Human Phys Exam 2

What is another name for the fed state that occurs after a meal is consumed?

Absorbtive state

What happens to excess glucose in the body?

It is used for lipogenesis

When the level of the glucose pool falls below normal, which of the following tissues is still able to access glucose from the plasma?

The brain

What are the main molecules used for gluconeogenesis ?

 Amino acids

What is the ultimate fate of proteins in the fasted state?

Deamination of amino acids in the liver 

A student is fasting for religious reasons. Which would you expect?

Increased glycogenolysis and increased lipolysis 

In the fasted state, which hormone combination would occur?

Higher glucagon and lower insulin

How does the binding of insulin to its receptor stimulate glucose uptake from the bloodstream?

 It stimulates insertion of GLUT4 transporters in the cell membrane 

What causes most cases of type 1 diabetes mellitus?

Antibodies and leukocytes destroy pancreatic beta cells. 

Insulin is produced by the __________ cells of the pancreas?

Beta

Differences in Type 1&2 diabetes

1. In( Type 2) diabetes, target cells do not respond normally to insulin.

2. In ( Type 1)diabetes, no insulin is produced.

3. In( Type 1&2)   diabetes, glucose levels remain higher than normal

From which embryonic structure does ovarian tissue develop?

Bipotential gonadal cortex 

The presence or absence of __________ determines whether an embryo will develop into a male or female

(SRY gene)

Which embryonic structure gives rise to the seminal vesicles and vas deferens during fetal differentiation into a male?

Wolffian duct 

Which statement most accurately describes how the sex of a human embryo is determined?

 Embryos with the SRY gene become male; embryos without the gene become female. 

Which hormone released from the hypothalamus regulates gonad function?

Gonadotropin-releasing hormone 

What is unique about GnRH secretion patterns from the hypothalamus?

GnRH is secreted in a pulsatile manner 

Which statement is true about gamete formation?

Human females are thought to be born with all the primary gametes they will ever have.

Which of the following is the site of spermatogenesis in the testis?

Seminiferous tubules 

Testosterone are produced by the __________in testes.

interstitial cells of Leydig 

What is the third phase of the ovarian cycle called, and what occurs during this time?

Luteal phase; transformation of a ruptured follicle into a corpus luteum

Which hormone is the most important regulator of endometrium proliferation during the follicular phase?

Estrogen

What causes the LH surge that occurs during the late follicular phase?

Increasing progesterone and high estrogen levels enhance pituitary responsiveness to GnRH

The first phase of the ovarian cycle is the __________ phase?

 follicular 

Which efferent signaling causes the erection reflex?

Parasympathetic nervous stimulation

To which method of contraception does a contraceptive sponge belong?

Barrier

A male patient is taking a drug that is a parasympathetic antagonist. Which do you predict?

 Decreased erections

What is the role of human chorionic gonadotropin (hCG)?

It causes the corpus luteum to continue to secrete progesterone.

Which of the following is a function of oxytocin?

stimulates uterine contractions during labor

The role of the corpus luteum is to secrete __________.

Progesterone/ estrogen

In what scenario increases insulin?

A. Giving a bolus of glucose via IV 

B. by consuming a high glucose drink

B. insulin triggered by parasympathetic nervous system due to ingesting and digesting the glucose

How do you find the day of ovulation from a cycle?

Subtract 14 days from the last day of the cycle to find ovulation. 

memorize this whole chart it will be on the exam free response

What does normal growth depend on?

1. Growth hormone and other hormones

2. An adequate diet

3. Absence of chronic stress

4. Genetics

Growth Hormone

growth hormone is released form the Anterior Pituitary gland. It is stimulated by the release of GHRH and inhibited by somatostatin both from the hypothalamus. Growth hormone (peptide) causes the Liver to release insulin like growth factors causing cartilage growth, increased blood glucose, bone/tissue growth.

Does growth hormone only inflfuence the liver?

No, growth hormone also acts on other body tissues as well as the liver.

What are the stimulatory factors from Growth hormone release?

• Stage III and IV sleep

• Stress

• Exercise

• Hormones of puberty

• Fasting or starvation

• Decreased fatty acid concentration

• Decreased glucose concentration

What are the inhibitory factors of growth hormone release?

• Obesity

• Senescence

• Somatostatin

• Growth hormone

• Increased IGF

• Increased [glucose]

• Increased [fatty acid

What stimulates secretion of insulin-like growth factors?

when growth hormone binds growth hormone-binding protein (GHBP) in the blood.

