releasing hormones, these are communication and control molecules
Endocrine glands synthesize, store and then secrete hormones directly into the bloodstream

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3
Q

Hormones are

A

Are chemical messengers that are secreted in response to a stimulus
Have specific receptors at their target organ
The target organ is distant from the endocrine gland
The receptor will respond only to the specific hormone to which it is sensitive
Hormones are controlled by feedback loops that can be negative (usually) or positive

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4
Q

Hormone secretion controlled by

A

Hormone secretion is mainly controlled by negative feedback
Sensors detect when levels of the hormone rise above optimum levels
Signal is sent to stop or decrease production
When the levels drop below optimum, a signal is sent to increase production
Secretion may also be controlled by:
Positive feedback e.g. nursing stimulates prolactin release which stimulates more milk production
Nervous stimulation e.g. the sympathetic NS causes release of adrenalin (epinephrine) during the fight or flight response
Cells that produce locally acting hormones are called paracrine glands
Important in organ and tissue development

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5
Q

Characteristics of they hypothalamus

A

Part of the diencephalon of the brain
Links the cerebrum to the endocrine system i.e conscious to hormones
Regulates appetite, body temperature, and sleep-wake cycles

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6
Q

Pituitary is

A

An endocrine gland attached to the base of the hypothalamus by a thin stalk of nerves and blood vessels- infundibulum
A major control gland of the endocrine system
Has anterior and posterior parts

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7
Q

Relationship b/w hypothalamus and pituitary

A

Blood vessels form a portal system link between the anterior pituitary and the hypothalamus
Hypothalamus receives information from the CNS
Then secretes hormones into its portal system to regulate pituitary hormone secretion
A nervous connection between the posterior pituitary and hypothalamus allows direct transport of oxytocin and antidiuretic (ADH)
Synthesized in the hypothalamus
Stored in the pituitary
Released on stimulation by nerve impulses from the hypothalamus

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8
Q

Characteristics of pituitary gland

A

Controls other endocrine glands
Size of small pea or bean
Attached to hypothalamus by a stalk (infundibulum) and seated in a pocket in the sphenoid bone of the skull
Two parts:
anterior is normal glandular tissue,
posterior is derived from nervous tissue

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9
Q

Anterior pituitary does what

A

Produces 7 known hormones as directed by the hypothalamus and feedback from target organs and tissues
Release of each hormone is controlled by the appropriate releasing hormone from the hypothalamus

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10
Q

Growth hormone is

A

Aka somatotropin or somatotropic hormone
Promotes body growth in young animals, especially bone and muscle.
Protein building
Makes energy available from reserves (stored fat and carbs) → promotes HYPERglycemia

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11
Q

Prolactin is

A

Helps trigger and maintain lactation
Lactation and prolactin secretion continues as long as physical stimulation of nursing or milking continues
Is a positive feedback loop
Animal ‘dries up’ if stimulation stops e.g. weaning

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12
Q

TSh is

A

Thyroid-Stimulating Hormone (TSH or thyrotropin)
Stimulates thyroid gland to produce thyroid hormones
Increased levels if thyroid levels drop
Regulated through the hypothalamus, which will release TSH – releasing hormone to cause TSH to be released from the pituitary
Negative feedback loop regulates

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13
Q

ACTH is

A

Adrenocorticotropic Hormone (ACTH)
Stimulates the cortex of the adrenal gland
Controlled by negative feedback
During stress, the CNS can send signals through the hypothalamus
What does the hypothalamus release?
ACTH- releasing hormone- stimulates pituitary release ACTH
ACTH→ causes release of cortisol and other stress (steroid) hormones from adrenal cortex
CRH= corticotropin releasing hormone. Same as ACTH-RH

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14
Q

FSH is

A

Follicle-Stimulating Hormone (FSH)
In females stimulates growth and development of ovarian follicles
Follicles develop and oocyte (egge) matures
Follicular cells to release estrogen
Promotes the physical and behavioural changes of estrus
In male animals, FSH stimulates growth and development of spermatogenesis- growth and development of sperm
(Estrogen production)

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15
Q

LH is

A

Luteinizing Hormone (LH)
This is the ripening hormone for the follicle (FSH stimulates follicular development)
LH causes the final rupture and release of the egg from the follicle
Males
Called interstitial cell-stimulating hormone (ICSH)
Encourages production of testosterone
FSH and LH are also called gonadotropins because they stimulate growth and development of the glands

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16
Q

MSH is

A

Melanocyte-Stimulating Hormone (MSH)
Uncertain role in most animals at normal levels
Can cause skin to darken at high levels
In reptiles, fish, and amphibians, can cause rapid changes in colour