What are the actions of growth hormone?

1. GH and IGF – stimulate protein synthesis

2. GH–increases lipolysis and gluconeogenesis, decreases glucose uptake by muscle → increases blood glucose

3. GH and IGF – increase bone growth

What are the impacts of over secretion and under secretion of growth hormone?

– Severe GH deficiency in childhood leads to dwarfism

– Oversecretion of GH in children leads to gigantism

– Adults with excessive secretion of GH develop acromegaly

Which of the following statements about growth hormone is incorrect?

a. Cortisol released in response to stress inhibits the release of GH.

b. Hypersecretion of GH in children causes gigantism.

c. Hyposecretion of GH in children can be treated with bovine GH.

d. Hypersecretion of GH in adults causes acromelaly.

C, is incorrect

What does tissue growth require?

• GH, and IGFs are required for protein synthesis and cell division

• Thyroid hormones (T3,T4),

• Insulin-stimulates protein synthesis and provides energy (glucose

How does bone remodeling occur?

Total body calcium = intake − output

1. Total body Ca is all the calcium in the body distributed among three Compartments

• Extracellular fluid - Neurotransmitter release at synapse • Role in myocardial and smooth muscle contraction • Cofactor in coagulation cascade • “Cement” for tight junctions • Influences excitability of neurons

• Intracellular Ca 2+ -Muscle contraction ,Signal in second messenger pathways

• Extracellular matrix (bone) -Calcified matrix of bone and teeth

2. Intake is the Ca 2+ ingested in the diet and absorbed in the small intestines, regulated by hormones

3. Output, or Ca 2+ loss from the body, occurs primarily through the kidneys

• Small amount excreted in feces

What are the hormones tht control calicum balance?

1.Parathyroid Hormone

2. Calcitriol

3. Calcitonin

Parathyroid hormone

Is released from the parathyroid glands

– Stimulus for release is a decrease in plasma ionized Ca2+ concentration. Monitored by Ca2+

- sensing receptor (CaSR)– Raises Ca2+ in three ways

• . PTH mobilizes calcium from bone

• PTH enhances renal reabsorption of calcium

• . PTH indirectly increases intestinal absorption of

Calcitriol

– Also called 1, 25-dihydroxycholecalciferol, or vitamin D3

– Primary hormone responsible for enhancing 2+ Ca

– Facilitates renal reabsorption of

– Helps mobilize 2+ Ca Ca 2+ out of bone

– Production is regulated by the action of PTH

Calcitonin

– Produced by C cells of the thyroid gland

– Released when plasma 2+ Ca increases

– Decreases bone resorption– Increases renal calcium excretion

– Used to treat Paget’s disease

hypocalcemia (low calium)

can cause muscle cramps, convulsions/seizures, numbness/tingling, hyperactive bowel, brittle hair/nails

hypercalcemia (high calcium)

muscle weakness, constipation, hypertension, polydipsia, polyurea, lethargy/coma

what is osteoporosis?

• Metabolic disorder in which bone resorption exceeds bone deposition

– Most common in women after menopause

– Risk factors include ▪ Postmenopausal age ▪ Smoking ▪ Low dietary 2+ Ca intake

• Prevent or slow down loss of Ca 2+ from bones by

– Maintain adequate dietary 2+ intake

– Perform weight-bearing exercise

Increased levels of phosphate ions in the body would likely accompany ___________.

a. Bone loss during osteoporosis

b. Elevated activity of osteoblasts

c. High levels of growth hormone

d. Calcitonin release.

A. Bone loss during osteoporosis

Concerning calcium homeostasis, which relationship is correctly stated?

a. Once incorporated into the hydroxyapatite of the bones, calcium cannot be released. b. Parathormone triggers increased activity in osteoblasts.

c. Absorption of dietary calcium by the small intestine in not hormonally regulated.

d. Osteoblasts build bone, and osteoblasts catalyze its reabsorption.

b. Parathormone triggers increased activity in osteoblasts

fed-state (Absorptive state) metabolism

• Carbohydrates make ATP

– Glucose storage

▪ Glycogen for short-term storage and fat for long-term storage

• Amino acids make proteins

– Structural and functional proteins, enzymes, hormones, amine hormones, neurotransmitters

– Excess amino acids are burned as energy or stored as fat

Fasted state metabolism

• glycogenolysis occurs- glycogen converts to glucose

• Proteins used to make ATP- through deamination of amino acids and ammonia used to make urea

• Lipids store more energy than glucose or protein

– Lipids broken down through lipolysis

– Glycerol feeds into glycolysis

– Fatty acids undergo beta-oxidation beta-oxid ation to produce acetyl CoA

– Excess acetyl CoA becomes ketone bodies (ketones or keto acids)

▪ Strong metabolic acids lead to ketoacidosis

Fasted state metabolism diagram

what is glycogenolysis?

breaking down glycogen into glucose-1-phosphate, whihc is then converted to glucose-6-phosphate providing energy (extra ATP) and maintaining blood glucose levels during fasting

amino acid catabolism

Deamination: removal of the amino group from an amino acid creates ammonia and an organic acid during glycolysis/ citric acid cycle. The ammonia is then converted to urea.

Gluconeogenesis

Process where pyruvate, amino acids, lactate, and glycerol are converted to glucose 6-phosphate and is converted to glucose in the liver and kidney.

lipolysis

when triglycerides are metabolized for the production of ATP.

STEPS:

• Lipases digest triglycerides into glycerol/ 3 fatty acids.

• Glycerol becomes a glycolysis substrate.

• Beta-oxidation chops 2-carbon acyl units off the fatty acids.

• Acyl units become actyl CoA and can be used in the citric acid cycle

During the absorptive state in a person at rest,

a. the liver forms glycogen.

b. adipocytes release fatty acids into plasma.

c. skeletal muscles increase glycogen breakdown.

d. gluconeogenesis increases.

a. The liver forms glycogen

Which is TRUE about fasted-state metabolism?

a. it is catabolic

b. maintains plasma glucose for the brain

c. leads to the formation of ketone bodies

d. promotes gluconeogenesis

e. All of the above

e. All of the above

What secretes insulin and glucagon?

The pancreas

Islets of Langerhans

Beta cells- secrete insulin

Alpha cells- secrete glucagon

D cells- secrete somatostain (inhibits GH)

PPcells- (F cells) secrete pancreatic polypeptide

How does the insulin to glucagon ratio regulate metabolism?

– In the fed state, insulin dominates to lower blood glucose

– In the fasting state, glucagon dominates to increase blood glucose

insulin

• formed in the pancreas from beta cells

• is released in the fed state to lower blood glucose

• 5 min half life and dissolved in plasma

• Targets: Liver, muscle, adipose tissue

• increases glucose oxidation, synthesis

• increase fat synthesis

• increases protein synthesis

what shuts off insulin release?

a decrease in plasma glucose shuts down the release of insulin via negative feedback

• GH and cortisol are antagonistic to insulin

what stimulates insulin secretion?

1. Increased plasma glucose

2. Increased plasma amino acids

3. Feedforward effects of GI hormones

4. Parasympathetic activity causing beta cells to release insulin

what Inhibit insulin secretion?

Sympathetic activity

Glucagon

• formed in the pancreas from Alpha cells

• is released in the fasting state to raise blood glucose

• Increases glycogenolysis

• increases gluconeogenesis

• increases ketogenesis

• Target cell: Liver

• Target receptor: G-protien coupled receptor linked to cAMP

• increased plasma glucose decreases glucagon secretion

• prventts hypoglycemia

adrenal catecholamines: Epinephrine and Norepinephrine-

released from the adrenal medulla.

• amines made from tyrosine

• 2 min half life and peptide hormones

• Released during fight/ fllight response via CNS and autonomic NS.

• Target cells: Heart, neurons, pancreatic endocrine cells

• Target receptors: G-protien coupled receptors: a/ B subtypes

• Second messenger: cAMP for a2/ b receptors, IP3 for a1 receptors

• causes increase in blood glucose and decreases insulin secretion

How does insulin promote anabolism?

• Insulin binds to tyrosine kinase receptor

– Activates insulin-receptor substrates (IRS)

• Insulin lowers plasma glucose

1. Insulin increases glucose transport into most, but not all, insulin-sensitive cells

2. Insulin enhances utilization and uptake of glucose

3. Insulin enhances utilization of amino acids

4. Insulin promotes lipogenesis: fat synthesis.

what does insulin promote in adipose tissue

promotes glucose uptake, lipogensis

decreases lipolysis

what does insulin promote in striated muscle

promotes glucose uptake, glycogen synthesis, and protein synthesis

what does insulin promote in the liver?

promotes glycogen synthesis, and lipogenesis

decreases gluconeogenesis

what is the cellular mechanism of action for insulin?