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17
Q

Posterior pituitary function

A

Does not PRODUCE any hormones
Stores and releases 2 hormones produced by the hypothalamus, as directed by the hypothalamus
Hormones get to the posterior pituitary by transport down the nerve fibers
ADH
Oxytocin

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18
Q

ADH is and function

A

Antidiuretic Hormone (ADH)
AKA= vasopressin
Helps prevent diuresis
Helps conserve water
In kidneys
Increases reabsorption of water from the urine
Urine becomes concentrated, darker, and stronger smelling,
ADH secreted id animals becomes dehydrated and hypothalamus sense hemoconcentration
What is hemoconcentration
Increased RBC concentration
Affects are partially blocked by caffeine and alcohol
What would happen if ADH was absent
PU/PD

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19
Q

Oxytocin is and functions

A

Causes contractions of the uterine muscles at breeding and parturition
At breeding, this helps move sperm up to the oviduct
At parturition, this helps deliver the fetus and placenta
Bonding(behavioural effects) in humans. Used to promote fostering in animals.
Causes milk let down in lactating females. Moves milk from the production and storage part of the mammary gland to the lower part for nursing
Release is stimulated by the sensory stimulation of nursing, intromission, the fetus or sometimes by association (cows)
Often given as a drug to promote delivery of fetus, placenta or milk.

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20
Q

Anatomy of the thyroid gland

A

Two lobes, sometimes connected, on either side and just below larynx
The thyroid glands of several species. The inset cross section shows the ventral connection of the thyroid glands in the pig
Composed of thousands of tiny follicles
Spheres of cells around a central area containing the thyroid hormone precursor (called colloid)

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21
Q

What hormones do they thyroid produce

A

Produces 2 groups of hormones
Thyroid hormone group T3, T4
Calcitonin

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22
Q

Thyroid hormones are

A

Produced in two forms: T3 and T4
Named for how many iodine atoms they have per molecule of hormone.
Produced in response to TSH
T4 is also called thyroxine, main form produced by gland
Usually measured when testing for disease
T3 is the more physiologically active form,
Produced from T4 in tissues

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23
Q

Calorigenic effect of thyroid hormone

A

Helps heat the body by increasing metabolic rate and what production
Production is increased with exposure to cold
Production is decreased by emotional or physical stress (can make animal susceptible to cold or disease)
Effect on Protein, Carbohydrate, and Lipid Metabolism
Increases protein anabolism in the presence of adequate nutrition
Stimulates catabolism during nutritional deficiencies or high thyroid levels
Encourages lipid catabolism
Tends to cause hyperglycemia
Cardiovascular:
Increases heart rate

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24
Q

Effects of thyroid hormone on growth

A

Developmental: Effect on Young, Growing Animals
Necessary for young, growing animals
Helps maturation of CNS and growth and development of muscles and bones

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25
Q

Calcitonin is

A

Produced by C-cells found between the thyroid follicles
Functions to keep blood calcium levels from getting too high
Stimulates storage of excess blood calcium in the bones- this drops blood calcium levels

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26
Q

Parathyroid gland anatomy

A

Variable appearance and location
Generally found on or near thyroid
Often 2 pairs –
one pair on the surface of the thyroid
the other pair within the thyroid
Appear as small pale nodules

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27
Q

Parathyroid hormone is and functions to

A

Aka parathormone
Functions to keep blood calcium levels from getting too low by increasing
Renal retention
Intestinal absorption
Bone calcium mobilization
Also promotes the formation of active form of Vitamin D in the kidneys

28
Q

Adrenal gland anatomy

A

Paired
Found near the cranial end of kidneys
Composed of 2 parts:
Outer layer: adrenal cortex
Inner part: adrenal medulla

29
Q

Adrenal cortex

A

Typical glandular tissue
Makes 3 types of hormones, collectively called steroid hormones
Has 3 layers: producing, from outer to inner layers

30
Q

Mineralcorticoid Hormone is also called and function

A

Aldosterone
Regulates mineral salt (electrolyte) levels
Increases blood sodium, decreases potassium and hydrogen ions through effects on kidneys
Also assists in water retention as water follows reabsorbed sodium

31
Q

Mineralocorticoid Hormone release is stimulated by

A

renin-angiotensin system
Renin is released from the kidneys in response to sympathetic stimulation and decreasing blood pressure
Converts a blood precursor peptide to angiotensin II
Angiotensin II causes vasoconstriction to increase BP and decrease renal perfusion and stimulates aldosterone release to retain fluid

32
Q

Glucocorticoid hormone is

A

Includes cortisone, cortisol, corticosterone
Primarily associated with stress response
Help maintain BP
Mobilizes proteins and fats and promotes gluconeogenesis in the liver
Gluconeogenesis- synthesis of “new” glucose
Have anti-inflammatory effects
Drugs such as prednisone, dexamethasone, triamcinolone, and hydrocortisone mimic the effects of glucocorticoids – often use to control inflammation.

33
Q

Side effects of glucocorticoid hormones producing drugs

A

PU/PD
Immunosuppression
Altered WBC counts
Delayed wound healing
Catabolism of proteins
Abortion
Hyperglycemia
Suppression of normal adrenal cortical secretions
Called iatrogenic hyperadrenocorticism

34
Q

Sex hormones produced by adrenal cortex

A

innermost layer of the Adrenal cortex produces small amounts of androgens and estrogen with minimal systemic effects

35
Q

Adrenal medulla is

A

Nervous tissue origin
Hormone-secreting cells are modified neurons
Produces mainly epinephrine and some norepinephrine
Responds to sympathetic stimulation – ‘fight or flight’ response
Fight or Flight Response

36
Q

Adrenal medulla effects on the body

A

Increased HR
Increased CO
Increased BP
Dilated airways
Decreased GI motility
Increases blood glucose

37
Q

Pancreas shape

A

Long, flat organ that runs alongside the duodenum
Has both exocrine and endocrine functions
Exocrine part secretes digestive enzymes into duodenum
Endocrine part is small, but important!!

38
Q

Pancreatic inlets are and types of hormones produced

A

Thousands of tiny clumps of cells
Scattered throughout the pancreas
Called Islets of Langerhans
Three types of cells in the islets each of which produces its own distinct hormone
Alpha cells= glucagon
Beta cells= insulin
Delta cells= somatostatin

39
Q

Insulin is and does what

A

Vital to life
Allows cells to absorb glucose (works by increasing transport proteins on cell membrane)
Increases glycogen production in liver and muscle
Increases protein and fat synthesis
Primary measured effect is to lower blood glucose

40
Q

Hormones produced by the pancreas

A

Insulin
Glucagon
Somatostatin

41
Q

Hormones produced by the adrenal cortex

A

Mineralcorticoid hormone
Glucocorticoid hormone

42
Q

Glucagon hormone is

A

Not as vital as insulin because other hormones have similar effects in the body
Raises blood glucose
Stimulates glycogenolysis and gluconeogenesis

43
Q

Somatostatin is

A

Inhibits secretion of insulin, glucagon and growth hormone
Decreases GI motility

44
Q

Gonads are

A

The reproductive organs
Paired organs
Testes (singular testis)- males
Ovaries- female
Produce the reproductive cells (spermatozoa and ova) with ½ the number of chromosomes as a human somatic cells
Also produce hormones responsible for development of sex characteristics

45
Q

Testes are and functions

A

Found in the scrotum
Seminiferous tubules continuously produce sperm
Interstitial; cells
Between tubules
Produce androgens
Primarily testosterone
Important for development of male secondary sex characteristics (muscles, libido, accessory sex glands, growth of penis)
Metabolic effect is anabolic
Production stimulated by LH from anterior pituitary

46
Q

Ovaries are

A

Paired organs
Found in the abdomen behind the kidneys
Cyclical production of hormones and ova (eggs)
Controlled by FSH and LH

47
Q

Estrogens are

A

Mainly estradiol and estrone
Produced by developing follicle cells in response to FSH
Cause physical and behavioral changes of estrus – in preparation for breeding and pregnancy
As levels increase, they feedback to pituitary and decrease FSH and increase LH
Ovulation occurs at / just after LH peak (in most animals)

48
Q

Progestins are

A

After ovulation, LH stimulates the empty follicle to develop into a corpus luteum (CL)
CL produces progestins such as progesterone
Very important for maintaining pregnancy

49
Q

Erythropoietin is

A

Produced by the kidneys stimulates RBC production in response to hypoxia
Chronic renal failure is often accompanied by anemia due to decreased EPO production
May become life – threatening and require transfusion or Epo supplementation (very expensive)

50
Q

Placenta is

A

Varies by species, but overall purpose is to help maintain pregnancy
Secretes Estrogen and progesterone
Chorionic gonadotropin: primarily in humans and horses. This is an LH like hormone that maintains the CL. It is used in some pregnancy tests.