• insulin binds to tyrosine kinase receptor

• receptor phosphorylates insulin-receptor substrates (IRS)

• second messenger pathways (GLUT 4 turns glucose into glucose6 phosphate with hexokinase II alter protein synthesis and existing proteins

• membrane transport is modified

• resulting in changes in metabolism

Are there GLUT 4 transporters on the membrane during the fasted state?

No, due to the absence of insulin there are no GLUT 4 transporters in the membrane to take up glucose

GLUT 4 only present on the membrane during the release of insulin to allow uptake of glucose into adipose/ skeletal muscle cells

What happens to glucose transport in the fasted/ fed state with liver hepatocytes?

• Fasted state- hepatocytes makes glucose and transports it out into the blood using GLUT 2 transporters to increase blood glucose

• Fed State- the glucose concentration reverses and glucose enters the hepatocyte to lower blood glucose

what is glucagon release stimulated by?

– low blood glucose

– plasma amino acids

How does glucagon prevent hypoglycemia?

– Liver is primary target\

– Stimulates glycogenolysis and gluconeogenesis

Diabetes mellitus (DM)

DM- abnormally elevated plasma glucose concentrations or hyperglycemia

Type 1 diabetes mellitus—insulin deficiency from autoimmune destruction of beta cells

• high glucose levels with little to no insulin

Type 2 diabetes mellitus—insulin-resistant diabetes

• cells desensitized to glucose resulting in lack of insulin produced

Type 1 diabetes mellitus

genetic predisposition sometimes preceded by viral infection often in childhood • Without insulin cells go into fasted-state metabolism

—insulin deficiency from autoimmune destruction of beta cells

• high glucose levels with little to no insulin

1. Protein metabolism

2. Fat metabolism

3. Glucose metabolism—hyperglycemia

4. Brain metabolism—excessive eating (polyphagia)

5. Osmotic diuresis and polyuria—glucose in urine (glucouria) and excessive urination (polyuria)

6. Dehydration—thirst and excessive drinking polydipsia

7. Metabolic acidosis

What accounts for 90% of diabetes cases?

Type II diabetes, caused by excessive insulin release resulting in beta cells resistance to insulin.

First therapy: exercise and weight loss •

Drugs

1. stimulate beta-cell secretion of insulin

2. slow the digestion or absorption of carbohydrates

3. inhibit hepatic glucose output

4. make target tissues more responsive to insulin

5. promote glucose excretion in urine

6. mimic endogenous hormones—amylin, incretin mimetics

Which is NOT true about type 2 diabetes mellitus?

a. 90% of all diabetes mellitus

b. caused by beta cell destruction

c. related to poor lifestyle habits

d. cells are insulin-resistant

e. plasma insulin levels are often elevated

b. caused by beta cell destruction

Patients with diabetes inject insulin rather than taking it as a pill because

a. injected insulin quickly enters the blood

b. injecting helps it cross the blood-brain barrier.

c. injected insulin reaches most cells before passing through the liver

d. oral insulin is broken down in the digestive tract.

d. oral insulin is broken down in the digestive tract.

what are the three sex organ structures?

1. Gonads

2. Internal genitalia

3. External genitalia

Gonads

contain germ cells and produce gametes and sex hormones

▪ Male gonads are testes– Produce sperm

▪ Female gonads are ovaries– Produce ova

Internal genitalia

Accessory glands and ducts

External genitalia

External reproductive structures

Sex Chromosomes

humans (23p) 46 chromosomes, 22p autosomes and 1p sex chromosomes

– XX = female

– XY = male

▪ SRY segment is essential for development of the male reproductive organs

– Sperm determines sex of zygote!!!!

Bipotential gonads

– Testes develop at 6-7 weeks gestation in genetic males

– Ovaries develop at 9 weeks gestation in genetic females

Internal phenotypic sex characteristics male vs female

Male: wolffian ducts

Female: Müllerian ducts

external phenotypic sex characteristsics

genital tubercle, urethral folds, urethral groove, and labioscrotal swelling

human embryonic sexual development

Human embryonic sexual development cont.

Male embryonic development

Male Embryonic Development (with SRY gene on Y chromosome)

– Wolffian ducts develop into epididymis, vas deferens, and seminal vesicle (with testosterone)

– Testes develop later testosterone not required) then descend in the scrotum (with testosterone)

▪ Sertoli cells secrete anti-Müllerian hormone (AMH)

▪ Interstitial (Leydig) cells secrete androgens: testosterone and dihydrotestosterone

• (DHT)– 5-alpha-reductase

what causes progesterone to become corticosterone and cortisol?

21B−hydroxylase