51
Q

Thymus is

A

Important in developing immunity in immature animals
Involved in development of T-lymphocytes important for cell-mediated immunity
Hormones include thymosin and thymopoietin
Shrinks to remnant in adulthood

52
Q

Pineal body produces what and affects what

A

Melatonin: affects biological clocks and sleep/wake cycles
High concentration at night
Some people use to for jet lag
Poorly understood – linked to seasonal estrus in some species

53
Q

Excess GH can cause

A

Gigantism
Excess hormone while growing
Exaggerated bone growth, abnormally tall
Acromegaly
Excess hormone when mature
Growth plates are closed, see cartilage proliferation around joints and facial changes- large nose, lips, forehead

54
Q

Deficiency of GH can cause

A

Dwarfism
Alopecia
Thin skin
Secondary abnormalities of thyroid, adrenal and reproductive hormones

55
Q

Diagnosis of diabetes mellitus and treatment

A

Diagnosis: detection of elevated blood glucose and glucose in the urine
Treatment involves the subcutaneous injection of insulin, close monitoring of food intake, blood and urine glucose levels
Canned food for cats!
Special diets can help with the stabilization of insulin dosages

56
Q

Diabetes insipidus is and caused by

A

Caused by a failure of the kidneys to reabsorb water.
Due to either
A deficiency of antidiuretic hormone
Failure of the renal collecting ducts to respond to ADH

57
Q

Clinical signs and diagnosis of diabetes insipidus

A

Clinical signs include
Polyuria
Polydipsia
Very dilute urine (decreased specific gravity)
Diagnosis is made by withholding water and monitoring urine SG, or by administering a synthetic ADH and monitoring urine SG
Water deprivation test- can be dangerous, only withhold water for short time

58
Q

Cushings disease is, clinical signs and diagnosis

A

Caused by excessive administration of steroids (iatrogenic) or by an overproduction of steroids by the adrenal cortex (often due to pituitary or adrenal neoplasia)
Neoplasia = tumor, can be cancerous or non cancerous
Clinical signs include
Polyuria, polydipsia
Increased appetite
Abdominal distension
Muscle atrophy and weakness
Lethargy
Thinning skin and alopecia
Excessively long hair coat in horses
More susceptible to infections
Diagnosis is generally made by blood tests
Base line blood sample, than inject wither
ACTH- adrenocorticotropic hormone
Dexamethasone
Then, take timed blood samples to monitor the cortisol levels

59
Q

Addisons disease is and clinical signs

A

Hypoadrenocorticism
Deficincy of mineralcotocoid +/- glucorticoid from the adrenal cortex, due to
Immune-mediated destruction (most often) long term steroid administaration (iatrogenic) or neoplasia
Low sodium, high potassium, low HR and BP, weakness
Life-threatening!!
Clinical signs include
Polydipsia
Polyuria
Anorexia
Vomiting and diarrhea
Hypotension
Bradycardia
Acute collapse

60
Q

Addisions disease diagnosis and treatment

A

Diagnosis includes blood tests for electrolyte imbalances (especially the sodium and high potassium) and the ACTH stimulation test
Treatment involves the administration of glucocorticoids and mineralocorticoids

61
Q

Goiter thyroid problem is

A

non cancerous thyroid gland enlargement
Usually caused by iodine deficiency
Iodine is a required component of T3 and T4
Body senses decreased T4 levels, so pituitary makes more TSH
Thyroid gland becomes hyperplastic and enlarged, but is still deficient amounts of T3 and T4!!
Hypothyroid
Supplement diet with iodized salt

62
Q

Hypothyroidism is, signs, and treatment

A

Most common in adult dogs
Low levels of T3 and T4
SIgns include alopecia, dry skin, lethargy, weight gain, heat seeking, and slow heart rate
If occurs in young animals, can cause dwarfism- often called cretinism
Stunted growth, abnormal bone formation, mental retardation, sluggishness
Treat with thyroid supplements

63
Q

Hyperthyroidism is, signs and treatment

A

Most common in cats
High levels of T3 and T4
Signs include nervousness, irritability, weight loss despite increased appetite, fast heart rate, vomiting (V+), diarrhea (D+), PU/PD
Treat with surgical removal of gland, medication to inhibit thyroid hormone production (often for life), or radioactive iodine treatment to kill gland

64
Q

Hyperparathyroidism is and clinical signs

A

In secondary hyperparathyroidism blood calcium is low
Renal secondary
Renal diseases stops calcitriol (active vitamin D) formation
Nutritional secondary hyperparathyroidism
Inadequate calcium in diet
Mostly grain or meat
Clinical signs of secondary hyperparathyroidism
Rubber jaw
Lameness
Reluctance to move
Pathological fractures
Limb deformities in growing animals (rickets)
Due to reabsorption of calcium from bone and include (osteoporosis)

65
Q
A

APHY 104 (14 decks)

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